4ft Sailboat Mini PDR Racer

Discussion in 'Boat Design' started by Micro, Oct 25, 2011.

  1. Micro
    Joined: Oct 2008
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    Micro Junior Member

    Hi all,

    Just throwing the idea out there of a mini PDR Racer style sailboat around a box rule, Max 4' long, 4' wide, 2' from bottom to highest freeboard and 2' keel from waterline.
    What are your thoughts?
     
  2. rwatson
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    rwatson Senior Member

    They seem to have a lot of fun - OK or kids, but waaaay to small for us big guys
     
  3. tom28571
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    tom28571 Senior Member

    There are many formulas for having fun and the PDR seems to be one of them. Often lost in the discussion is whether the PDR is a good boat. 8' is minimal for an adult even with the best designs. The PDR group coined a term "pig rooting" to describe some sailing behavior. Whatever that means, a 4' model would be much better at it.
     
  4. lewisboats
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    lewisboats Obsessed Member

    Don't see how it would work...you need room for you, the mast, the sail, the lines the tiller, and something to move it when the air disappears. I tried with a 5.5' boat and gave up on the sail part...there just isn't enough room. Directional stability would be another issue, along with a best speed of about 1 kt. If you want to row it it might work but I expect you would just be bobbing around most of the time.
     
  5. pistnbroke
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    pistnbroke I try

  6. Micro
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    Micro Junior Member

    If you sit in the bottom with your back against the transom with rope or pedal steering. Mast and centreboard between your legs.
     
  7. lewisboats
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    lewisboats Obsessed Member


    Well with your weight that far back you'll look something like this:......you'll also have to have a very high aspect ratio sail to get any area at all or else you will have to swallow your daggerboard to get it near the right place. The mast would have to be bolted to the forward transom, you would still have very little directional stability and you would very likely flip over backwards as even a small wake wave catches you under the bow transom.

    edited to add: Oh...and that mast will have to be raked forward about 10 degrees just to be vertical enough to be useable (the boat is rotated 12 degrees) so you better bolt it to the outside and put a block to angle it properly. You will probably need about 12 ft of mast (2 ft bury, 2 ft bare mast for head clearance and 8 ft of luff. With a 4 ft foot this will come out to 16 sf of sail...and blow you right over with the leverage. Oh..and max hull speed will run to about .75 kt because of the shortened waterline. Nope...you won't be doing any planing either.
     

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    Last edited: Oct 26, 2011
  8. lewisboats
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    lewisboats Obsessed Member

    Here ya go with sail.

    [​IMG]
     
    Last edited: Oct 26, 2011
  9. messabout
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    messabout Senior Member

    Aha! A boat built for leprechauns.
     
  10. upchurchmr
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    upchurchmr Senior Member

    Do it please. Take a video to the launching, pay up your insurance. Maybe you can get money from Funniest Home videos to get a real boat.

    Basically if you just go ahead and do it you will probably be too embarassed to post the results. But I really suggest the old classic - the antique cast iorn tub. It will sail better.
     
  11. Micro
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    Micro Junior Member

    No theres an idea! Bathtub racing!!!
     
  12. Tiny Turnip
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    Tiny Turnip Senior Member

    Last edited: Nov 2, 2011
  13. lewisboats
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    lewisboats Obsessed Member

    Don't see the possibility of a sail there either.
     
  14. sharpii2
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    sharpii2 Senior Member

    I don't see the practical value of such a concept.

    If I'm going to go to trouble of building a boat, I might as well build something useful.

    In the case of puddle duck racers (I prefer to call them puddle ducks), you have an excellent boat for small bodies of water. Not only that, but because it has such high initial stability, it is an excellent sailing training vessel. It may someday become as common as the 'sunfish' and 'snark' types. There are already at least three designs in this class drawn by professional designers.

    The problem with a severely chopped version is that it is not all that useful, due to its lack carrying capacity. It would also be quite unsafe for anything other novelty use in warm, calm weather, very close to shore. It would row at less than 2 mph and would hobby horse so much that it may end up being even slower.

    I have considered the idea of making a much longer and deeper rockered straight sided scow and starting a new class based on it. I would then have an opportunity to legislate around some of the flaws in the pdracer class rules.

    The two main being that the hull shape is too tightly restricted and the sail area to displacement ratio is not restricted enough. A light boat with a light skipper is allowed to race with a heavy boat and reduced rig on an even basis.

    I have seen this flaw since the beginning of the class, when a large rig was around 60 sf. Now there are boats in the class that weigh less than 60 lbs, have light skippers, and sport rigs up to 100 sf (believe it or not, the hulls are more than capable of carrying such large rigs)

    My new class will have a fairly simple formula to calculate the allowable sail area. It will be sloped to favor heavier boats slightly. The reasoning is that in a lighter wind day, the heavier boats will have a slight advantage and with a stronger wind, the lighter boats will have an advantage. No fun having the same boat win race after race, because of an inherent advantage.

    The longer, deeper rockered boat will not have the initial stability of the shorter wider pdracer, but will be able to heel more before the lee transom corner digs in. It will also be long enough to lay down in and have storage compartments at each end. It will not be intended to replace the venerable pdracer, but to supplement it.

    It will have better upwind capabilities in choppy waters at the expense of being heavier and slower for its length, due to less ail carrying capacity. It would be a more raid capable boat.

    As you see, like the pdracer, it will have an actual use, rather than being just a novelty.
     

  15. upchurchmr
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    upchurchmr Senior Member

    Tiny Turnip,

    You would still be better off with a bathtub. That guy can't even stretch out his legs to brace a stroke. If he finished a stroke the slightest mistake would submerge the bow and fill up the boat. Could he even carry a 6-pack?

    sharpii2,

    If you put lipstick on a pig it is still a pig. OOPS, I was going to be nicer. Lets just say that if you built a boat that actually functions as a boat and didn't look like my 4th grade sandbox you could enjoy the boat more.

    I am not a fan of Bolger flat slab boats but Bolger put out some nice simple boats - like Gypsy - 5 sheets of 1/4 inch ply
    http://www.instantboats.com/gypsy.htm

    The PDR claims 3 sheets of ply, to me 2 extra sheets is virtually the same for a much better boat.

    I expect you could make a PDR clone by taking the "foundation" of your full size bed and turn it upside down as the hull. It would save you the cost of most of the plywood.
     
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