Please knock down stupid idea

[VT-tuna]

Hi all,
Been reading over this site for a short while now. I am an offshore fishing fanatic in the midatlantic (east coast of US). Long and rough rides to the fishing grounds are the norm.

I have this silly idea that a boat (sportfishing) could be built for fast and comfortable ride out (yeah right). I have it in my mind that a light weight hull(thinking aluminum) could be built such that it actually rides on muliple jet-ski like sub hulls that perhaps are connected through a dampening device (i.e shocks). When on plane, primary hull would basically be out of the water and the sub (jet ski) hulls would be planing or even pushed through a wave. I picture this as each sub hull possessing a jet drive exhaust. I also see these as getting their water flow from one large diesel engine and pump that supplies the flow to each sub hull jet from a cental location in the main hull.

Lift is acheived via planing subhulls, jet angle (fore and aft locations) and part of primary hull at aft for water intake.


As an electrical engineer with controls and machinery background (and of course boat owner all my life), it just seems possible to build a light weight, basically fitted sportfishing boat with such a setup. 40 foot range with single 800 hp diesel with speeds of ..... well I want embarrass my self too much just yet.


Please point out the basic boat design physics that insist this vessel will simply sink or at best push water to 5 knots.

[stonebreaker]

Wouldn't it be easier to just add submerged hydrofoils?

http://mysite.verizon.net/res6pe7p/index.htm

http://mysite.verizon.net/res6pe7p/HCSLAway4-03.jpg

http://www.******************/*************/Advanced_Hulls.htm

[bntii]

maybe this hull form would do the trick?

http://www.earthrace.net/view.asp?webpage=26

[Ike]

What you are describing sounds a lot like a SWATH. Small Waterplane Area Twin Hull. I know there have been quite a few ships built using this concept but I don't know if any small (under 100 feet) ones have been built. see http://www.solarnavigator.net/s_w_a_t_h.htm

[VT-tuna]

Swath technology is kind of what got me to thinking. My understanding of swath was that it basically was a set of submarine modules mounted to a cat hull with modules staying underwater. What I have read is remarkable for large boats with no info on smaller vessels.

Hydrofoil example above is interesting and actually saw that on the tube. Guy set it up wit pc control system (the real trick). But not very exciting as far as results with weight and speed with an outdrive in the water.

[VT-tuna]

Okay,
After reading a bit more and looking at the two hydrofoil links above, I feel foolish. Not an unusual feeling for me!


SO, why don't we see more hydrofoil boats. I have never seen one in person and based on the Talaria data (especially the low cost), seems like they would be more visible.

So here's some more questions (as I really like the hydrofoil idea now). Out drives simply disgust me in a saltwater enviroment. With speeds of more than 35kts, wouldn't the jet drive be the hot lick for this type of setup. I'm sure one of the biggest issues is pump intake but seems like that is very possible to deal with.

Any good links to provide some more specific data on hydrofoils. This will be a lot of fun to learn about. Thanks for the links already posted.

[stonebreaker]

Here's an interesting link. Scroll down to page 65 for advanced hull discussions.

http://www.dtic.mil/mctl/DSTL/Sec13.pdf

<EDIT> Here's one more: http://www.foils.org

[Ike]

Many of the larger hydrofoils do have jet drives. Boeing had a jet hydrofoil they called Little Squirt that they used to do a lot of research that was used when they built the navy hydrofoils. The problem is the technology is bit complex. But is more efficient than a prop. Hydrofoils are usually fast enough that prop cavitation becomes a real problem. But it is easier to use a long shaft outdrive than have a jet pump pickup in your foils.

[mark424x]

Okay,
After reading a bit more and looking at the two hydrofoil links above.

I'm not sure if you've run across the hysucat or other variations of the hydofoil supported cat. It's a passive system, so it's much simpler. They use a wing betweenthe cat hulls, and trim tabs in the back. You don't get completely free from bouncing in the waves, but there are boats out there with it already. It's been picking up steam the last 10 years, a local ferry in so cal that goes out to the islands is using the system.

http://www.allamericanmarine.com/cats/32_sportfisher.html
http://www.morrellimelvin.com/powerboats/cruising/022-Corsair.html
http://www.hydrospeed.co.za/index2.html
http://www.hysucat.net/cms/index.php?id=1
http://www.teknicraft.com/

[VT-tuna]

Guys, thanks so much for the info here. This started as a silly engineer trying to reinvent the wheel for a better ride to the fishing grounds. Been reading about this all day and just can't believe we don't see these hydrofoils designs here on the east coast (maybe I'm just not keeping the appropriate company). The foil assisted cat design seems to do exactly what I'm looking for and I don't have to invent it (which probably would never really happen anyway).

