Moderate Speed... Any Weather

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.

 

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.

 

"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

 

20knots in Chop

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.

 

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

 

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.

 

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.

 

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 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.

 

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.

 

Pardon my Pontifications

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.

 

Oh well 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.

 

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

 

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

 

Catamarans

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

 

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.