Moderate Speed... Any Weather [Archive]

tri - star

03-22-2007, 07:36 AM

Having designed/built vessels that:
" ....travel {with much less} concern for weather."

A few thoughts:

The short answer(s):
( A.) Maybe......
( B.) Only with difficulty....
( C.) Probably.

As:
- Semi - planing occurs right in the speed zone you are thinking of.
- Where fuel costs and the power needed, can easily be double
- of what is required at displ.....or planing speed.
This is especially true of:
Narrow, heavy, deep " Veed " boats.
Whereas, a lighter vessel - with a flatter " V " - will hop onto plane,
with little fuss and bother. But might have difficuty, in heavy seas.

What you are looking for; has been studiously debated for the last
100 yrs or so. - And it continues......

That's why they pay us designers, the big bucks.
Yeah... If only.......

You sound like a " belt and braces " kind of a guy.
So I doubt that the "radical" designs I favour - will interest you.

Planing vessels have only been around since light weight, powerfull
engines became available. So the engineering of said, planing vessels,
is still undergoing change and developement.

Whereas, displ. boats go back thousands of years....With many well
proven designs out there.

It's your choice.

'Regards.

ALowell

03-22-2007, 07:56 AM

Actually I'm quite open to exotic designs. I have researched extensively foils, surface effect, and catamaran designs, but other than computer controlled foils, none of them seem to be capable of rough weather at the size I'm looking for. Also, ease of building is paramount because I intend to build this myself. This means all but the most basic hull shapes (not to mention foils) are ruled out.

Of course speed vs. seakeeping has alway been the biggest compromise in most designs, but I was hoping that moderate speed would allow me to avoid the usual "I want to go 100 knots and have a marble jacuzzi" problem. Perhaps lowering my speed requirement and flattening the hull is the answer?

Has anyone heard of Port Erie Catamarans? The owner makes some improbable claims regarding ride that, if true, would be quite amazing.

http://www.porterieboats.com/

~ ALowell

safewalrus

03-22-2007, 09:10 AM

Depends on two things your idea on moderate speed and what do you consider poor weather! Get it wrong with a 23 foot boat in 'real' weather and you'll be airborne rather than planing! Shortly after yo ustand a good chance of being in that comotose state that is sometimes known as 'dead' - don't get me wrong I wouldn't want to put you off doing anything; but the comment "travel whaterever the weather" and the mention of 20 knots and 23 feet together fill me with dread! Nor so much for you - if you wish to kill yourself thats your concern, I'm more concerned for the poor devils in your local rescue service who will have to come out to rescue you!! Once it's all gone to rats***

Raggi_Thor

03-22-2007, 09:13 AM

Always optimistic :-)

ALowell

03-22-2007, 09:28 AM

I guess when I say no regard for weather what I mean is traveling in wind up to 15-20 mph. Obviously I'm not going out in a gale or hurricane. Just like when you drive a car -- you don't drive in a blizzard, but you do drive in rain, snow, etc.

Basically I don't want to have to wake up at 5 am to travel before the wind comes up -- I'm not some sort of daredevil.

~ ALowell

ALowell

03-22-2007, 10:19 AM

The short answer(s):
( A.) Maybe......
( B.) Only with difficulty....
( C.) Probably.

Tri - star:

Can you expand? Why not use constant vee for a 20 mph boat? Is it only used for boats that are at risk of leaving and re-entering the water?

Also, is there a method for predicting hp requirement based on weight and vee angle?

Thanks,

~ ALowell

Crag Cay

03-22-2007, 10:30 AM

Don't worry unduly about those sorts of comments. If they do come out to help you they will probably come out in a deep V open boat designed to run in any weather at about 20kts. You could then compare notes!

However, although the hull is slim, the tubes give them the beam to resist transfers upset even though they are hardly immersed at rest. They also have inflatable righting air bags on the arch (available from Henshaws) and immersion proof engines (available second hand from Barrus) to make them truly 'all weather'. Oh, they also cost 150000 USD.

One of these shows what it must look like to have one heave into view at the right moment, although in this case was taken from the stern of a larger AWLB.
http://www.boatdesign.net/forums/attachment.php?attachmentid=12148&stc=1&d=1174573639
http://www.boatdesign.net/forums/attachment.php?attachmentid=12149&stc=1&d=1174573639

tri - star

03-22-2007, 11:18 AM

To ALowell:
You have never been on one of my boats.

If you had, you would have less doubts - about certain, relatively
simple hull forms. That do indeed perform well:
- In rough conditions.

Armchair theorists are always bringing up foils.
A technology invented and proven to work in Canada - almost a
hundred years ago now. Obviously, there are also, some thing(s)
working against using them. In the every day world.
- Or else, why are they not every where you look ?
- After all this time?
If you have a few hours to spend, I can tell you why. Even with
computer assist - there are issues that remain.
That will not go away. You will pay for dinner.

People who have been on a " surface effect ship " know how
effective they can be. Although, with so little of the vessel,
displacing any water at all....it may be questioned if an SES,
can really be defined as a boat anymore !
Also, at present they dont come cheap - or simple.

Cats and Tri - hulls are more commonplace.
However; ever since 20 knot, " native " boats welcomed Capt. Cook's
5 knot ship to the Islands - vested interests have been in denial as
to the viability of these " primitive " vessels.
Particularly, in places like England and where you live.
In the North Eastern US.

Thankfully; there is a sea change coming.
Both the US and British Navies have spent and will continue to
spend Billions of Euros / Dollars to answer your very question !
(Amazing how big a response one can get - by starting a Thread on
Boat Design Forums.)
Narrow, deep " Vees " - Semi-planing ships - Cats and Tri - hulls:
- Have all been tested and orders are in place. For all of the above.
( Except perhaps, note: For foil supported ships.)
I say thankfully, as soon, I will feel less alone in the wilderness,
calling into the wind.
As after sea trials, of all the ships above. This debate of several
hundred years: will finaly simmer down.
- Then I will be able to get some rest and will not be required to as evangelical in the future.

Cheers !

ALowell

03-22-2007, 11:23 AM

tri - star:

You don't have to tell me not to use foils. If you remember, I already mentioned that home building rules them out.

Crag Cay:

I've seen lots of pictures of RIBs where the tubes are well clear of the water at rest. What are they there for if not to stabilize the boat at rest? Do they prevent tips in quartering/beam seas?

It seems to me a RIB might actually ride better with the collar removed - this would have the same effect as removing chine flats and therefore lift. Obviously this would make them unsafe, but I guess I want to build a collarless RIB by counteracting the instability with greater freeboard and ballast.

But my main question is still unanswered: Does anyone have experience running deep vee hulls at moderate to low speeds? What is the minimum planing speed for a 26 degree hull?

tri - star

03-22-2007, 12:14 PM

To ALowell:

Re:
( A.) - "...why not...constant " V "....".
( B.) - "...hp...based on weight and V angle ?"

( A.)
I choose my words very carefully in these matters.
Note: I said " Maybe..."
As it depends.... On various factors.
We were involved in the design of a 65 ft vessel that was
constant in it's V, forward, to mid ships. However, not for all
the reasons that you might presume.
i.e.
If jet drives are a possibility. Then a constant V, well forward:
- Is a requirement. Not really an option.
As you do not want any confused flow ahead of the intake.

Also, if you are happy to stay under 20 knots - and prop(s)
are intended - there are a many ways to reduce the " hump "
getting on plane. That are now open to us.
They might not includ the simplisity of a constant V.

( B.)
FRANCI OTTO is very generous and precise with mathmatical
formulas.
In fact I think he posted something very close to your question,
just a few days ago.
If you check all his posts you will find answers - to most of your
concerns - and beyond.

Cheers !

ALowell

03-22-2007, 12:31 PM

tri - star:

Also, if you are happy to stay under 20 knots - and prop(s)
are intended - there are a many ways to reduce the " hump "
getting on plane. That are now open to us.
They might not includ the simplisity of a constant V.

I intend to use outboard power, so this would apply to me. What are you suggesting to reduce hump? Flatter aft sections?

Thanks for the info.

~ ALowell

tri - star

03-22-2007, 01:00 PM

"...experience running deep vee...."
Yes, I do.

It is just is not practical.
There is a lot of reasons - why not too.
It's absolutely the worst speed range for a deep V.
The vessel's bow will be hard to see over much of the time.
The steering will be sloppy.
It will hunt back and forth.
Want to lean over this way and that - both from waves
on the beam and cross winds.
In bad weather, it will be going on and off plane all the time.

A deep V shines at high speeds. But they do not like to trundle
along - hovering close to dipls. speed.
All the time devouring prodigous amounts of fuel.

".....min....planing speed for...26 degree hull."
A lot depends on how much beer you bring on board. I'm serious.
And where you stow it !
You are looking for a simplistic answer for a very complex problem.
Once again - I refer you to OTTO.

It is ABSOLUTELY a myth that the V angle is the only
determinant - on the onset of planing. The C. of G. can have
as much effect. Or more. So there is no easy answer to your
concern.

Time for you to build some decent sized models and find out
for your self.

That's all folk's.... turning off the computer. Have to see a
man about a boat.

Cheers !

safewalrus

03-22-2007, 05:38 PM

One thing Crag they won't be sending the RNLI they don't operate further than some thirty miles from the UK! (especially in ILB's)

And taking the 'collar' off a Ridgid Inflatable Boat means it ain't Inflatable anymore!

Yep Raggi, that's me every optomistic, but he ain't going out in really rough weather - I wouldn't even call it rough weather! Bit of lop is all, do't get interesting until it's close to 30 Knots! but you got to establish what he's going into and his knowledge (there again I think that's been done by the fact that he's posting.......so my original warning rests!)

ALowell

03-22-2007, 06:19 PM

Yep Raggi, that's me every optomistic, but he ain't going out in really rough weather - I wouldn't even call it rough weather! Bit of lop is all, do't get interesting until it's close to 30 Knots! but you got to establish what he's going into and his knowledge (there again I think that's been done by the fact that he's posting.......so my original warning rests!)

If you don't mind, you can address your statements to me, instead of referring to me in the third person (it's rude).

As to knowledge, let me say that I am a USCG licensed captain, 100 Tons. As to weather, I think most people tend to seriously overestimate wind speeds - 20 knots is a lot of wind, especially when you consider the shoals and currents I encounter on a daily basis. Anyone familiar with Woods Hole knows how treacherous it can be even with no wind at all.

