pontoon boat with planing hulls?

[stonebreaker]

Is this possible? I've been reading up on the site, including Morley Smith's "Speed Boat Developments From The Past Into The Future," and I haven't found anything similar to what I'm looking for.

My wife and I are considering buying a boat, and a typical 22'-24' party barge with aluminnum pontoons seems like it would meet about 80% of our needs. Well, actually, it would meet 100% of OUR needs. But, it's hard for me to leave something stock. I've been hotrodding cars for about 10 years now, and it's fun as heck to drive around in a sleeper caprice 4 door sedan that looks like grandpa's car but runs 11.5 at 120 mph at the dragstrip. (I still get 22 mpg on the highway, too.)

So, I got the idea to hotrod the pontoon boat. The pontoon boat is very appealing to me as a hotrod project because I love sleepers. (sleeper: a fast vehicle intentionally designed to create a false impression of being slow.) I had initially thought to make it a hydrofoil (always wanted one of those), but after reading about how vulnerable the foils are to objects in the water, I gave up on that idea, due to the local lake (Carlyle Lake, Illinois, USA) being created over a forest. About a third of the lake is flooded standing timber. Plus, the foils would definitely interfere with beaching the boat and also fishing in shallow water.

In the course of my web surfing, I came across a picture of a float plane. Putting airplane floats in place of the pontoons seemed like a good idea initially, as I'm barely able to balance my checkbook, nevermind design a boat hull; but Mr. Smith's paper convinced me that slapping a couple of old airplane floats on the boat probably wouldn't work all that well, even if I could locate some near St Louis.

Now I'm looking at putting some type of planing hull on the boat. Currently, in keeping with the sleeper theme, I'm wondering how effective two long, narrow planing hulls would work in place of the round pontoons. Something like a sponson on a three point hydroplane, only running the full length of the boat. Each hull would be 18-22 inches wide and about 24 feet long. The long narrow shape would also help keep the boat efficient when moving slowly in displacement mode.

Design speed would be somewhere in the 60 mph range.

Any help or pointers to good books on planing hull and/or power catamaran design would be greatly appreciated. Hull material is most likely going to be aluminum, since I already know how to weld aluminum, so any help you might have in how to decide how thick the hull skin needs to be, as well as bulkhead placement and other internal bracing needs, would also be gratefully accepted.

And yes, I could go down to the local marina and just buy a deck boat. But where's the fun in that?

[KCook]

You could buy one ready-made:

http://www.clarkboats.com/

But it's the tri-toons with wide lifting strakes that are the popular solution for performance 'toons:

http://www.manitouboats.com/main/mod...partnum&boat=6

In any event you will need a whole bunch of power to ever see 60mph.

Kelly Cook

[stonebreaker]

Kelly,

Thanks for the links.

The Clark boats are pretty much exactly what I had in mind, but there's not a lot of info on their website. If you know where I can find out more about them, I'd be grateful. Meanwhile, I'll be surfing the net. The Manitou guys seem to have struck a nice compromise between performance and comfort - the larger center pontoon that allows the boat to bank into a turn instead of turning flat, is a great idea for handling comfort. It helps that there's a local boat dealer that carries them, too.

Of course, being the stubborn damnfool gearhead that I am, now that I know this idea is not only possible but practical, I'm even more determined to build my own boat that's faster and lighter than either of those two. The Manitou system, in particular, to my untrained eye, anyway, appears to have sacrificed a great deal of speed for handling comfort by putting in the central pontoon. This seems like a good solution for a commercial venture. Actually, it seems like an excellent solution from a sales viewpoint because it delivers a very good compromise between speed and handling in a very cost-effective manner.