I will continue to look into this. Seems I can find a hull (35 - 40 foot) and retrofit the foils. Still don't like the outdrive thing but I have some silly ideas there too.

Thus far the only negative I have read on the foils is collision which to be honest is ALWAYS a serious issue even at 25 kts. Almost went in the drink myself 60 miles offshore once thanks to a mola-mola. The will be an exciting little adventure.
Thanks.

[mark424x]

Still don't like the outdrive thing but I have some silly ideas there too.


Let's here em, always like a good propulsion idea. Though I just sold my go fast boat and think I'll try to stay < 20 knots. Can't afford a boat big enough to go fast in the pacific rollers even with the foils.

If you are can use your top speed that's great, my old boat could do 55 and it was propped for that, I hardly ever got over 30, so it was very inefficient. Here an interesting tid bit you might like. I wish they made outdrives and outboards that could take much larger props and you could change the gear ratio.
http://www.ossapowerlite.com/tech_library/fuel_efficiency/fuel_efficiency.htm

[kach22i]

Not a stupid idea................just a little too late.:D

Link:
http://www.seaphantom.com/index.html

[VT-tuna]

Thats just funny (day late, dollar short). Actually, it has been remarkably entertaining to read all the stuff people are working on. Kinda funny in hind site. After graduating from engineering school and getting a brief insite into graduate school, I remember coming to a very sober realization that for just about any simple, silly, crazy or outlandish concept, you can be sure that atleast one individual now or past tense, has devoted near life time brain power to the thought.

[marshmat]

An issue to consider with SWATH is the problem of payload capacity. A large SWATH can take on ballast when running light and dump ballast when loaded, and an individual person doesn't change the attitude much. A 25-30' SWATH of comparable geometry to the biggies, would sink and rise far too much as people got on and off, or moved around- with so little waterplane it takes a large vertical motion to get a significant increase in buoyant force.

I think the hydrofoil concept is a good one for what's being discussed here. My concerns with foils are two-fold: the impact scenario mentioned above (hit mola, isocontainer, whatever and you're toast), and the cost. Also, to a lesser extent, the huge draught at idle speed. The draught problem can be overcome with retractable foils but that's expensive and trouble prone.

As for the foil/cat thing: Take a look at Prout's Panther 64 for ideas here. The thing is reportedly quite a pig in its natural form, slow to accelerate and cubmersome once on plane. So Prout added a big foil between the hulls up front, and three little foils in the back. The 70,000 lb Panther now does 45 knots with ease, carves like a runabout and draws only 1'6" while cruising, all on twin 1150 hp diesel/waterjet units.

[VT-tuna]

I'd like two please.

[kach22i]

I remember coming to a very sober realization that for just about any simple, silly, crazy or outlandish concept, you can be sure that atleast one individual now or past tense, has devoted near life time brain power to the thought.
You too?

I'm also born 50-100 years too late.:D

Now this was a ski machine, the Sea Dart.

http://www.aerospaceweb.org/question/performance/speed-record/sea-dart2.jpg

http://xplanes.free.fr/xf2/images/Sea%20Dart.jpg

[kach22i]

This outboard engine just ruins it for me.:(

http://www.seaphantom.com/trials.html
http://www.seaphantom.com/images/trials/large/prototype_leaving_bay_side_view.jpg

[marshmat]

Yeah, kach, looking at their site I think the production models, with inboard turbine power, will be somewhat more stylish craft than the Merc-powered prototype. It's a pretty neat concept, would love to see if it works.

[FranklinRatliff]

Okay,
After reading a bit more and looking at the two hydrofoil links above, I feel foolish. Not an unusual feeling for me!


SO, why don't we see more hydrofoil boats. I have never seen one in person and based on the Talaria data (especially the low cost), seems like they would be more visible.

So here's some more questions (as I really like the hydrofoil idea now). Out drives simply disgust me in a saltwater enviroment. With speeds of more than 35kts, wouldn't the jet drive be the hot lick for this type of setup. I'm sure one of the biggest issues is pump intake but seems like that is very possible to deal with.

Any good links to provide some more specific data on hydrofoils. This will be a lot of fun to learn about. Thanks for the links already posted.

www.foils.org

[FranklinRatliff]

You too?