Furthermore, let me say that I am frustrated with the widespread assumption that I know nothing about boats. A RIB without it's collar isn't inflatable? Oh gosh - I hadn't realized that! Explaining to me that vee angle is not the only determinate of speed is telling me something I already know. When I ask about it, I am assuming other variables (weight, CG, CB, etc.) are within average limits. I know a deep vee hull is crappy at hull speed, why else do you think I would be asking about minimum planing speed? And I know that variable deadrise will fix the problem, that's why I started the thread - to find out if people knew about alternatives.

Sorry if I'm sounding a bit huffy - I guess I should have made myself clearer from the start.

Thanks anyway,

~ ALowell

RonW

03-22-2007, 09:32 PM

Hey ALowell - Your question I find interesting, enough so that after reading off and on this forum, I decided to join just to respond to your question.

I think to find the design you are looking for, you need to reach back in time to the early and mid 1900's when the semi-dissplacement hulls where being designed. Now everything is planning hulls. The common launch of a by gone era. Check out these 2 boats, the piute by weston farmer and the able mable by bill atkin. Both of these are 25 footers, but I think are close to what you are looking for. And both of these hull designs come from the 1950's.

http://www.duckworksmagazine.com/05/designs/farmer/piute/free.htm

http://www.boat-links.com/Atkinco/Utilities/AbleMabel.html

I believe that both of these will reasonably handle rough water in the mid teens as cruising. And I believe that both designs can be altered to a outboard by way of using a manual jackplate to the back of the transom.
There are others by bill atkin as well on the same site.

Raggi_Thor

03-23-2007, 04:19 AM

ALowell,
Don't let the walrus annoy you, I think he has a warm hart under the rough surface :-)

It's hard to know how much you know already.
I think what you ask about is a compromise (as always) between weight, waterline area and power (economy). Heavier boats with deeper hull have better motions in a seaway, but need more power (fuel). Deep Vs often have lifting strakes, maybe e very narrow flat bottom, a kind of cut off V, is just as good.

charmc

03-23-2007, 04:50 AM

Has anyone heard of Port Erie Catamarans? The owner makes some improbable claims regarding ride that, if true, would be quite amazing.

http://www.porterieboats.com/

~ ALowell

Here is more: http://www.porterieboats.com/story.htm

Ken Handman, the designer, has a number of successes to his credit.

Good luck,

Charlie

ALowell

03-23-2007, 05:07 PM

I think what you ask about is a compromise (as always) between weight, waterline area and power (economy). Heavier boats with deeper hull have better motions in a seaway, but need more power (fuel). Deep Vs often have lifting strakes, maybe e very narrow flat bottom, a kind of cut off V, is just as good.

I guess I had hoped mine was a new spin on the usual compromise: by going slower (20 mph) I was hoping to mitigate some of the fuel costs associated with heavy deep vees. Thus my interest in planing characteristics at this speed, especially with narrow Serter type hullforms.

Maybe I'll get lucky and get a ride on some magnificent DARPA prototype. Anyone know of a way to talk my way aboard?:)

~ ALowell

P.S. safewalrus deserves my apologies if I offended him - it's easy to get frustrated with board-type communiques.

PAR

03-24-2007, 03:09 AM

The sea state will dictate the speed that any vessel can safely "disregard the conditions". This is basic seamanship, you run what the conditions will permit. Each hull design will have a different sweet spot, that will not tax the skipper, crew, the structure or the whirling bits of machinery lurking in the bilge or hanging off the stern. If you have a specific location or locations that you will be mostly operating your craft, then it's very likely a shape has been developed to address the particularities of that region. This is one of the skills of the designer, assembling vessel lines to accommodate the waters the craft may ply. There is no rule or guide that can be referred to, in the sense that a hull of such and such, with such and such will tolerate such and such.

If you are intent on designing a boat yourself, then you've got some study to absorb. The different elements can be numerous, but it can be done in a reasonable amount of time. If time is your limitation, then you'll likely have to use someone else's research or possible a complete design, that has addressed the needs you desire in this craft.

Hull shapes all have their advantages and disadvantages. I'm in agreement with the dislike of a deeper "V" section for your low speed plane efforts in a rough slosh. This form just isn't in it's element at these speeds. A have no issues with your desire for a constant deadrise craft, but the angle should be reconsidered, to suit the conditions and performance envelope you expect to encounter most often.

I would strongly recommend you closely pattern your craft after successful vessels of the area, unless you feel confidant enough about your abilities, in developing a better suited hull form. There are many variables to reconcile in the design process and the information necessary can be intimating to some.

I'd also like to add, we should consider that ALowell is a relatively new poster and doesn't necessarily need to be bashed about. It's often difficult to judge a "voice inflection" of a specific post, awkward comment or sentence structure, especially one that doesn't provide an obvious escape route. These things can lead to misunderstood intentions or interpretations of remarks. This is a Design thread, not the open forum, which often becomes a bilge at times, unfortunately. Play nice folks . . .

ALowell

03-24-2007, 10:36 AM

I would strongly recommend you closely pattern your craft after successful vessels of the area, unless you feel confidant enough about your abilities, in developing a better suited hull form. There are many variables to reconcile in the design process and the information necessary can be intimating to some.

I think this is valid advice, unfortunately local craft are mostly 50-60 foot hull-speed steel trawlers. Beyond these, vessels here are the same production boats as most anywhere else. Regulators are particularly popular, but their fuel consumption and power requirements are things I wanted to improve on.

I think I've been convinced not to pursue a deep vee. Now I'm considering a catamaran. How much better can the ride be made by moving the bridge-deck back 1/3 or 1/2 of the hull length? Does this just delay the inevitable slamming, or does it help?

Thanks,

~ ALowell

RonW

03-24-2007, 01:26 PM

I find the disscussion on boats that ride and handle choppy water interesting, but unfortunately usually dissapointing and limited. It seems to always go back to try and figure out a better design on a planning hull, trying to force the design to do something that it is just not capable of doing. Which is creating a smooth ride in choppy and rough water. Unfortunately when a planning hull is doing what it is designed to do, which is to come up out of the water and skim over it, with some or most of the hull above the water, that leaves the bottom totally exposed to being slammed by waves and chop.
The inevitable slamming that alowell mentions above.
There just isn't a way around this, unless of course you put the boat on foils and get it to ride high enough above the chop so as to not be banged back and forth. A little overkill and exspense.
Then the conversation leads back to the full dissplacement, but at 8 m.p.h. most are dissatisfied with the speed, kinda going no where not very fast.
The desired speed range seems to almost always be 20 to 25 m.p.h. which at least for a boat in the mid 20 ft. range dictates a planning hull.
If the speed range was dropped by only by 5 m.p.h. to 15 to 20 m.p.h. then the conversation should lead into the semi-dissplacement hull that was designed for these speeds and it stays in the water cutting the waves rather then on top of it and slamming through one chop after another one.
I think it is unfortunate that these hull designs have been almost forgotten and take a very hard back seat to the faster more modern planning hull that rides smooth on clean water, and does little less well, even sitting at the dock bobing back and forth from waves and chop.

It seems though that the semi- hull is being revised though.
Besides the 2, I posted above there are smaller versions as well, such as the handy billy, atkin's ninigret and bateau has a spin off of the ninigret as the nina, all semi-hulls that ride smoothly and stay in the water and can run close to 20 m.p.h. but are not full planning hulls.
I would think anyone that would want a rough water boat would consider and examine these type of hulls.

http://www.southportislandmarine.com/southporthb.htm

http://www.bateau.com/studyplans/LB22_study.htm

http://www.boat-links.com/Atkinco/Oar/Ninigret.html

ALowell

03-24-2007, 02:41 PM

It seems though that the semi- hull is being revised though. Besides the 2, I posted above there are smaller versions as well, such as the handy billy, atkin's ninigret and bateau has a spin off of the ninigret as the nina, all semi-hulls that ride smoothly and stay in the water and can run close to 20 m.p.h. but are not full planning hulls.
I would think anyone that would want a rough water boat would consider and examine these type of hulls.

I have ridden extensively in a Handy Billy and I was exasperated by its unseaworthiness. It "chine walks", cannot be used for work because of the inaccessibility to the transom, and it is scary in a following sea. I would not trust this boat offshore. My Eastern 18 - at 2 feet shorter - is much more reassuring (not to mention cheaper) in a seaway.

As far as semi-planing vessels are concerned, anyone who reads my profile will notice that I own and operate semi-planing hulls and like them very much. However, the claim that small semi-planing boats don't pound I think is a myth. As soon as the waves are big enough to lift the bow out of the water, the boat is prone to slamming at the flatter after sections. Any semi-planing hull that takes waves well usually has a fair amount of vee aft and is therefore functionally the same as a modified vee hull.

I think the Handy Billy gets much of its fuel efficiency from its narrow profile, which is something I want to include in my boat anyway.

~ ALowell

Raggi_Thor

03-24-2007, 06:08 PM

ALowell

03-24-2007, 06:31 PM

I agree, you have to look at other succesful boats to save time.
Maybe this one:
http://www.batliv.com/wip4/bildekarusell.epl?id=96089&offset=1

It's 27 feet, rounded V in front, quite normal V in the aft.

I think this looks promising. Ever since the Wally 118 came out I've seen a lot of the same style bow in other designs. I wonder if it makes the boat handle better in following seas to have the bow knuckle above the water line? More likely this is just styling, since under the knuckle the shape is largely the same as any other boat. Thanks for sending along that link.

~ ALowell

PAR

03-25-2007, 01:51 AM

There are hull forms that will plane at moderate speeds and slice through chop, rather then bash it's way through. These designs were necessary when 30 pounds of engine/drive train weight per HP were common and typically were narrow, drawn out shapes. These were very efficient and sea kindly, but as reliable HP went up as weight of power plants dropped, the requirement wasn't as necessary or marketable so fat butted hull forms swarmed the industry.

I've personally been aboard a Nat Herreshoff steam launch that did 25 knots in a nasty bit of chop and didn't pound a lick. This was his later "inclined bottom" idea and the hull was quite narrow, with a very fine entry. She held her bow about 18" above the water at full speed and moved through chop like it didn't exist.

We can't sell 36' x 6' power cruisers any more so the market is a rare one. If you can't sleep a platoon, get over 35 knots and have impressive phallic(s) hanging off the transom, in a 25' powerboat, it doesn't sell. Logic dictates the form be fine entry, narrow, reasonable firm bilged and light to have efficiency, low speed manners, high speed ability and capable of handling small boat advisories conditions with relative ease.

Your desires, ALowell, are unique enough to require a new design. There may be (I'm quite certain of it) stock designs that will perform to most of your expectations, but I think your needs are specific enough to warrant a custom. It's possible some of your "models" concerning hull form, may need revision to satisfy your needs, but surely a doable thing.

