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," (http://www.lesliefield.com/other_history/speed_boat_developments_from_the_past_into_the_future.htm#) 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/modules.php?name=Products&op=fSearch&cat_id=&request=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,

http://www.clarkboats.com/2006-gallery/images/CB%20Pictures%20004.jpg

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]

GFBL = Go Fast Be Loud

Kelly:D


.....

[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]

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]

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?

[KCook]

Some of the faster cats don't bother with a full "V" on each hull. Instead each hull has a slanting flat bottom, angling upward toward the outside. So taken together the two hulls have the same effect as a "V". Step features can be tricky. Cat designs don't have the need for all the gimmicks found on some V-hulls. KISS rules.

Kelly

[stonebreaker]

Some of the faster cats don't bother with a full "V" on each hull. Instead each hull has a slanting flat bottom, angling upward toward the outside. So taken together the two hulls have the same effect as a "V". Step features can be tricky. Cat designs don't have the need for all the gimmicks found on some V-hulls. KISS rules.

Kelly
Have you ever heard of a Hickman Sea Sled? I came across a bunch of info here. (http://invertedvboats.bravepages.com/Other.html)

It appears to function somewhat differently from a modern tunnel hull in that it generates most of its lift from an inverted bow wave, instead of aerodynamic lift. What air it does trap under the hull is more of a friction reducer than a lift generator.

WINNINGHOFF BOATS..

We have now built 7 inverted Vee hulls, 36-50 feet, generally based on the "Hickman Sea Sleds" of pre World War I. Our experience with these hulls began in 1992 with a telephone inquiry for a nominally 44 foot boat which would have a top speed of 45 mph, carry 48,000 pounds, draft less than two feet loaded, and behave safely. After the idea of a hull "shaped like a brick" was rejected, we suggested trying an inverted Vee, a shape with which we had no prior experience. On the surface this idea had merit as the hull form is known to be fast and capable of carrying significant cargo, but it was unproven in recent time- at least in this size range and for such a rigorous application. The general concept of the inverted Vee is that the hull "swallows its bow wave" and rams air into the tunnel which thereby increases lift. We were fortunate to have Parker Marean, President of Woodin & Marean, Naval Architects work on the hull and structural design. Parker had available significant historic information on the Hickman designs and was able to draw up an improved version.

These hulls have been amazingly successful, providing speeds up to 50 knots, maneuverability and seakeeping. One of the 50 footers reportedly carries 70,000 pounds of cargo at 18 mph! We do not advise such operation, but 40,000 pounds at 30 mph is routine.

http://www.winninghoff.com/images/sled50.jpg
15m IV- 50' x 12', triple outboard (triple I/O)

http://www.winninghoff.com/images/sled352.jpg
10.7m IV- 35' x 10' (35' x 12') twin outboard

[Jimboat]

Stonebreaker - Yes, Morley Smith's articles are excellent! You will learn much from reading his material. I have worked with Morley over the years (I now have all of his personal research notes and archive files), as our development interests have always been quite similar. His thoroughness of research and understanding of planing hulls is one of the best in the world.

If you are interested in a power catamaran design, there are several articles on power catamaran design (http://www.aeromarineresearch.com/articles.html) available for download. Also check out "Secrets of Tunnel Boat Design" book (http://www.aeromarineresearch.com/stbd2.html).

The short answer to your original question re: "pontoon boat with planing hulls" is that, yes, the tunnel hulled design for such a boat is a very valid design.

[stonebreaker]

Jim,

Thanks for the link. I'm really facinated right now with the Hickman design. Do you have any articles on it? Or know where I could find some?

<EDIT> I'm wondering at what speed a true tunnel hull will begin to generate less drag than the Hickman hull. Since I'm not really targeting triple digit speeds (i.e., I can't afford that much speed), I'm wondering if pontoons in a long thin Hickman shape wouldn't be more efficient at 60 mph than a tunnel hull sponson. Since I also want to pull skiers, I'd like to know if the Hickman shape would get on plane faster, as well.

[Jimboat]

The Hickman design has very flat deadrise, and normally, has more wetted surface than a typical tunnel hull design....thus, acceleration to plane will normally be quicker with Hickman. Overall drag, however will be more in planing, due to exposed wetted surface area. Also, Hickman bottoms, due to very flat (zero deadrise), tend to have quite a rough ride in heavy waves. Tunnel sponsons can have increased deadrise to "soften wave impacts".