I'm also born 50-100 years too late.:D

Now this was a ski machine, the Sea Dart.

http://www.aerospaceweb.org/question/performance/speed-record/sea-dart2.jpg

http://xplanes.free.fr/xf2/images/Sea%20Dart.jpg

Take off speed on the Sea Dart was about 120 knots.

[FranklinRatliff]

There are airboat props being made capable of handling 800 horsepower.

[Stephen Ditmore]

Have you seen Rick Loheed's boat? http://www.boatdesign.net/gallery/showphoto.php?photo=4877

If you encourage Rick I think he might have something to say on this subject...

[VT-tuna]

Yes, I think a link to his boat was posted in this thread. Absolutely love it. Looking over the site, their don't seem to be a lot of data of speeds. Not surprising. Anyone know what kind of speeds they have obtained yet. That boat would fit the bill about right.

[ABoatGuy]

One problem with a hydrofoil boat as a sport fish boat would be the foils (unless fully retractable) interfering with fishing gear in the water. It would be like fishing on a pier. For billfish, the boat also has to back.

[mariner 40]

buy a helicopter with pontoons

[SeaPhantom]

Hi VT-Tuna,
Not crazy at all. And no, it wasn't a SWATH you were describing, you said 'sub-hulls', not submereged hulls. After nine years hard labor, three in pure research, three years model building and testing, three years and three thousand hours plug building, mold making, parts construction, bonding, and rigging I just launched 'your' dream boat! (took three years just to write patents, sorry). Check it out @ www.seaphantom.com www.seaphantom.com

[SeaPhantom]

Hello Kach22i; fully agree. I had a turbine for an earlier two passenger model, but it was too small for the 34' five passenger model I ended up launching:mad: Couldn't afford a bigger turbine, so a friend lent me his race motor- can't argue with free!!!!:)

[FAST FRED]

Propellers working in air are capable of about 5lb of push for every HP.

The BEST that in theory can be done is 7lbs per hp (theoretical).

Most boats will get 20 lbs per hp , and better designs will get 25 with simple OTS parts (Off The Shelf) that are avilable most anywhere.

With ducts and fancier engineering some claim 35 lbs of push per hp.

Of course these "rulles" go out the window when using a prop when going fast enough for the water to be as hard as concrete. Surface drives have their own numbers.

FAST FRED

[VT-tuna]

SeaPhantom
Very cool that such a site as this can provide a response from guys like you that are actually doing it. Very cool indeed.

If you can mount some outriggers on that beast, I'd like a quote on the prototype. LOL. That thing looks awesome.

and eliminate the outboard of course....

[SeaPhantom]

Funny, my brother-in-law is a proffessional fish/yacht captain. He said if it floats' he can fish off it!! I actually had a request for a fish version- I'm thinking remotely piloted drones/for tuna 'tower', flip-out fish-fight decks w/safety lines, and pop-up fighting chairs!!! Unfortunately, for those of us with less cash than imagination, it'll start @ about$500k. But with the standard big fish machine regularly running over the $2mil range- maybe its not so crazy after-all??

[VT-tuna]

You are correct about the dollars. It really is a key reason I am beginning to explore the concepts. 500k doesn't buy much on the "NEW" sport fisherman market. I'm with your brother in law. If that things does cool stuff, I'd fish it in a new york second.

Oh, don't forget the blender and plasma. I like to watch the college football games when the fishing is slow. Go hokies.

[water addict]

If I remember right, a big problem with hydrofoils is dynamic stability and control. For example zipping out to the gulf stream takes you through choppy conditions, fluctuating angle of attack on foils, variable lift, oops, bow dips.....
ahhhhhh pitchpole at 70 knots!

[kach22i]

(took three years just to write patents, sorry).
You needed investors just to pay the patent lawyer fees I assume. Under six figures? Under seven?

I'm looking at all the spray being kicked up in those photos, from what I've been told not a good idea for Special Operations team delivery.

The guy I talked to about my own preliminary military hovercraft design four years ago said the RIB/outboard roostertails show up on radar letting everyone know you are coming - very bad.

They also like to use foul weather as cover, so a taste for heavy sea states (4?) are a must.

The part on the SeaPhantom website about injured/crushed spines and forced early retirement for Special Opps is a real concern, heard that first hand too.

Pitching and heaving is okay, shock and impact not so good, the SeaPhantom is very interesting in this regard - at least for me.

[kach22i]

Propellers working in air are capable of about 5lb of push for every HP.

The BEST that in theory can be done is 7lbs per hp (theoretical).

Most boats will get 20 lbs per hp , and better designs will get 25 with simple OTS parts (Off The Shelf) that are avilable most anywhere.