The extreme majority of stock plans available today will try to address as many possible clients, builders, owners as possible. This means a fat, inefficient, over powered, excessive freeboard craft with stylish appointments. If you'd like to contact me (or any other designer) by email, I'm very sure a hull form can be developed that will meet, possibly exceed you needs.

RonW

03-25-2007, 10:53 AM

Par- your post is interesting and informative to say the least.
You are the 2nd. person to mention a nat herreshoff steam launch.
On another forum jay greer mentioned a ride in a 30 ft. herreshoff steam launch that ran 25 m.p.h. not knots, which I find fascinating to say the least.
That is approx. a multiplication of 4 times the square root of the waterline, which is a lot of speed for a semi-dissplacement hull.
That by fars exceeds william hands exspress cruisers, that where suppose to be considered speed demons of the times. His 36 ft. claire ran 22 m.p.h.
I take it that the launch you where in, is a 6 x 36 fter.

I think the baby boomers are getting older and are trying to figure out how to make their boats ride a whole lot smoother and still maintain good speed in rough and choppy water.And to my way of thinking, just about pretty well eliminates a planning hull.

Maybe alowell is asking a lot out of a 5 x 20 ft boat with a outboard. I would think the atkin rescue boat and farmer's piute would come close to fitting the bill in the rough water capabilities, but bigger boats, slightly.
It will be interesting as to where this goes as to size, shape and speed all combined.

--Hey alowell, check this design out. Maybe what you are looking for.
http://bartenderboats.com/19-foot-bartender.html

ALowell

03-25-2007, 04:11 PM

--Hey alowell, check this design out. Maybe what you are looking for.
http://bartenderboats.com/19-foot-bartender.html

I think the Bartender would probably do everything I want. Unfortunately I can't abide the looks of it. However much I protest otherwise, I am very picky about my boat's appearance.

Par:

Are there established formulae that describe the phenomenon of exceeding hull speed with narrow beam? It seems to me that many displacement catamarans do this every day, so I wondered it anyone had done tank tests to quantify it.

~ ALowell

PAR

03-25-2007, 10:41 PM

Alex, there are some formulas, but have a limited range of application.

The Herreshoff I was on was a 6 x 36 foot craft and it wasn't in semi displacement mode, but full up plane. One look at her wake, which was remarkable flat, not rolling or breaking showed her speed/length well into plane. This isn't the only craft to employ these techniques, nor do they have to be 100 year old designs. Several current designers have played with this interesting set of hydrodynamic phenomenon's. I have recently be doing some model tests on low power, high efficiency planning craft. My tests on resistance and power requirements don't have the luxury of tanks, though properly equipped, sometimes with bathing suit donned, I've had good results in a swimming pool.

In all cases, the modern boat buying public will have to change it's concepts and ideas of how a power craft should look. Boats that are near as tall as they are long and 50% beam/length ratios have to be forgotten, in favor of a softer ride and disgustingly good fuel economy. When gas prices hit $5 a gallon in the USA, maybe . . .

raw

03-26-2007, 12:00 AM

Hi ALowl,

Just read through most of the above comments and they seem to be concentrating on speed and slamming aspects of a long narrow deep V vessel similar to that shown in the sketch attachment of your first post.

Have you considered that such a vessel may have less than adequate stability? My first thoughts when I looked at your sketch was that you may* have issues here. I know you mentioned ballast, but is that really the best solution/compromise?

What are your plans/uses for the vessel?

Raw

charmc

03-26-2007, 12:00 AM

ALowell,

Another successful hull type with an excellent record of handling choppy seas while planing at 15 - 20 mph is the Jersey sea skiff. The hull is characterized by a narrow beam, sharp vee with a fine entry at the bow, transitioning to a nearly flat bottom at the transom. Two well known applications of this design philosophy were the early Pacemaker and Egg Harbor sportfishermen, which were legendary for their seakeeping abilities. I rebuilt a 1960 30' Pacemaker myself, and can testify as to it's superb handling in rough seas. With a single engine I had no trouble keeping up with wide beam FRP twin engined boats of similar length, while using much less fuel. Returning from OPSAIL 76 in NY Harbor in the company of several 36'-42' fiberglass boats from our marina, we encountered a stiff onshore wind on an outgoing tide. I was able to throttle back to about 15-18 mph, staying on plane and slicing through the steep seas in an easy, rocking horse motion. At one point I looked around and found all my passengers asleep. That night several of the "big boat" owners talked about how their boats were pounding into the head seas, several folks got seasick, etc. etc. I was caught out in sudden squalls a number of times and never had any doubts about the boat's ability to handle rough seas.

I guess I'm following the lead of several others in supporting your notion of a narrow planing hull with a deep vee entry. You're definitely on the right track. My hull was flat for only the after 25% of its length. A flat or moderate vee shape aft will allow the boat to plane at lower speeds, while the transition to a deep vee forward enables the hull to slice through seas without pounding. I know it's more difficult to build than a constant deadrise, but constant deadrise deep vees only like going fast.

Loveofsea

03-26-2007, 12:40 AM

My motto:

There is nothing like the feeling of utter security on a tumultuous sea~!

i run the seas in a 19ft flatbottom skiff with a tiller. i have logged over 55,000nm of open seas in that skiff and i wouldn't feel comfortable in a V bottom when the seas get rough.

The V entry precludes your ability to induce maximum transom lift which is critical when controlling a boat in severe weather. Also, the standard helm control, (wheel and lever throttle) is clumsy and does not allow for instant lock to lock steering or articulate throttle control. Both of those are of critical importance when the going gets tough. i'll take a tiller over a console any day the wind is up.

FAST FRED

03-26-2007, 07:05 AM

"I think the baby boomers are getting older and are trying to figure out how to make their boats ride a whole lot smoother and still maintain good speed in rough and choppy water.And to my way of thinking, just about pretty well eliminates a planning hull."

If marinas start charging by the SQ FT , rather than LOA , it would do a lot towards having more useful boats than flat water planers.

Of course if the Boomers learn to outfit and equip their boats as Cruisers ,(instead of Dock Queens) no marinas would be needed , only a mooring & a dink plus an anchor while cruising.

FF

tri - star

03-26-2007, 08:17 AM

I am a huge fan of the Herreshoff(s).

So if we are to report on some of the very efficient monohulls, it's also only fair,
to remember who is also the Father of American Catamarans.

Virtual copies of Herreshoff cat designs are still being sailed today.
Whereas, as noted, the 6 ft wide monohulls - tend not to be seen as often.

The New York Yacht Club banned the catamaran from racing. Way back then.
After a Herreshoff Cat:
- totally embaressed, an entire fleet of monohull sailboats.
Annoying the most powerful and wealthy men of the day.
The business side of the family - from then on, wisely, discouraged his brother -
from his passion.
( Wise in terms of winning America Cups and earning a living, certainly.)

The marketplace is finaly changing. Slowly it is true.
We have designed a power cat that does all the things that ALowell requires.
- And I'm happy to add - the vessel was built and SOLD to a happy sports fisherman.
It's hard to argue with this sucess.

The glamour mutihulls have mostly, been all about speed.
With the basic rule of thumb that you only need " Half the HP "
The cat designer, has two options:
- Go for less power and take advantage of the increased economies inherrant.
- Or go for top end.
The Laws of Physics have given you lower resistance than a wide mono.
Combined with higher stabiliy than a narrow mono.
- So you can achieve higher speeds with better behaviour - up to a point.
Those same Laws - demand a price for going Quick.
Irrespective, of the hull chosen.

So for the sport/fish, our focus started at Zero or Loiter speeds.
- Not ultimate velocity.
Next was getting home, in poor weather.
Demanding a sea kindly boat, that only needs reasonable speed.

The result ?
Is a boat that operates effectively, within the parameters defined by ALowell.

' Regards.

Willallison

03-26-2007, 07:18 PM

Perhaps you'd like to post a pic or drawing of this marvellous craft Tri-star...

PAR

03-26-2007, 09:51 PM

I second the desire to see some of these "tri - star" designs. Please enlighten us with your abilities and efforts as you've nothing posted in the design gallery here, nor a quick perusal of your posts indicate a web site or posted image by your hand. I didn't read them all, frankly finding the tone (in most) condescending, therefore not worth further review. Accept my apologies in advance if I'm incorrect in this regard. It certainly will not be the first time I've misunderstood a poster intent or inferred an attitude where there was none.

I do know of several Tri-Star companies in the industry. Tri-Star Marine (Australia), Tri-Star Yachts (Italy), I'm reasonably convinced you're not Ed Horstman (of Tri-Star trimaran fame), nor do I think you have anything to do with MasterCraft's design, so help us (at least Will and I are interested) understand the attitude and tease us with an image of your cat.

tom28571

03-26-2007, 11:21 PM

We might cut Tri-star a little slack to see what he has. I think a displacement cat is one of the most likely candidates for Alowell's goals. Another might be one of the semi-displacement craft already mentioned.

At least, I would like to see the proposed cat, along with you guys. I do agree that too many boats are ruined for many ordinary uses by the demand for high speed.

Willallison

03-26-2007, 11:50 PM

Yeah - don't be too hard on him PAR - I think its just that his NA degree majored in English Literature (hence his somewhat 'floral' writing style) as opposed to English Studies in which we were taught to be as short and concise as possible:D But I'd still love to see the pics;)

I love displacement cats, but if have a couple of reservations in this application.
1st there is the relative complexity of building the boat.
2nd there is the issue of bridgedeck slamming, which can only be overcome by lifting &/or shortening it, which may in turn be difficult on a 23ft boat
3rd, there are pretty tight cost restraints on the build - and cats tend to be more expensive.
My understanding is that the boat is essentially to be used as a commuter - with little in the way of onboard accomodation. My first thoughts would be to go for a slender, lightweight monohull, possibly stabilised.

fcfc

03-27-2007, 09:41 AM

tri - star

03-27-2007, 10:49 AM

To FAST FRED,
" If mariners...." - Ageed !

To tom28571,
"......cut tri - star a little slack..." - Thank you !

To Willallison & PAR
Pardon my pontifications - I will be more abrupt today.

To tease you further:
The boat in it's 25' version - fully loaded, including 3 or 4 large
policemen - was clocked at 37 knots.
With o/b(s) rated at 300 hp.

Along with other presumptions that have been made;
was that the vessel described was a displ. cat.
Not so. Our " Wonder " boat behaves well, with less than
100 hp or more than 200 hp......above 40 - or below 20 knots.
It is not speed limited. It's up to the client.

As to pics....? Why ?
To give people more ammo - to be armchair critics ?
I'm slow to send pics to any one, especialy other boat designers.
I'm not going to do your work for you.