[stonebreaker]

The Hickman design has very flat deadrise, and normally, has more wetted surface than a typical tunnel hull design....thus, acceleration to plane will normmally be quicker with Hickman. Overall drag, however will be more in planing, due to exposed wetted surface area.
A trade-off! Who'd have thought an engineering solution would have a trade-off? :D

Question: Could I use your tunnel boat design software to analyze Hickman pontoons?

[Mike R. Cole]

Stonebreaker,

There appears no reason why a pontoon boat could not plan having the correct design. I saw you refereed to my father Dick Cole and his Cathedral Hull design.

[stonebreaker]

Stonebreaker,

There appears no reason why a pontoon boat could not plan having the correct design. I saw you refereed to my father Dick Cole and his Cathedral Hull design.
Yes, I was looking at something like the cathedral hull before I stumbled on the Hickman hull - Sort of progress in reverse. :p Actually, making two Hickman pontoons would be something like splitting a cathedral hull in half longitudinally, wouldn't it?

[yacht371]

I recently designed a planing pontoon boat for Smokercraft. At 22' it did 40 MPH on the first try with a 150 HP outboat. This is almost twice as fast as the cylindrical pontoon hull. This will be a production boat soon, with some features I can't tell you about yet.

It is pretty simple, just a pair of narrow deep-vee monohedrons, very simple but it works a treat. There is a special chine though, which I can't talk about yet and the construction methods are new.

[stonebreaker]

I recently designed a planing pontoon boat for Smokercraft. At 22' it did 40 MPH on the first try with a 150 HP outboat. This is almost twice as fast as the cylindrical pontoon hull. This will be a production boat soon, with some features I can't tell you about yet.

It is pretty simple, just a pair of narrow deep-vee monohedrons, very simple but it works a treat. There is a special chine though, which I can't talk about yet and the construction methods are new.
http://www.clarkboats.com/

http://www.clarkboats.com/2006-gallery/imagepages/image18.html

[yacht371]

The Clark "Performance Pontoon Boats" are indeed similar to the boats I did for Smokercraft, and I imagine the performance is similar too. Our innovations are primarily in the area of construction methods.

[stonebreaker]

The Clark "Performance Pontoon Boats" are indeed similar to the boats I did for Smokercraft, and I imagine the performance is similar too. Our innovations are primarily in the area of construction methods.
Great, maybe you can give me some pointers then. Both Clark and Tracker make their boats from .125" 5052 aluminum. I would assume they have good reasons for choosing this alloy, but I haven't been able to find what filler metal to use when welding it.

[yacht371]

That thickness and alloy is pretty standard for these boats. I'm not a welding expert.

Our construction methods do not use welding or rivetting. Also, I'm a Naval Architect, not a builder. I tell builders what shape to make the boat, but in general, they figure out how to build it. Sorry!

[stonebreaker]

OK, I have a question on planing hull shape. What part of the hull makes a planing hull bank into the turn like an airplane? I'm assuming that as the boat turns, the vector of the water in relation to the bow changes, such that as you make say, a turn to port, the hull slips a little so that the apparent vector of the water in relation to the boat comes in from the starboard bow instead of head on? And the lift is then generated by the angle of the hull bottom to the water moving past it?

I can picture this easily on a v-bottom, but have trouble with something like a cathedral hull or even a flat bottom. In the case here, I'm considering using a Hickman inverted vee hull, and I don't really understand how that shape would generate the banking lift to turn, either.

[marshmat]

With prop-driven planing monohulls, part of this 'banking' motion in turns comes from having the thrust on an axis considerably lower than the boat's CG and CB; turning to port will cause that thrust to push the stern to starboard and will also roll the boat counterclockwise as viewed from astern. With jetboats that have their nozzles pointed perfectly parallel to the direction of travel, there's considerably less banking than on a prop-driven boat (most jets angle down a bit though). So the turning of either the drive or rudder contributes to the banking motion; Stonebreaker, you seem to have the right idea as far as the rest of it (the hydrodynamic part) goes but I don't think I can clarify it much without pictures. Once the hull begins to bank, of course, the effective deadrise is higher on the outboard side and lower on the inboard... it is of course a pretty complicated motion to analyze and I'm afraid I can't explain it too well here.
You might notice that with cat and pontoon hullforms, the boat usually stays pretty much level in turns. With asymmetrical hulls it is possible to make a cat bank like a deep-V (a la Benchmark 38) but most cats have very high initial stability and won't carve into turns like V-hulls do.

