Quad toon Question

Discussion in 'Boat Design' started by luckyjr, Sep 14, 2011.

  1. luckyjr
    Joined: Aug 2011
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    luckyjr Junior Member

    I have just put a light weight steel floor and cabin on my Crest 28' and It is working very well. Now I would like to design and build a Quad toon because on the lift created between the two pontoons 00--00 . This is not a big problem for me, I owned a ASME fab plant. I can get Aluminum 5' x 12' .091
    for $180 + $85 for rolling. Couple of hours to welding the long seam and I have a 19" dia. toon front section ready for the nose and rolled angle stiffners. 1/8" plate for the rear part of the toon, 00--00. The way I see it is, each side would have 38" of surface with a natural flow channel between them. What are the pros and cons comparing them to a 25" standard toons? Thanks
     
  2. Village_Idiot
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    Village_Idiot Senior Member

    Why not go with a couple square (rectangular) pontoons, maybe 42 inches wide and 18 inches high? Will double your welding, but you'll get better floatation, better lift, better reserve buoyancy, better CoG plus all the benefits of pontoons. The big mfrs. don't use them because they cost more in high production, but would be ideal for your fabrication setup.

    It will be more work, but would be a good idea to weld in cross plates to make separate floatation chambers within the pontoons (but then you are using pretty thin aluminum to begin with, will be difficult to do much welding...).
     
  3. luckyjr
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    luckyjr Junior Member

    Thanks for your views,
    Wouldn't the turning radius and skidding be effected at higher speeds? I plan on a 300hp. Your right labor would eat you up. It takes about 20 min to roll the 19" Can 12' long and 3 hours to weld one 12' seam plus closing the ends 5'. This welding can be done with a turning roll and auto welding.
    You want to elimate any possibilty of holes in the welds. The more welds the greater the possibilty.

    0_0 , I was thinkg about putting a upside down T between the pair to join them. How far down should the T go down and how wide to create more lift?
    Maybe not, the channel on the bottom maybe enough. 00
     
  4. messabout
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    messabout Senior Member

    You will skid less with a rectangular section than with a round section. Since you intend to use a lot of power (300HP ?), you must intend to have a bat out of hell go fast boat. The flat sections will go faster for a given power input by a signifigant margin. The very reason for commercial pontoon boat builders to use round sections is exactly the reasons you have stated. Cheaper!, not better.

    Fuel economy will also be better with rectangular sections if you go at a fast speed, pull skiers, or load the boat heavily. Round sections might show a slightly better fuel consumption figure only when you are moving at idle speed. The flat sections will also draw less water for a given load and thus be easier to launch and retrieve.
     
  5. luckyjr
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    luckyjr Junior Member

    Thanks good info,

    What about this , Alum flat on the bottom, then break a 45 angle on both side, then back to 90 angle \____/ ? Turn it over and lay bent section on top of flat alum plate to weld closing seams. Should it have a lip to knock down spray? -\____/- Thanks
     
  6. claydog
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    claydog Junior Member

  7. luckyjr
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    luckyjr Junior Member

    Sold, the premier is what I was getting at in my last post. So, 42" x 18" with a angle 45 or 60 on the bottom 2 coners. .091 Alum in front 12' and .125 in back 12'. 4 chambers stiffners each 6 foot. Gives me 7' of pontoons, is 18" wide enough for the motor and transom? http://forums.iboats.com/attachment.php?attachmentid=106440&d=1312513608 This the floor i am using, I think I will go with Alum risers and galv steel cross members.
     
  8. Village_Idiot
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    Village_Idiot Senior Member

    Also check out Clark's performance pontoons - he makes a pretty good custom boat at a reasonable price: www.clarkboats.com
     
  9. Easy Rider
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    Easy Rider Senior Member

    luckyjr,
    Do you mean to arrange your "quad" pontoons like OO--OO. That would increase wetted surface a lot and cause much "interference" drag ...to put it in aviation terms. I think the Premier toons are excellent but one would get higher freeboard w single toons of the same volume with less aluminum. So I think the quads would increase drag and the Premier wide toons would dramatically increase carrying capacity. Your post #5 looks good to me.
     