Polite, paying clients in a contractural situation, are of course
a different story.

' Regards.

tom28571

03-27-2007, 02:07 PM

Oh well:confused: It's still an interesting thread even without seeing the Wonder boat. I have not liked teasing very much since an encounter with Anya Johansen in the 8th grade.

Will, at what level of "roughness" does the bridgedeck slamming get to be a problem? Powercats seem to be gaining popularity on this coast with the fishermen. They have to reach the ocean thru an inlet that can be very nasty with a sea breeze and eb tide and just rough at other times. Then they fish in the Gulf Stream, off Cape Hatteras, Cape Lookout and Cape Fear. I don't have much personal experience with powercats though.

We have lots of flat bottom boats locally but they are used mostly for crabtrap work in inshore water. Loveofsea uses his flatbottom boat in the ocean off southern California and prefers it to V bottoms. He must have his good reasons. I know he uses an aft shape to hold the bow down and avoid pounding against the midsections.

I would think that a highly warped plane bottom on a fairly narrow hull would work well in rough water for a day boat or fishing use. As a cruising boat it is no so good since the high deadrise running so far aft would severely limit interior accomodations demand that high superstructure be avoided for stability.

charmc

03-27-2007, 02:38 PM

To tease you further ... Along with other presumptions that have been made ... As to pics....? Why ?
To give people more ammo - to be armchair critics ?
I'm not going to do your work for you.

Sounds like,

"My boat's better than yours."
"No, you can't see it."
"No, I won't tell you why it's better"
"Whatever you say is wrong and presumptuous. You can't criticize or analyze it.....because you don't know the first thing about it...because I won't tell you anything about it"

What's the point of going on a forum, then? Sorry, I don't get it

ALowell

03-27-2007, 05:10 PM

When you look at rescue boats, intended to run fast in heavy seas, you find that they are not particulary deep V or narrow :

US Coast Guard MLB 47 : l/b = 3.5, deadrise 17-20°, top speed 25 kts.

Swedish Rescue Society 1200 (designer R Eliasson) L/B = 2.88 , deadrise 21-23°, top speed 40 kts.

Although I suspect both had extensive studies.

These boats are not within our scope as they are much larger designs (twice as big). Any boat that big will not need as much deadrise simply because they are more massive.

~ALowell

ALowell

03-27-2007, 05:18 PM

Since the thread has begun to consider catamarans, I thought I'd tell people about the ideas I've had over the past few days:

Since the design I want will indeed be a commuter and therefore have little need of space, why not raise the bridgedeck clearance? With this idea in mind I've drawn up some plans of cats with under-deck clearance of 3-4' with LOA at 23'. With a beam of 10' will it be top-heavy? Since the hulls will likely be narrow, keep in mind that the boat will settle considerably when not running and therefore be less top-heavy at rest.

Also, why not make the bridgedeck half of LOA? This would decrease strength but not unmanageably.

I will send along my drawings when I have more time.

~ ALowell

tri - star

03-27-2007, 05:28 PM

To charmac:

Obviously, you have never had a design " borrowed " by others.

Unless copyright protection is fully in place - full discloser is not wise.
That's plain good business.
My data has the authority of real world experience.
It's up to others to refute my claims. If they can...with real world data.
Not a lot of yelling...

As tom28571 says,
" Powercats seem to be gaining in popularity...."
So I'm not alone in this understanding of hydrodynamics.
Except, perhaps that, I've been aware of it since - at least '88.

So if you question my statements - go challange those fishermen,
who have put their money and LIVES on the line. - Face to face.
I dare you to do so.

The reason to contibute ?
Is to steer people, with genuine concerns, to solutions that
work for them.
Not to repeat third - hand info. - as if it was Absolute Truth.

" Regards.

Willallison

03-27-2007, 07:25 PM

Tri-star - you're taking this WAY too seriously. Nobody's having a go at you, we're just interested in your so-called wonder boat. And if the design is so basic that we are able to 'splash' it from a couple of photo's, then there's nothing so wonderous about it anyway....

Tom - bridegedeck clearance is just one of the variables that can contribute to, or eliminate, slamming. Much reading has lead me to the conclusion that a minimum of 900mm (and preferably more) is needed to minimise it. But of course this depends very much on the rest of the design and the sea-state where the boat is to be used. At the end of the day, I guess it's somewhat subjective. I've spent days out fishing in smaller (up to 28ft) planing powercats. I hate them. Sure they're fine once they're up and going, but slow down and it's nothing but thump, thimp, thump.

Which brings me to Alex's comment -
Since the hulls will likely be narrow, keep in mind that the boat will settle considerably when not running and therefore be less top-heavy at rest.

This is only the case for planing catamarans. The displacement cat will not rise percepatably at speed, as there is very little contribution from dynamic lift

tom28571

03-27-2007, 09:01 PM

Tom - bridegedeck clearance is just one of the variables that can contribute to, or eliminate, slamming. Much reading has lead me to the conclusion that a minimum of 900mm (and preferably more) is needed to minimise it. But of course this depends very much on the rest of the design and the sea-state where the boat is to be used. At the end of the day, I guess it's somewhat subjective. I've spent days out fishing in smaller (up to 28ft) planing powercats. I hate them. Sure they're fine once they're up and going, but slow down and it's nothing but thump, thimp, thump.

Which brings me to Alex's comment -

This is only the case for planing catamarans. The displacement cat will not rise percepatably at speed, as there is very little contribution from dynamic lift

Will, I'm never going to get very deeply into powercats or sailing cats for that matter. I do like the speed sensation once in a while but I'm one of the throwbacks that actually likes a sailboat to heel a bit. The feel of a good boat knifing to windward in a good breeze with the rail near down does something that even more speed in a multi just doesn't match for me. I do recognize the great advantages of multis for some uses though. You Aussies do build some very impressive big displacement wave piercer cats. I assume they can make them with bridge decks high enough to avoid the mentioned problems.

Willallison

03-27-2007, 09:13 PM

Will, I'm never going to get very deeply into powercats or sailing cats for that matter. I do like the speed sensation once in a while but I'm one of the throwbacks that actually likes a sailboat to heel a bit. The feel of a good boat knifing to windward in a good breeze with the rail near down does something that even more speed in a multi just doesn't match for me. I do recognize the great advantages of multis for some uses though. You Aussies do build some very impressive big displacement wave piercer cats. I assume they can make them with bridge decks high enough to avoid the mentioned problems.

Yes and no. I remember quite clearly when one of the early wave-piercing Inact ferries ran into the back of a wave and came to a very abrupy halt. It ripped the furniture off its mounts and sent it flying up against the front of the vessel. The bar nearly killed the owner of the company.
They were very different beast back then. Nowadays the centre hull resembles a very deep forefooted monohull, with a pair of wave-piercing hulls tacked on either side. I still have reservations about their suitability in anything much more than surface slop though - even though one held the blue-ribband trophy for some time.

ALowell

03-27-2007, 09:57 PM

My last post was in reference to a planing cat, but one displacement cat I'm considering is the "Eko-Kat" built by Multi Marine (not the Aussie one). The building technique lends itself well to increasing freeboard so that this could be made with seagoing under-deck clearance. Keep in mind that I would build a considerably different supstructure.

http://www.yachtworld.com/core/listing/pl_display_photo.jsp?&hosturl=multimarine&slim=broker&boat_id=1547873&boatname=23%27+Multi+Marine+Eko-Kat+23&photo_revised_date=1161068400000&photo_name=Photo+1&photo=1&url=

For more images go to Multi Marine at: http://www.multimarine.com/boat_sales.html

Click on used boats, then "Eko-Kat".

This boat would get very good gas mileage. The builder quoted me 20mph with 30hp @ 12 mpg. Even accounting for seller's bias, this is an economical boat.

~ ALowell

RonW

03-29-2007, 09:55 AM

Well I had hoped the thread would go a little further on the subject of moderate speed and rough water.

It seems that alowell has decided on a little powercat. I have no experience with these, but from what I understand they are very smooth riding in choppy water. But once you get past the chop and into rough rolling water, that may be a different story.
Correct me if I am wrong, but don't these power cats go back about 50 years to the hickman sea sled.
Most designs do better in the type of water they where designed for, local designs for local waters.
It still is a matter of how rough of water and at what speed.
Of course full dissplacemnet hulls are going to handle the roughest water and give the best ride, but at low speeds.
That is where I have becamed a fan of the semi- hulls, old time launches that run in the mid to upper teens and maybe low 20's depending on the length of the hull. A revival of the launch, that was replaced by the modern high speed planning hull..bang, bang bang...

Then again what about a boat such as the pulsifer hampton...
about 14 m.p.h. top speed. Is that too slow? For rough water capability.

charmc

03-29-2007, 10:45 AM

The feel of a good boat knifing to windward in a good breeze with the rail near down does something that even more speed in a multi just doesn't match for me.

With you there, Tom. Recreational boating, like all recreation, is about creating experiences that appeal to us.

Charlie

charmc

03-29-2007, 11:09 AM

but one displacement cat I'm considering is the "Eko-Kat" built by Multi Marine (not the Aussie one). The building technique lends itself well to increasing freeboard so that this could be made with seagoing under-deck clearance. Keep in mind that I would build a considerably different supstructure.

This boat would get very good gas mileage. The builder quoted me 20mph with 30hp @ 12 mpg. Even accounting for seller's bias, this is an economical boat.

ALowell,

The Eko-Kat appears to be an excellent choice for calm water and chops. Performance might not be exaggerated; look at the Pulsifer Hampton performance quoted for a heavier monohull, the two speed figures seem consistent. If each boat were sold with an attractive woman as shown in photo 7, it would become one of the world's most popular designs! :D

Rough water, to me, is when things start to get out of hand, as in crossing a bar with an outgoing tide and onshore wind, or any situation in which the wind is 20 mph or more and has had a long fetch, as in easterly or NE winds on the Atlantic. I'm not a designer, but I have driven boats into steep seas many times, and here is where I see shortcomings. I can see those twin hulls knifing into a sea without generating much lift, and the bridge taking the full impact. If you decide to use this as a basis for your own build, I'd be sure to extend that small center hull quite a bit, if you intend going offshore.

Charlie

charmc

03-29-2007, 12:22 PM

Obviously, you have never had a design " borrowed " by others. Unless copyright protection is fully in place - full discloser is not wise. It's up to others to refute my claims. If they can...with real world data. Not a lot of yelling...

Except, perhaps that, I've been aware of it since - at least '88.