[stonebreaker]

As long as it stays level, I'm cool. I just don't want to dig in the outer sponson and roll the boat, that's all. I'd rather figure out some way to add some lift to the outer pontoon so that in a worst-case scenario the boat would spin out, not flip.

[marshmat]

If I recall correctly (someone make note if I'm wrong), Benchmark gets lift on the outboard hull in a turn, by making the outer deadrise of each hull steeper than the inner deadrise. The hull bottom facing the ocean might be 29 degrees; facing the hull tunnel, it might be 22. Thus when the boat turns, the outboard hull tends to push upward more than the inboard hull. These are fairly typical V-bottom hulls, just with asymmetrical deadrise.

[War Whoop]

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,

http://www.clarkboats.com/2006-gallery/images/CB%20Pictures%20004.jpg

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

Now that is way cool !

[kagraham]

i would recomend just buying or taking ideas from these guys, http://www.playcraftboats.com/ they seem to have the right idea. I saw some similar with modified V8 I/O motors on tablerock lake in Missouri. I cant find a website for those though..

[stonebreaker]

Nah, that's just another 'toon with lifting strakes attached to standard pontoons. Great solution so far as cost-effectiveness, but like Manitou, they have to add that third pontoon for some reason - I assume the lifting strakes either just don't generate enough lift to work with only two pontoons, or they can't be made large enough for structural/strength reasons on only two pontoons.

[DTVM]

I have a strong interest in your idea about the hickman pontoon system. Have you gone any further with you idea?

[stonebreaker]

Haven't gotten past the model stage so far, due to lack of funds. However, I'm planning on picking up a tig welder with the tax return and then I can get serious. I'm also wondering if any of the free/cheap design programs could produce a set of shapes that I could give to a sheet metal shop to cut out of aluminum sheet, or if I'll have to build a full scale model with cardboard or something and give the cardboard shapes to the machine shop.

[skypoke]

Hang on, Stonebreaker, you don't really want a tig machine, you need to use MIG. The 5052 alloy you spec will work though it's a bit malleable and you would most likely use 5083 or 5085 for more strength and corrosion resistance. But for a recreational duty boat the 5052 will save you lots of money on material and be just fine. Wire for mig filler will be 5356, works with any of these alloys.

Why not TIG? Well, granted it does produce a pretty bead though the new MIG machines can pretty well achieve this too. Problem with tig is it's very slow and heat generated is enormous...because you're going slow and adding filler by hand. With mig you will be running bead really fast though even with this process you will be battling heat. Heat equals distortion and it's the single largest challenge you will face in building. Even though you can lay down several feet of mig bead a minute, you will only be running beads a max of 4-6 inches long at a time. Any more than this and you will have a warped mes on your hands. I'd suggest your first investment be in a book called "Boatbuilding with Aluminum" by Steven Pollard. It's in print, available anywhere, relatively cheap, and the bible as far as I'm concerned. We just finished a 28' alloy pilothouse powercat so have some experience in this. Sounds like a great project!

By the way, if I was building such a simple hull form I wouldn't mess with having your material plasma cut...it's relatively expensive, takes a lot of cad work to generate the files, and most cut services won't have much interest in this small project. A good carbide blade on a skilsaw will easily cut these simple shapes. It's not hard to template plates over your frames and each template will most likely work for 4 hull plates in yer cat. Good luck and let me know if I can help.

Chuck

[stonebreaker]

Thanks for the tips, especially the one about the skil saw. I appreciate the tip about the tig welder too. I'll keep an eye out for a machine that will accept a spool gun.

[stonebreaker]

BTW, I ordered that Pollard book you recommended. Any other reading suggestions would be appreciated. I'd like to find some guidelines on construction - calculating hull thickness, framing, all that stuff. My problem won't be making things too weak - quite the opposite. I tend to over-engineer, which makes things safe, but slow.