  10. Wavewacker
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    Wavewacker Senior Member

    I'm in pontoon country, worlds leading manufactures within 50 miles in several directions. I would think that if OO----OO were more efficient than larger U-----U, they would make them that way. The V toons are the way to go IMO, as mentioned above. The tri toons are really 2 1/2 toons in many cases as the middle doesn't go all the way back as the sides do.

    There is also a pretty efficient foil system available for toons to provide better performance, I hear they work well.

    At least in my area, there is not much difference in price of having "standard" custom fabricated toons purchased than fabricating your own if you are having the work done.
     
  11. messabout
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    messabout Senior Member

    Easy Rider is as practical and correct as usual. Two pontoons will be less work, less material, and less wetted surface, while probably providing better straight line performance.

    Start a design like yours with a list of requirements (LOR). Describe exactly what you want the boat to do, the accomodations, the materials, the accessories and conveniences, and the method of powering the boat (outboard, inboard, IO, etc.) Make a realistic set of calculations of the total loaded weight including passengers engine, fuel, water, and whatever else there may be. Only then can we make educated decisions about the size and section configurations of the pontoons.

    The Trimaran boat in the video is pretty interesting. The designer has made the center hull the main load carrier and let the outer hulls provide stability in turns or when 9 unseamanlike passengers run to one side of the boat to ogle the bikini girls on the beach.

    In my first post I accused the conventional round pontoons of being the result of economy considerations. That was not the whole story though. A round or curved section has more skin stiffness than a flat rectangular section. The flat running surfaces will need a lot more internal stiffening than the round ones. Without the internal stiffeners the flat plate will tend to scallop under load. If that is not sufficiently compensated the result will be diminished performance. The hulls will have a series of "hooks" that are most unwelcome in a planeing planform. You can live with athwartships plate deflection but not fore and aft deflections. The tri in the video is seen to have a series of brakes in the main hull. That stiffens the areas of interest. Clever.

    Your prospective materials are 3/32 and 1/8 thickness. The 1/8 plate will be on the order of 2.4 times stiffer than the thinner plate. All that needs to be taken into account when you are doing the design work. Stiffness is loosely a function of the third power of thickness but the deflection of the unsupported span of the plate is a function of the fourth power of length or breadth or a complex combination of L and B.

    Don't let all that academic jazz deter you. Just build the boat but do some careful planning and research before you cut the first piece of material.
     
  12. luckyjr
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    luckyjr Junior Member

    Thanks for help, nice to see a forum where egos aren't king.

    [​IMG]

    This is what i came up with after talking to you'll, 40 dia with strakes broke on the side. Those points will be the connection weld location.
    I have a plant down from mine, They have a 40' break, and do electrical towers. They use octagon breaks for their poles. Wonder what that would look and perform like. lol Thank again for the advise everyone. I did give Clark a call to how much they would do this design for. We are playing phone tag. I am looking for a shallow running boat for the bays. May no put a fence
    on it. Holds a lot of fisherman. Once we get to the fishing hole, everyone gets out and wades anyway.
     
  13. luckyjr
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    luckyjr Junior Member

    Styrofoam in pontoon

    I obtained prices for 10' section of 20" dia. 1/8" 5052 pontoons formed with the flat sections on the bottom and side. All ends and long seams welded. $850.
    I have deceided to go with a 28" x 20" rectang pontoon in the middle.

    I will have 2 rounding rings inside ea section and will insert a 19 x 19 $66 block of styrofoam 10' long inside the hybrid round sections. The rectan pontoon will have a 28 x 20 styrofoam block 10' long in each section.

    How unsinkable do you think this design be and what do you think of the pricing. Thanks
     
  14. Kipp
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    Kipp Junior Member

    100 mph Playcraft Boats

    I would suggest you go to this site...If you are considering building a pontoon...they hold the 2011 shootout record 103 mph and considered the best builders of pontoons..in the industry.The videos can be seen on You Tube..just type in the Title above..Another Place to look at their pontoons is at "Performance pontoons & Deckboats it will give you a good look at the performance line..for high speed/lift/control.
     

  15. luckyjr
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    luckyjr Junior Member

    b.jpg

    Thanks for the info. More of a modified center console pontoon.
     
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