So if you question my statements - go challange those fishermen,
who have put their money and LIVES on the line. - Face to face.
I dare you to do so. The reason to contibute ?
Is to steer people, with genuine concerns, to solutions that
work for them. Not to repeat third - hand info. - as if it was Absolute Truth.

Tri - star,

OK, from your statements above, it sounds like you're certain you've been the victim of having your design stolen, appropriated, or, like a friend of mine, had a client take preliminary renderings contracted for, hire a student draftsman to complete them, and refuse to pay on the grounds that, "you didn't give us what we wanted, so we don't have to pay you. We "had to" hire the other/cheaper guy to get it as we wanted. If you don't like it, sue us. Our 10 lawyers will be happy to meet your 1 in court.......". Personally, I've had the experience of not being paid by a client for industrial recycling equipment I designed. So yes, I do understand that experience. It sucks.

I understand your reluctance to give too much info. Go back and review; you'll see that I never challenged your performance claims. I did challenge your method of communication, because you're challenging others without giving any data to support your claims. Since you've sold your design to customers who are satisfied, it must be a good design. All I am saying is that coming into a forum, claiming you know more than others without giving any supporting infomation, doesn't accomplish anything.

Earlier I posted a link to the builder of Erie Cats in response to a question posed by ALowell. I don't know that builder, but, from the information he's given, the design looks sound, and performs well in the video. You say you've been designing a good powercat for about 18 years. That's great. As I'm sure you know, Albert Hickman's sea sleds were first designed before WW I. They performed well in rough seas, and the early Boston Whalers were inspired by Hickman's work.

As Will said, if a glimpse of some photos is enough for someone to copy your work...... On the other hand, you're exposed already, unless your fisherman clients are never seen by others, never talk about their boats over a beer, and keep them hidden away in locked sheds in hidden harbors when not in use.

Some comments about why your design works better, even a photo or two, shouldn't hurt you, and may do well in spreading interest in your work. ALowell seems to be serious about building from a proven design that meets his needs. Perhaps he'll end up buying your design.

Welcome to the forum. I've found that people here are, for the most part, sincerely interested in learning more about optimal boats for various purposes. Try not to be overly sensitive about comments made. Like you, there are others here who have earned their knowledge through hard experience, and they want to defend their ideas. The result, of the interchange, hopefully, is that we all learn more, and use the knowledge to improve the boating experience for everyone.

Best,

Charlie

charmc

03-29-2007, 12:33 PM

Well I had hoped the thread would go a little further on the subject of moderate speed and rough water.

Then again what about a boat such as the pulsifer hampton...
about 14 m.p.h. top speed. Is that too slow? For rough water capability.

Ron,

Pulsifer's Hampton seems to embody much of the elements of the East Coast sea skiffs. The lines remind me of the wood hull Pacemaker I described earlier in this thread. I can speak from experience that that design handled rough seas very well (mostly "landlubber" passengers falling asleep while we progressed through steep 6-8' seas one day says something for the easy motion, I think), and planed with moderate power in the 14- 20 mph range. Apart from offshore racers (and even they slow in rough seas, with races called off if it gets "too rough") no one tries to maintain high speeds in truly rough seas. 14 mph would be the upper end of speed for any hull type in heavy seas. The Hampton design does seem to address what ALowell posted at the beginning of this thread.

Charlie

charmc

03-29-2007, 12:39 PM

Another design to be considered is Loveofsea's flat bottom skiff. Since it's description and photos have been published on the Internet and in a magazine, I'll just link to that. He makes some interesting claims, and describes why he believes his design handles rough seas. Since he goes offshore regularly in this boat that he built himself, his ideas are worth reading:

http://www.oceanskiffjournal.com/SubscriberContent/Articles/Vol02Issue01/General/BoatProfile3.aspx

ALowell

03-29-2007, 08:17 PM

I think the Pulsifer Hampton might be a good concept, however it would need to be scaled up for my purposes as the normal 20' version has very low freeboard and doesn't look like something I would want to be in during any kind of survival situation.

Everyone seems very taken with the idea of the Hickman Sea Sled. I've never been convinced about their ride characteristics, though I've never ridden in one so I don't speak from experience. One thing that worries me is that the claims made about Sea Sleds may be out of date. If the claims people often site are in comparison to the boats of the same time period - before the advent of the deep vee - what was considered good performance then might today be surpassed by modern vessels. This is just conjecture on my part so please correct me if I'm wrong. I would be very interested if anyone has personal experience with an inverted vee boat.

I apologize for not posting drawings of my catamaran design. I'm not worried about plagiarism (as seems to be popular), I just can't get my pdf files to download from my hotmail account. In the meantime just imagine a cat about 20' long, 4' high freeboard, 2' wide hulls, about 15 degrees of vee and the deck at gunwhale level to preserve under-deck clearance. This doesn't allow for any accomodations or even seats, but would suffice for a console and railings.

~` ALowell

charmc

03-29-2007, 10:43 PM

Everyone seems very taken with the idea of the Hickman Sea Sled. I've never been convinced about their ride characteristics, though I've never ridden in one so I don't speak from experience. One thing that worries me is that the claims made about Sea Sleds may be out of date. If the claims people often site are in comparison to the boats of the same time period - before the advent of the deep vee - what was considered good performance then might today be surpassed by modern vessels.
ALowell

ALowell,

That's a good point. The guy we both mentioned earlier in this thread, Ken Handman, is designing the Port Erie Cat now, and he has stated that he owed a lot to Hickman and the sea sled. His site has photos and videos of the boat running. I believe the sea sled concept is sound. More validation comes from the fact that Raymond Hunt used the sea sled as the basis for his design of the original Boston Whaler. The difference in performance won't be as dramatic as it was in Hickman's day, but I suppose that's simply because powerboat design has made a lot of progress since 1912.

I was driving back from an errand this afternoon, and passed a boatyard with some powercats out of the water. I noticed that they had some of what you've mentioned, i.e. narrower beam than sailing cats, high freeboard, and a vee section center "hull" obviously designed to limit slamming. Not the prettiest boat I've seen, but it looks like it would perform well in rough seas. If your heart's set on a cat, your own ideas, similar to what I saw, seem pretty solid.

sal's Dad

03-30-2007, 09:18 AM

ALowell, after all this discussion, I'm still not quite clear as to the intended use - though I suspect it's as a Martha's Vineyard commuter... but then why the speed requirement in heavier weather? Seems like the ferry backup would cover you there.

Can you elaborate a bit on your specific requirements, and why your Eastern(s) and Duffy won't do?

Sal's Dad (learned to sail on Buzzard's Bay)

ALowell

04-02-2007, 06:37 PM

Can you elaborate a bit on your specific requirements, and why your Eastern(s) and Duffy won't do?

Sal's Dad (learned to sail on Buzzard's Bay)

It will be primarily used around the Cape and Islands for travel to Nantucket and the Vineyard. The ferry would do just fine, but what's the fun in that? Really I hope to convert my design, if it's proven to work, for cruising around the east coast.

My Eastern 18 is a wonderful boat and I can't say enough good things about it. However, at 18' it's not going to be safe for any really exciting weather. The Duffy mentioned in my profile is actually my uncle's. It is quite efficient and has lots of room, but unfortunately it's not my boat.

I have finally been able to upload some drawings of what I have so far. Please excuse the crudeness of the drawings -- I don't have access to any CADs.

RonW

04-02-2007, 08:09 PM

ALowell

04-03-2007, 01:22 AM

I think you did a real good job on drawing the little man.
As for the boat, it looks as if you will be on it and not in it, not good for rough water. It looks as if you only have less then knee deep on the sides, would be easy for someone to get tossed overboard.

I actually borrowed the man from someone else's drawing in the galleries.

The reason for being "on" the boat instead of in it is to increase under-deck clearance and thereby reduce slamming in rough water. I don't think the actual depth of the sides matters as long as railings of suitable height are provided. I intend to build a more elaborate cuddy and helm station after I'm sure I like the basic hull shape.

~ ALowell

kerosene

04-03-2007, 03:06 AM

I always wondered why tehere are no attempts in reducing slamming on cat's bridge decks. To me it would seem that almost anything would be better than the very flat deck - On my quick 3D sketch I have added small hull-lets on the deck - sure the hitting wave still can't go through the deck and will slam - however the impact should be much more gradual - and with more thought other better design should emerge.
Do people do this?

http://kerosene.smugmug.com/photos/140771122-L.jpg

ALowell

04-03-2007, 04:44 AM

This kind of wave impact mitigation is common but doesn't really solve the problem. Even with a vee or vees, a wave eventually does not have anywhere to go and when it is trapped the resulting pressure increase causes a slam. What I want to test with models is the concept of starting the bridgedeck halfway back instead of at the bows as is usual in commercial designs. This reduces usable space but hopefully would give the bows time to rise allowing the deck to climb over the wave. Half-length bridgedecks are often used on bigger sailing and trawler catamarans, but as far as I know this idea hasn't been applied to planing cats of the size I'm interested in.

On a related note, I've heard people say that the reason Sea Sleds didn't have this problem was because they trapped water and air between the hulls, thereby making a compressible mixture and cushioning effect. Has anyone else ever heard of this theory?

~ ALowell

RonW

04-04-2007, 07:57 PM

Alowell, if you are dead set on a power cat, here is a set of plans to look at, can be built from plywood. The previous page does have a write up about performance.

http://glen-l.com/designs/hankinson/wildcat-sport.html

But with that said, in my humble opinion they are going to be great in choppy water, but when it gets rough, and they have to slow down, I think they are going to ride just like a big pontoon.
That's where I say there are better designs for rough water in the semi-dissplacemnet hull area, that can still have a fair turn of speed.

Gilbert

04-05-2007, 12:32 AM

I have been following this thread with a lot of interest. It seems to have settled on the power cat concept, maybe.
I thought I'd mention a hull shape that I saw some years ago that is not quite like any that have been mentioned. The boat was a Uniflite gill net boat that was fishing on Cook Inlet. I saw it before it was launched at the beginning of the season and thought to myself that it looked like a power robbing shape if I ever saw one. It was a 32' boat and the forward portion of the hull was very deeply veed and the fairbody line swept up very dramatically as it approached the area where the propellor and rudder were located in the stern, terminating in a very flat area there at the level of the chines. Someone told me it had a 230 hp engine. Later in the season I saw the boat running in some pretty sloppy weather and it ran beautifully and was making very good time, certainly much faster than I originally supposed it would go. Sorry I don't have hard data for you, but it impressed me a lot. I am not aware that Uniflite made any of their pleasure boats with a bottom shape like that.

ALowell

04-05-2007, 10:31 PM

If I went with a semi-displacement hull I would be interested in something like the Hereshoff power boat. Does anyone know where I can find lines drawings of his power designs?