The Clark boat seems like less of a compromise. I guess I'll have to contact them to get some sort of price list. Still, judging by this picture,



They appear to be using a very simple design that doesn't require a lot of fabrication or custom materials, just aluminum sheet and a simple extrusion. Does this appear to be an efficient shape? Is there some other hull design that, perhaps for reasons of labor cost, they're not using but would provide a performance increase? Dick Cole's cathedral hull, for example, or perhaps a stepped hull? I have an advantage here because I will be getting my labor for free. What I need is help picking a design and/or some pointers towards planing hull design books and software.

Thanks in advance for your help.

Randall Stone

[KCook]

For shear speed I would just copy one of the fiberglass cat designs, but in aluminum instead of 'glas. Both Kayot and VIP have (or had) cat deckboats that would run near 60. Best known small GFBL type cat would be Eliminator Daytona, which will run well over 70. If you look at the bottom on an Eliminator cat it is simpler than some of these slower boats.

Kelly

[stonebreaker]

Kelly,

Thanks again. What does GFBL stand for?

[KCook]

GFBL = Go Fast Be Loud

High performance models such as Cigarette, Eliminator, Fountain, Skater, etc. Typically have open exhaust, thus the "Be Loud" part. Very much "in your face" boats, the opposite of a "sleeper".

Kelly

[stonebreaker]

Originally Posted by KCook

GFBL = Go Fast Be Loud

Kelly

.....

[DesioMedia]

Rember to make the deck area very strong and preferable aerodynamic. We dont want coutches flying off at 60mph. In addition I would not use the classic plankwood tyed to the pontoons but rather a cat type hull where the hull is build in to the pontoons as one piece.

Good luck friend.

[stonebreaker]

Originally Posted by DesioMedia

Rember to make the deck area very strong and preferable aerodynamic. We dont want coutches flying off at 60mph. In addition I would not use the classic plankwood tyed to the pontoons but rather a cat type hull where the hull is build in to the pontoons as one piece.

Good luck friend.

To be perfectly honest, I'm not sure I have the design skills to build an air-entrapment hull. Nor in my skill as a driver - I've seen those things blow over on ESPN. I'm thinking more along the lines of some type of hull that creates a boundary layer of bubbles - sort of like those total-body swimsuits they wore in the last Olympics.

[KCook]

So far as I know blow-over is rare with 'toons. For air entrapment to have real effect you need a tunnel with a lower ceiling than seen on 'toons. But the air pack will help the fast 'toons loft their bow some. Looks odd as heck compared to how normal 'toons run.

Kelly

[waikikin]

How about a bimini shade wing - for lift, with a sleeper ruffle around de edge, maybe a tail spoiler to keep the props glued in, mounted on top of the wc compartment, sub waterline exhaust for slow running & when u open her up the lift brings em clear of the sea & your off at full noise - I think I need one too! Regards from Jeff.

[marshmat]

Stonebreaker- the photo you posted earlier is indeed a fairly simple hull design; it has to be, since aluminum doesn't like compound curves. But it's also a very good compromise- flat enough to plane, sharp chines (good for planing), but also a fairly sharp V entry and narrow bow, which will make it comfortable in chop and allow reasonably efficient cargo-carrying at low speeds. This is close to an ideal hull form for a planing pontoon boat.

[Go Cat Go]

Take a look at the cat at MTX.com.

[Go Cat Go]

Sorry that is MTXmarine.com

[stonebreaker]

Originally Posted by marshmat

Stonebreaker- the photo you posted earlier is indeed a fairly simple hull design; it has to be, since aluminum doesn't like compound curves. But it's also a very good compromise- flat enough to plane, sharp chines (good for planing), but also a fairly sharp V entry and narrow bow, which will make it comfortable in chop and allow reasonably efficient cargo-carrying at low speeds. This is close to an ideal hull form for a planing pontoon boat.

What kind of mods could you do to decrease drag? I've seen hulls with steps in them - I'm guessing the steps help introduce air under the hull? (I'm researching as fast as I can to cure my ignorance!) What about texturing the hull to create a bubble boundary layer, the way those radical swimsuits do for the olympic swimmers? Don't they do that for some military ships?