With ducts and fancier engineering some claim 35 lbs of push per hp.

Of course these "rulles" go out the window when using a prop when going fast enough for the water to be as hard as concrete. Surface drives have their own numbers.

FAST FRED

I love these boiled down rules of thumb.........keep them coming please.:)

[kach22i]

Surface drives have their own numbers.
............and they would be?

[SeaPhantom]

A second brother-in-law was a SEAL. Used to hang out on the Base @ Little Creek when I was in Boy Scouts. Saw body damage first hand. Most of the big spray in photos is from shots of high-speed bank turns (inboard foil dipped), or, just comming up on foils. Lots of spray then, but looks cool in photos. Once fully airborne, less than 16 square inches total in contact w/water. Not much there to make spray with (except prop). We'll be working with a military suspension contractor, whose background was Baja cars, to fit active suspension to maintain stability in nastier seas. The goal is 85knots over tops of six footers. (obviously outboard no longer adequite- going w surface drives and diesel turbine- no need for colling water pick-up))

Averaged six-to-nine hours working for someone else to buy each and every one of the more than 3000 hours it took to build. Plus several hundred$k cash. A Fortune500 analyst that came by my shop estimated the value spent was between $1.3 and $1.5 mil. But it was really just ten years of hundred hour work weeks.

[FAST FRED]

Originally Posted by FAST FRED
Surface drives have their own numbers.

............and they would be?

Sorry , I seldom remember stuff for boats I cant afford,

But another good rule of thumb is a gas engine will give 10 to 12 hp for every GPH

The old diesels (detroit 2 stroke or Ford Leman) will give 16 hp the 90's designs about 18 ,with turbos can get to 20 hp ,
and the electronic controlled ,dual wastegate turboed and INTERCOOLED diesels can get to 22 or so.

Untill the fuse blows, or the lightning strike.

Pick a diesel size that should run at 75% power 75% of the time, try for 90% power at 100% rpm, not "rated power".

If you frequently operate for long periods of time under 20% - 25% Rated hp you may have big troubble from underloading , wet stacking and excessive blowby from burnished cylinder bores.





FAST FRED

[kach22i]

If you frequently operate for long periods of time under 20% - 25% Rated hp you may have big troubble from underloading , wet stacking and excessive blowby from burnished cylinder bores.

I don't remember this important fact being covered in the diesel/elec hybrid drive system thread a couple of months ago.

How diesel-electric propulsion saves fuel
http://ossapowerlite.com/tech_library/fuel_efficiency/fuel_efficiency.htm

[kach22i]

Most of the big spray in photos is from shots of high-speed bank turns (inboard foil dipped), or, just comming up on foils. Lots of spray then, but looks cool in photos.

That is understandable, watching most hovercraft shows similar conditions and spary results although for different reasons.

The RIB's used in special opps can kick up spray because the craft may become airborn in tall waves causing the propeller to go in and out of the water at various angles of attack. Quite the show from what I've read, but I have no first hand experience on this I must admit.

100 hour weeks for ten years?

You need a vacation.:D

[FranklinRatliff]

Propellers working in air are capable of about 5lb of push for every HP.

The BEST that in theory can be done is 7lbs per hp (theoretical).

Most boats will get 20 lbs per hp , and better designs will get 25 with simple OTS parts (Off The Shelf) that are avilable most anywhere.

With ducts and fancier engineering some claim 35 lbs of push per hp.

Of course these "rulles" go out the window when using a prop when going fast enough for the water to be as hard as concrete. Surface drives have their own numbers.

FAST FRED

The best real world results for airboat props is about 4 lbs per horsepower.

Casey Baldwin, with support and financing from Alexander Graham Bell, set a water speed record of 70 mph with a hydrofoil boat driven through air screws.

[SeaPhantom]

100 hour weeks for ten years?

You need a vacation.:D[/QUOTE]

Thanks, really really tired now. Just launched five weekls ago, only need to sell one now. Have molds to reproduce. Did just get back from Bamahas:cool: - thanks to my amazing wife! Ended up scouting out potential operating sites. Lots of islands need fast transport. Sure hope.

[kach22i]

Thanks, really really tired now. Just launched five weekls ago, only need to sell one now. Have molds to reproduce. Did just get back from Bamahas:cool: - thanks to my amazing wife! Ended up scouting out potential operating sites. Lots of islands need fast transport. Sure hope.