~ ALowell

RonW

04-05-2007, 10:37 PM

Gilbert, hull lines kinda like this.....

http://www.boat-links.com/Atkinco/Utilities/images/Ketewomoke-3.gif

Gilbert

04-06-2007, 12:41 AM

I thought maybe someone would ask for a drawing so I spent a little while playing with freeship this morning. I am quite confident that I have captured the shape below the chine reasonably accurately. Perhaps the chine and sheer were fuller in the bow and the transom corners may have been radiused but it's good enough to convey the basic idea. Freeship says the prismatic as drawn is .54 which may explain why I was fooled about how much power it would take to move it along.

ALowell

04-06-2007, 05:44 PM

Gilbert:

I've toyed with that idea myself and from what you said it sounds like it works well. The hull you drew takes advantage of lots of vee forward while still having flat aft sections to provide lift. Where it differes from most conventional designs is that the forefoot is deep enough to stay in the water at speed.

Do you think you could mail me a copy of that file? If so send a message and I'll get back to you.

Thanks,

~ALowell

RonW

04-06-2007, 07:19 PM

The hull form that gilbert shows is a full dissplacement hull, and a 35 footer or so would scoot along at a little over 10 m.p.h. or so, depending on power.
Here is the same hull shape in a 24 footer, the noyo trawler by glen-l, it is a full dissplacement hull with a cruising speed of 7 and max of 9.
It seems that these conversations of fair speed in rough water always goes from all kinds and deviations of planning hulls, right back to rougher water capable full dissplacement hulls, but somehow or other the semi- hulls get ignored. Maybe there are so few of them, or they have taken a back seat to the planning hulls for so long, that most people don't fully understand or appreciate them for what they are and can do.

http://www.glen-l.com/designs/workboat/workboat-images/dsn-noyla.jpg

Gilbert

04-06-2007, 07:52 PM

I am no stranger to estimating speeds of boats. It is my considered opinion that the Uniflite gillnetter was doiing over 20 mph when I saw it running in the bad conditions I mentioned. And I don't believe it was running at full throttle either. However, I could be wrong about both those things; but I bet I am closer to being correct than someone who didn't witness it. So it is not a full displacement hull form but at least a semidisplacement form. I would be very interested I hearing from someone who actually has one or had one or just knows exactly what it's performance parameters are.

Gilbert

04-06-2007, 11:39 PM

I decided to upload the freeship file so anyone who is interested can take a look at it.

Gilbert

04-07-2007, 11:37 AM

One more thing comes to mind as to estimating how fast this hull might go. A long time ago when I was first exposed to Crouch's formula I thought "What a useless, strange formula this is. It doesn't even take into consideration the length of the boat or any information about the shape of the bottom or anything else except the displacement!" So I never really used it in any calculations.
Some time after witnessing the underwater shape and the performance of the Uniflite gillnetter I still had no mental frame of reference to explain why it should perform so well. At some point, using an estimate of displacement, I tried Crouch's formula and it seemed to fit right in.
Using a mid range constant of 190 and the above freeship model's displacement and 85% of the 230 hp we arrive at 20 mph.

Crouch's formula
mph = C (constant between 180 and 200) divided by the square root of (displacement in pounds divided by 85% of the rated hp)

RonW

04-07-2007, 02:08 PM

Gilbert, I took it for granted from your line drawings that the hull shape was a full dissplacement and according to length might squaek into the low teens or so.
But if it is actually a semi- dissplacement or semi- planning hull, which ever phrase one wishes to use, and if it was 36 ft. long (for example) it should easily do 18 knots or a little over 20 m.p.h. and maybe even more.
I believe the semi- hulls have a lot to offer in sea keeping and smooth solid riding boats, just at lower speeds, but still at least twice and more the speeds of the full dissplacement hulls.

ALowell

04-15-2007, 11:17 PM

I hope this thread isn't dead yet because I've found an interesting hull-speed boat that I think people might like to see.

This is called the "Allweather 26" and is designed for ultimate survivability and efficiency. According to the manufacturer it uses less than 1/2 gph at about 6 knots. The builder reports 12-20 mpg at reasonable speed. Among other unique features it has a keel-cooled engine and dry exhaust. These alone set it apart from any other production cruising boat and greatly improve reliability and simplicity. With 600 lbs cement ballast and a low CG, this boat achieves positive stability to 120 degrees.

http://www.allweatherboats.com/sitebuildercontent/sitebuilderpictures/awpic2.jpg

http://www.allweatherboats.com/sitebuildercontent/sitebuilderpictures/AW26drawingforweb2.jpg

One of the features I like about the boat - though it's something that could be incorporated into any boat - is the inboard-mounted bow railing that is typical of pilot boats. This allows a person to easily board other boats and step onto docks, etc.

If the Allweather really has 120 degrees of stability I would suppose it is close to self-righting. If it rolled would the cabin and windows survive or would they need to be reinforced?

~ ALowell

charmc

04-16-2007, 01:03 AM

I am no stranger to estimating speeds of boats. It is my considered opinion that the Uniflite gillnetter was doiing over 20 mph when I saw it running in the bad conditions I mentioned.

Gilbert,

I believe your speed estimate. The Uniflite 31 hull was well known as a great seakeeper. I once saw a 50' cruiser attempt to go out through Manasquan Inlet, NJ into the Atlantic during a pretty nasty noreaster with steep 8-10' seas. They were banged about pretty badly, turned around, and barely made it back in, after sustaining damage, although they never went more than 8 - 10 knots. About 10 minutes later, a Uniflite 31 sportfisherman made the same run and disappeared into the distance, on plane at around 15 - 17 knots. Obviously, operator skill was a big part of the difference, but the Uniflite hull had no problem maintaining a good speed in very heavy seas.

FAST FRED

04-16-2007, 05:39 AM

Displacement boats usually need extra stability (flopper stoppers or active fins) and 100 to 200% of the normal power to progress in heavy going.

Many just dont have the reserve power.

Semi and full plaining boats will gain stability while running fast , so do better in heavy going , IF the ride isn't too rough for the operators to stay intact.

FF

RonW

04-16-2007, 03:11 PM

Allowell- your thread took a turn and got even more interesting.
You started off with a power cat at 3 times the speed. Appearantly you have decided the rough water quality of the boat became more important then the speed factor.
For a minute I thought you posted pictures and diagrams of the bartender.
That is a neat little boat, the righting arm is great, and fuel economy is as good as it gets. So are you or will you be happy with the greatly reduced speed, and does the boat have enough room and or is the layout to your satisfaction.It is interesting as to how people start in one direction and as they really refine their most important features, how they end up changing, and sometimes dramatically. I bet that little boat can take some waves that no one in their right mind would be out in.

ALowell

04-16-2007, 04:18 PM

That is a neat little boat, the righting arm is great, and fuel economy is as good as it gets. So are you or will you be happy with the greatly reduced speed, and does the boat have enough room and or is the layout to your satisfaction.It is interesting as to how people start in one direction and as they really refine their most important features, how they end up changing, and sometimes dramatically. I bet that little boat can take some waves that no one in their right mind would be out in.

How do you know what the righting arm is, or are you referring to the Bartender?

You are right that I have significantly changed my priorities. However, I've known about this boat for a few years and my preferences seem to sway between planing and hull-speed pretty frequently. I guess I'll just end up buying whichever I happen to be interested in at the time of purchase, because I don't seem to be completely satisfied with either.

My real concern with this boat is that at 6 knots I won't even be over the horizon after an hour of travel, whereas at 15 knots I'd be at my destination by then! Do people in hull-speed boats have to wear straight jackets?

~ ALowell

kach22i

04-16-2007, 04:38 PM

On a related note, I've heard people say that the reason Sea Sleds didn't have this problem was because they trapped water and air between the hulls, thereby making a compressible mixture and cushioning effect. Has anyone else ever heard of this theory?

~ ALowell
I've been doing some thinking on this in a related topic, hovercraft and cushion height. You can come off cushion if a wave or wake is large enough to come up underneath you and the crest lifts the bottom of the hull. The hovercraft tends to follow the wave down into the trough bottom and gets overtaken in displacement mode.

The only cure is a larger hovercraft with higher cushion height. It would be nice if the bottom of the hull could be shaped to deflect as in the blue catamaran illustration on page 5 by "kerosene".

http://www.drbeach.org/drbeach/pulse.htm
http://www.drbeach.org/drbeach/pictures/wave.gif

http://www.globalsecurity.org/military/systems/ship/beginner.htm
http://www.globalsecurity.org/military/systems/ship/images/design4.gif

ALowell

04-16-2007, 04:52 PM

RonW

04-16-2007, 04:53 PM

At 6 knots it will take 3 hours before you are over the horizon, that makes for being able to wave good-bye for a loooong timeeee....

I think as far as a full dissplacement hull, you have to always be in very rough water, or be very highly intelligent, as to always contemplating technical thoughts for hours, or just too stupid to ever think about anything, to be able to stand the high speed effect of 6 knots in a power boat.

That is why I have such a interest in seeing the revival of the old time launches, or more of the semi- planning hulls, that give you a little of both worlds. The boat rides smooth in choppy water, but yet still cruisers at the mid teens or above according to size.
If you want to build a wooden boat, there are some great old time designs on the atkin site.

ALowell

04-16-2007, 05:00 PM

That is why I have such a interest in seeing the revival of the old time launches, or more of the semi- planning hulls, that give you a little of both worlds. The boat rides smooth in choppy water, but yet still cruisers at the mid teens or above according to size.
If you want to build a wooden boat, there are some great old time designs on the atkin site.

I don't love the Atkin designs because of the complex shapes involved in creating the propeller tunnels. This would greatly complicate building and would definitely require building molds which is something I want to avoid. Also, none of them look like they are prepared to take on truly nasty weather, though I might be wrong.

What I keep looking for is one of the launches that people have mentioned built by Hereshoff. I can't seem to find anything useful online.

~ ALowell

RonW

04-16-2007, 05:07 PM

If you are disscounting the atkin designs due to the prop tunnels, those are only on the sea bright skiffs, he has tons of other plans.
Look at the inboard utilities and inboard cruisers.

http://www.boat-links.com/Atkinco/

There are plenty of old time semi-planning hull designs.
Literally dozens to pick from, and a lot of these can be altrered as to layout and some can even be changed to outboards.