Just put the old skull and crossbones on the vertical fin and you have the perfect pirate ship........................and of course the idea location will be close to your clients - the Bamahas or off the Ivory Coast.:)

http://www.imbetterthanyou.net/sparrow/pflag.gif

related thread:
http://boatdesign.net/forums/showthread.php?t=4049

[lazeyjack]

you know, I built a lot of alloy sportfishers
I started with wide chines, fairly shallow deadrise forward, in other words spoonish shaped entry, 17 degree deadrise aft and monohydran
After having the hell smacked out of me and the boat,(they were great downwind) I changed to very very steep deadrise forwards, sharp entry, I use one short strake forwards and the wide inbuilt chine
look at the desIgner DON SHEAD UK his very large motor yachts are like this
I found that I could power on over the roughest sea, landing was soft, stabilty downweather good I found that I could leave everything behind, the former config being down to disp. speed in the rough
Adding strakes just added to the hard ride, and gave nothing in return there is nothing to be gained in big vee aft, just makes the boat roll.
I would stick with this type of hull, odd things scare the hell outta of buyers when sale time comes around

[kach22i]

.............odd things scare the hell outta of buyers when sale time comes around
100% true, no argument from me.

However.........................as with the Sea Dart, some things keep coming around and around until the technology comes around and finally sticks.

Newer stuff:
http://www.vtplc.com/halmatic/product.asp?itemID=414&catid=92
http://www.vtplc.com/images/original/867.jpg
http://www.vtplc.com/images/original/868.jpg

And from the Anicient Greeks.............................

http://www.vroma.org/~abarker/olympmerch.jpg
http://www.megahobby.com/images/ZVD8514.jpg
http://web.mit.edu/mit-greece/www/page/trireme2.jpg
http://fauxtoys.com/tvag/pictures/alag-grhvy.trireme335w.jpg

............and as for ski's there is nature's models.

http://photos.jibble.org/albums/KennetandAvonCanal/duck_landing.jpg

[kach22i]

Although ducks when landing on ice can get hurt (no control), water landings are natural for them, something of a show though.

http://iversonduckcalls.typepad.com/iversonduckcalls/images/slipperylanding.jpg

[sub]

i think it ould work you just need to get past the fluid dinamics part, i my self am in the proses of building a craft that needs engines like the ones you are describing.

[marshmat]

Gotta admit, ducks really suck on anything solid.
I'm curious as to the design philosophy behind that little grey wavepiercer there. Very neat idea. Should be much nicer in big seas than a planing hull.
Love the SeaPhantom prototype there.... time to start saving my pennies and dimes :D Really needs the helicopter-style turbine, I think.... can't wait to see the performance numbers on the production version!

[brian eiland]

I'm curious as to the design philosophy behind that little grey wavepiercer there. Very neat idea. Should be much nicer in big seas than a planing hull.
However.........................as with the Sea Dart, some things keep coming around and around until the technology comes around and finally sticks.

You might have a look at these hull shapes as well;

Peter Payne's Seaknife
http://boatdesign.net/forums/showpost.php?p=81761&postcount=8

http://www.yachtforums.com/forums/16010-post47.html

Trimarans and the BladeRunner and BAT Air-Entrapment concepts
http://www.yachtforums.com/forums/general-yachting-discussion/2701-trimarans-bladerunner.html

[kach22i]

http://www.yachtforums.com/forums/16033-post49.html

Sea Knife:
1. Field of the Invention
The present invention is directed to a high speed boat 1 which does not slam or pound waves but cuts through them to ride smoothly at high speed even in rough seas.

That's really cool, but one would think sooner or later one would become airborn and come down hard cutting down deep in the water. I suppose this is why the Sea knife has a aircraft carrier type flanged top deck so it will not become a submarine.

Brian, do you know of anyother type craft besides RIB's and Hovercraft that prevent slam or pounding of waves using a soft material or inflated blatter/air spring/air cushion?

I'm thinking there are several alternate ways to deal with water/bow impact.

A: Slice it

B; Plane on it

C: Cushion it

D: Ride above it/fly

My perception and direction of goals regards hovercraft; which can cushion the blow of waves and in fair weather ride above the water surface. However as far as I know one has never really sliced the water with an ACV (Air Cushion vehicle).

[stonebreaker]

Doesn't really have anything to do with this thread, other than the talk about the turbine reminded me: http://www.nyethermodynamics.com/

Take a look at the vids for Squirt 2.

[brian eiland]

Doesn't really have anything to do with this thread, other than the talk about the turbine reminded me: http://www.nyethermodynamics.com/
How about this turbine powered RIB tender, http://www.yachtforums.com/forums/12004-post40.html (http://www.yachtforums.com/forums/12004-post40.html)