RonW

04-16-2007, 05:12 PM

Here is a launch, I even have the plans for it.
Then there is the ketwomoke, utility, both rough water boats, no prop tunnells.

http://www.boat-links.com/Atkinco/Utilities/Pennant.html

Actually the ketewomoke and utility is nothing more then a larger version of richard pulsifer's hampton.

kach22i

04-16-2007, 05:18 PM

Aren't hovercraft pretty uncomfortable in waves due to heaving? I considered an SES as a solution to my design problem but I abandoned the idea because of what I read about heaving. I still wonder if this could be solved with expandable air chambers that would temporarily expand to take up excess pressure when encountering a wave. High-rate springs would then collapse the chambers when the wave passed thus preparing for the next wave pressure spike. If that doesn't make sense maybe I need to draw a picture.... Anyway, it's much more R&D than I can tackle at this point in my life.

~ ALowell

You might find this thread interesting, I sure did, Look for posts by BMcF.

Link:
http://www.boatdesign.net/forums/showthrea...6210&page=2 (http://www.boatdesign.net/forums/showthread.php?t=16210&page=2)

Sample regarding SES (and hovercraft):
You need only to supply massless air. Fortunately for my pocket book, the workable solution actually involves lots of fancy hydraulically-operated hihg-response cushion vent louvers (and/or variable-geometry lift fans) and a detailed knowledge of the spatial pressure responses, particularly those that are acoustic, and the ability to build a controller that can effectively resolve the whole mess through various filters originated by Kalman and others and kill the fundamental heave-bounce mode of the rather lively spring that is known, oxymoronically, as an air 'cushion'. (whew! that was a long sentence..) A 'cushion' it ain't...

BMcF is Bill McFann of Island Engineering.
http://www.islandengineering.com/

Geoh

04-16-2007, 10:10 PM

Hello ALowell

I just bought the allweather boat 1982 model. I just finished painting the boat. I will have it in the water this week..Putting it in lake Mohave here in AZ Then if no mechanical problems trailering it to the Sea of Cortez.
There were only 32 made and none since the late 90s

George

longliner45

04-16-2007, 10:42 PM

hey guys look at this and tell me what you think,,(powerand motoryacht,com,),,,,,,,,,,,,look up boat test31jcboat,,,,and read the specks ,,,,thanks ,,,,,,,,longliner,the boat featured is called the boxer

Geoh

04-16-2007, 10:48 PM

testing attachments
Less than a mile from the Colorado river, in the old days i cudda just floated on down stream to mexico...

George

longliner45

04-16-2007, 10:51 PM

nice lines man

Alan Mikkelsen

09-18-2007, 02:44 PM

testing attachments
Less than a mile from the Colorado river, in the old days i cudda just floated on down stream to mexico...

George

So how did the tests go? I saw one of these boats in Alaska and they really iimpressed me.

Geoh

09-18-2007, 08:10 PM

Hello Allen
Spent 2 weeks on Lake Mohave...40 plus hours trying to break something...
Engine and all mechanical fine...29 hp Perkins 3300 wot 8 mph 2500 rpm to 2700 seemed to move it along 6.5 to 7 mph ...over 3000 it wanted to run a little hot after a while...
Gonna change all the fluids and filters and it still has about half a tank of old fuel to get rid of or cleaned up before i take it out to sea...
engine specs 3600 wot original props were 17 10 but the one on my boat was put on by last owner in early 1997 is 14 9 I bought the prop book and by all the numbers the 14 9 is correct size but looks like a toy on the boat. Got a gut feeling that the 17 diameter prop is what works best in rougher seas and weather...only looking for hull speed of 6.5 knots.
Redid the interior white paint on all interior exposed fiberglass and Home Depot had some Mahogney real hard wood prefinished flooring that i paneled the rest of the interior with...new formica counters...Now I can have the "yachting crowd over for cocktails"

Here is a site http://www.itsuro.com/boats.html about a trip to Alaska this summer on the inside passage in a boat almost exactly like mine...
I am still an Alaskan resident so plan on registering it in Ak rather than AZ so i can paint "Homer AK " on the stern as home port...Homer Hughes is the boats builder... http://allweatherboats.com/

George Hood

Alan Mikkelsen

09-18-2007, 09:42 PM

Sounds great. Thanks for the link. How did you find your boat? They're not exactly very common.

Geoh

09-18-2007, 10:11 PM

craigs list

kengrome

09-19-2007, 02:31 AM

ALowell, it has been 5 months since you created this thread. What is your current status? Have you selected a boat to build or are you still considering alternatives? If you have selected a boat which one is it?

Alan Mikkelsen

09-21-2007, 10:05 AM

Geoh

09-21-2007, 03:49 PM

Hi Alan
The engine is a 1987 3 cyl parama M30...Volvo Penta now builds them as 2030 penta...
My next step will be to clean the heat exchanger as it looks like the previous owner might have been using auto antifreeze rather than the recomended type...
I just got my truck shipped dn from AK so now i can get serious about getting on the water...Also temps here in Bullhead aren't 110 to 120 anymore...

George

Landlubber

09-22-2007, 01:27 AM

Have to agree with Safewalrus here fellas, going from the "original" text, I too was amazed to read about "My goal is to travel without concern for weather. "
This is usually a comment posted by someone that knows NOTHING about the sea.
So forgive Safewalrus from his comments, he was commenting on the original text, and I can only agree with him.

ALowell has now commented further, so all bets are off.

Geoh

09-22-2007, 05:44 AM

A man that does not fear the Sea will soon be drowned, for he will be going out on a day when he should not. But we, we fear the Sea, and we only be drowned now & again."

I found this quote quite a while ago and now forget where it is from....anybody know?

George

ALowell

09-25-2007, 10:48 PM

Hello everyone. I'm back after a too-long hiatus and we all have George to thank for reminding me about my thread.

My statement regarding "travel without regard to weather" was meant as a relative statement. I assumed all knowledgeable readers would realize that what I meant was not hurricane or gale conditions but rather the day-to-day chop/wind that prevents most boats under 30' from going out comfortably or long distances. I was unclear and that is my fault. To those of you who still think I "know nothing of the sea": this could very well be true since that too is a relative statement. However, I would like to mention that I am a USCG licensed captain (100 tons limited, soon to become unlimited). Also my absence from the forum is in part because I have been cruising aboard a 35' lobsterboat for the past two months, going to Nova Scotia via the Erie Canal, St. Lawrence, and back home along the Maine coast (I encountered lots of weather and regarded all of it).

As concerns progress toward my future boat, I have been researching VSV boats like the "MarySlim" designed by Adrian Thompson and drawing lots of pointy boats in my spare time. The size envelope of my proposed boat has increased over the months up to 28' and seems to be getting larger by the minute. I will probably resort to making a smaller version (15' maybe?) unless I feel very confident in my predictions.

My research thus far has lead me to the conclusion that narrowness will make up for the reduced planing efficiency of extreme deadrise. I have yet to determine if and how much ballast will be needed to keep my VSV right-side-up or if said ballast will negate efficiency too much. I'm also considering water ballast (empty while planing) and lift strakes designed for dynamic stability.

When I refer to "efficiency" it should be noted that I am basing my approxiamate requirements on my present boat which weighs 15,000 lbs loaded and gets about 8 gph @ 15 kts. Anything significantly worse than this will be too much for my wallet and my conscience.

~ ALowell

kengrome

09-25-2007, 11:44 PM

The size envelope of my proposed boat has increased over the months up to 28' and seems to be getting larger by the minute.In this case I will suggest the boat I did not suggest earlier when your length limit was only 23 feet -- Phil Bolger's Slicer:

http://www.duckworksmagazine.com/05/excerpts/maib/1/index.cfm

This is a planing hull boat that bridges the troughs between the waves and gets exceptional mileage with a very small engine.

I might also suggest one of the tunnel-stern Seabright skiffs from William Atkin. His "Shoals Runner" is the last and therefore the most refined of these boats, and it happens to be 22 feet long so it is well within your original design specs of 23 feet or less:

http://www.boat-links.com/Atkinco/Utilities/ShoalsRunner.html

ALowell

09-26-2007, 12:14 AM

kengrome

09-26-2007, 04:12 AM

kengrome

09-26-2007, 05:42 AM

"Slicer" is an amazing looking boat -- I would be proud to own one. However it says right in the description that it handles poorly in waves over 3 feet. My comparatively small 18' Eastern can handle more than that.

Okay ... but I do not recall any mention of this requirement in your design brief. Maybe you can post a new design brief since you've apparently changed it quite a bit. Then we will know better what to suggest and what not to suggest.

Do you have any experience with Bolger's boats?Not personally, but there are hundreds who have, and I suspect that many of them are subscribers to the [bolger] Yahoo group.

ALowell

09-27-2007, 05:09 PM

Okay ... but I do not recall any mention of this requirement in your design brief. Maybe you can post a new design brief since you've apparently changed it quite a bit.
Actually, if you've been following the thread you would remember all the controversy over my "ability to travel without regard to weather" statement that has caused me so much grief. I think this covers more than 3 ft waves, but that is a matter of perspective I suppose.

My new design brief is as follows:

Size: 25 to 35 feet with accomodations for one person (me) and a settee berth for an unwanted guest.

Shape: Very narrow with extremely sharp forward sections and low forward displacement to reduce vertical acceleration in heavy sea. Ability to maintain 15 kts speed in force 5/6 conditions.

Misc. features: Reinforced windows (with easily deployed emerg. covers), low center of gravity, possible water ballast, forward crash bulkhead, helm at pitch center (for crew comfort), propeller guarded by skeg and grounding shoe, minumum 18 in wide side decks for easy access forward, inboard handrail ("coast guard" style), aggressive non-skid decks and large rubrail and toe rail. Plus all the things I'm forgetting.

Things I don't want: Teak and holly sole, flybridge, cupholders, bow thruster, refridgerator, swim platform, jets (or outdrives), folding cleats, bow sprit/pulpit, rod holders, anything to do with "bait", window curtains, glossy gelcoat, "sunpads", European styling.

~ ALowell

Alan Mikkelsen

09-28-2007, 09:45 AM

Other than speed, you're describing an Allweather 26

kengrome

09-28-2007, 09:47 AM

Other than speed, you're describing an Allweather 26So since the Allweather 26 does not fit his requirements, what does?

Geoh

09-28-2007, 11:04 AM

The Allweather layout with a squared flatter stern rather than double ender and more of a semi disp. hull shape ...the weather sorta determines your speed anyway, not gonna be comfortable in under 30' boat in slop at 15 knots...
Also better rethink not having a "cup" holder" sure saves on the spilt beers/coffee...
George

juiceclark

10-07-2007, 08:30 PM

I posted earlier with skepticism. However, since then an idea has come to mind. I used to have a Wellcraft Airslot and loved the way it would catch air over 30mph and lift the hull to where only the very fine entry at the bow was hitting the waves. It was something like this but more primitive:

http://www.boatdesign.net/gallery/showphoto.php/photo/9182/limit/recent

So, here's my idea: If you make the sponsons on the sides much larger...with torpedo shaped bottoms.(use bulbous bow models) Then, you have to make the hull itself really dedicated to trapping air. So, at speed the hull really wants to keep a cushion of air between itself and the next wave.

Lastly, and this is the trick, you have to design the sponsons to move independently of the hull. In other words, the sponsons become like the suspension of a car. The sponsons hit the waves like your tires, a suspension system attaching them to the hull takes the bulk of the shock and the hull does its best to stay above the waves on a cushion of air. The hull could still grab the water in turns and at slower speeds - so it wouldn't handle like the cat-hulls I detest. Stick an Arneson surface drive with a long shaft on that baby and haul ass.

The "Airslot" design is really being taken to extremes now:
http://www.boatdesign.net/gallery/showphoto.php/photo/9265/limit/recent
However, I've yet to see one with a suspension system.

I wish I knew how to draw many of the weird ideas I get from time to time. But my degree is in finance...not engineering. So, I hope one of you can run with it.

Tony
Fort Myers, FL

DanishBagger

10-07-2007, 11:36 PM

Things I don't want: […]European styling.

Being a european I am always amazed at what americans call "european styling". Most times it seems to refer to a sort of style that a certain type of americans thinks are "stylish" and especially "sophisticated". The thing is, that that sort of styling have very little bearing on anything in the real Europe. Glossy man-bags, for instance. Huge ginpalaces in the Med and so forth. Caps and "european" shorts on 60-yo men etc. You can always tell when it's an american walking around being "european".

:P

Sorry to be off-topic, carry on :p

ALowell

10-08-2007, 02:18 AM

The hull could still grab the water in turns and at slower speeds - so it wouldn't handle like the cat-hulls I detest.

What makes/models of cats have you been on and what did you detest?

juiceclark

10-08-2007, 02:56 PM

I've been on most of the smaller ones and, to be concise, in big seas I'd be terrified at speed. I don't like the way the lean in turns either. Most recently I joined a friend on his 48' Ameri?? (forgot name - help) to the Bahamas. It was rough across the Gulfstream and the boat just handled funny. It shuddered and wiggled and then would bang when a wave would smack up underneath.
I think we would have been much more comfortable in a flatter bottom regular hull with a very sharp entry. We would have had a lot more room that way too!

tom28571

10-09-2007, 09:40 AM

Being a european I am always amazed at what americans call "european styling". Most times it seems to refer to a sort of style that a certain type of americans thinks are "stylish" and especially "sophisticated". The thing is, that that sort of styling have very little bearing on anything in the real Europe. Glossy man-bags, for instance. Huge ginpalaces in the Med and so forth. Caps and "european" shorts on 60-yo men etc. You can always tell when it's an american walking around being "european".

:P

Sorry to be off-topic, carry on :p

An off topic may need an off topic reply. Who knows what anyone means by a statement of style or taste?

However, it is true that the current styling trend in boats to make them look more like Nike running shoes did come from Europe. A poor choice of imports in my opinion. Opinions are personal, but there it is:D

charmc

10-09-2007, 04:35 PM

Lastly, and this is the trick, you have to design the sponsons to move independently of the hull. In other words, the sponsons become like the suspension of a car. Tony
Fort Myers, FL

Hi, Tony,

This was posted in another thread recently. Called WAM-V Proteus. Different from the Airslot concept, but a sponson design with suspension system.

DanishBagger

10-09-2007, 06:57 PM

An off topic may need an off topic reply. Who knows what anyone means by a statement of style or taste?

However, it is true that the current styling trend in boats to make them look more like Nike running shoes did come from Europe. A poor choice of imports in my opinion. Opinions are personal, but there it is:D

Haha, okay. But who's to say, that those european companies are even styling it "european"? Perhaps they styled it that way so they could it sell it to the manbag-carrying "sophisticated" americans? Not to the rest of us, europeans as well as americans.

Anyhow, I didn't mean to hi-jack anything, it just seemed that most things with the "european" design is mostly sold in the US (and to the newly rich russians, for that matter). That means – to me – that it isn't really something particularly european, but a style labeled as "european" because in that label there are some connotations of "sophistication", "stylish" "Old World", "tried and true" and so forth. But in the end, it seems to have been overeploited as a marketing tool. So much so, that it has little bearing on the real Europe.

If that makes sense …

RAY TOSTADO

10-09-2007, 07:20 PM

What you are proposing is something mid way between a rider-less surf board and a mini-sub. The hull form that would promote the speeds you require is not the same hull form that is proper for heavy seas. That is until you reach OAL of 50+ feet.

Planing in high seas is a death wish, or somthing close. Lot's of fun, but with dire consequences when the rudder ventilates. To plane a 26' boat requires a flat bottom and lots of sail area.

To break through 12'+ waves requires a slim narrow entry with water tight hatches and ports. Not too much sail given a proper angle to the wind.

Ray T

tom28571

10-09-2007, 08:14 PM

Haha, okay. But who's to say, that those european companies are even styling it "european"? Perhaps they styled it that way so they could it sell it to the manbag-carrying "sophisticated" americans? Not to the rest of us, europeans as well as americans.

Anyhow, I didn't mean to hi-jack anything, it just seemed that most things with the "european" design is mostly sold in the US (and to the newly rich russians, for that matter). That means – to me – that it isn't really something particularly european, but a style labeled as "european" because in that label there are some connotations of "sophistication", "stylish" "Old World", "tried and true" and so forth. But in the end, it seems to have been overeploited as a marketing tool. So much so, that it has little bearing on the real Europe.

If that makes sense …

This bus is not going anywhere I wish to visit so I'm not getting on.

DanishBagger

10-09-2007, 08:19 PM

I didn't ask for you to tote any manbag …

FAST FRED

10-10-2007, 06:00 AM

it just seemed that most things with the "european" design is mostly sold in the US

The "EURO styling" seems to be on domestic built cheapos where dockside VOLUME is the prime concern.

Hinkley and Hood don't build Nikes ,

but Bayliner , Carver , Sea Ray turn them out by the gross.

Gross Blob boats! At least they have little longevity , so are soon gone.

FF

DanishBagger

10-10-2007, 07:47 AM

Exactly that was my point, FF!

Landlubber

10-10-2007, 05:27 PM

We call them Caravans on the water.

juiceclark

10-11-2007, 09:43 AM

Charlie,
Now that's cool! The image in my mind's eye was not as...well...War of the Worlds like!! If sponsons had shock absorbers and moved vertically, you could have a water car slide smoothly over one footers. Maybe an aqua SUV would make a smooth ride over two footers....but big seas are for displacement hulls.

oldcroc

10-16-2007, 10:54 AM

Hello I have been following this thread a while, as the Idea of your Ideal boat has now grown in size eg 35 LOA that can handle force 5/6, or cat B it sounds more like a work boat hull with the bare basics is required, here she is in both mono hull and cat formats they will within reason make any size you want, watch the videos this will do more than you require. http://www.safehavenmarine.com

juiceclark

10-17-2007, 08:46 AM

Lotsa money...obviously marketed to the military.

http://www.hydrolance.net/page5.htm

oldcroc

10-17-2007, 08:19 PM

The strange thing is "no" it is not a navy based boat!! You want? Go buy, This may answer your question though boats are not cheap over here in UK to put it polietly we pay through the our bottoms to have anything worth having! those hulls are freely available,they are available to anyone at any stage of build. you want a hull you can have one as is, or finish it yourself,you want a finished boat you can have one, they will do anything within reason inside.
I have now been looking at boats for about 3 or 4 years or longer most likley trying to nail down my ultimate design, its a trade off all round there is no such thing as THE right boat!!!! I am waiting and watching the growth of the nordhavn on their site hull has just come out of the plug http://www.nordhavn.com 75' long range sport fisher as that is my want,with massive range to sport fish around the world, BUT! I already want to make it a desiel electric, "a la" a 72 on their own site, seem's right and makes sense they have a 72 ocean crosser built and running (English owner) anybody got any stats on that boat yet? range? fuel savingings etc? big claims, seems logical at this stage with the fuel cost looking to go through the roof next 20 years, plus the involvement of big european players motor wise, Siemens, is not that small and has been producing electric drive motors a few years, all be it, for buses here in uk, which have been running for a few years, and still work hope this answered your e-mail enquiry. Regards Glyn

juiceclark

10-18-2007, 09:34 AM

Glyn,
I've been thinking about diesel/electric lately. For speed, I want to put a single, 800hp CAT in the 46' sportfish I'm building. But flanking on each side I want to consider a generator to run a couple of the biggest electric sail drives I can find. (sail drive so the can be pulled out of the water when running)

I'm not sure how it will work...but maybe we should start a new thread to see what the geniuses think?!

Tony

p.s. I don't understand Nordhavens! All the fisherman up in the North Atlantic prefer a very wide platform so it sits right in big seas. For example, the guy building this boat for me fished out of Chesapeake Bay for 25 years and swears by this design:

http://www.boatdesign.net/gallery/showgallery.php/ppuser/22690/cat/500

RAY TOSTADO

10-18-2007, 10:36 AM

A word of caution in today's business world. Yes, I am a cynic, but well founded after 47 years in film production. Take care how you accept any device solely on it's application by a government agency. Be it military or civic buses. Those entities are famous for failures that just keep running on when you just keep pouring tax money at them. "Friends" get the contracts irrespective of quality.

Today a person has to be more sophisticated and have trustworthy contacts. The word of the fisherman stands taller than any evidence of a bus going down the street and talking with the maintenance supervisor for the city bus system.

As for diesel/electric drives one should study up on the current efficiency tables offered by manufacturers. D/E trains evolved as such out of need. And did such at a time when diesel was $.05 a gallon and gasoline at $.11 a gallon.

Check out where modern trains get their power source. It is more cost practical now to "electrify the line" than it was decades ago.

In time the "green" thing will shut down the pollution of the multi engine freight trains of today. But the new diesel designs will be here soon.

Pound for pound and size to size I prefer a hydraulic drive using a diesel pump system. At one time hydraulic motors had a 18% loss factor. Today, the better drives have reduced this to just 8%. They are more linear as how the torque is immediate based upon psi. But yes, hydraulics tend to emmit noise. The cost factor is about 5:1 cheaper for hydraulic drives Vs. electric.

Ray

And I just do not feel at ease with the amount of amps and volts your project will require. Just me. This is not a land bound locomotive. Too much wet air around a boat.