small performance sailing dingy plans

Discussion in 'Boat Design' started by d_sinsley, Jun 28, 2007.

  1. d_sinsley
    Joined: Jun 2007
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    d_sinsley Junior Member

    I want to build a boat. Can't get the idea out of my head. My mind has wandered from a 25 ft trailerable to a little minicup once published in popular mechanics. All came up leaving me wanting. Here is what I want to do.

    I want a boat that will fit in the back of a pickup truck. Lets say under 10 feet no wider than 5 feet. Needs to be light. It needs to be able to be sailed to it's capabilities by one with room for two. I am a performance freak. I would like it to have no aft stay or runners just swept shrowds so I can run a big full roach main, a non-overlapping jib, retrachtable sprit for asymetrical spinniker. Some ideas I have had are a tunnel for spinniker like a 505 has, and an open transom. Boats I like, the viper, international 14, 49er, and melges 24, all have the look and ideas i'm after.

    Another idea would be to add a lifting keel with nice high aspect ratio and a bulb and then stick it on a trailer

    This will be a do it yourself project. Building materials could be anything, wood, fiberglass, even thought once about carbon fiber (cost may kill this idea). I am not opposed to learning to make a mold. Or use alternate methods of lay-up such as strechting mesh over stringers and laying it up from the inside out.

    This project will be more about the building than the end result. I know how to sail I want to know how to build a boat. Thats the idea.

    Is there a question in all of this, yes. Is there a design already out there that would satisfy my all or most of my needs? and if not what would it take to commision a design like this? If I get nothing more than a set of paper dreams then that would be ok as long as they are my dreams. this would not be an AC Team budget, but rather a few buddies and a six pack of beer budget.

    Any help anyone? Just think we could put our name in Sail magazine "... the 2012 boat of the year, a ****** and Sinsley design"

    Dreams!!
    Devon
     
  2. alan white
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    alan white Senior Member

    of course there are many designs already out there, and you are as qualified to read about their attributes as anyone.
    Your favorire modifications to that existing design would definately be a good subject for discussion here. Many good designs could stand far greater sail areas (and earlier/faster planing) if modified with a canting keel on a deep foil.
    Since a dinghy hull is generally meant to be sailed upright, the hull should change little with a canting bulb keel (a straight ballasted keel/ballast would not be effective until heeled, so the hull itself would in that case want to be designed to sail at greater angles of heel). Rather, use a canting keel with some extreme depth and muscle it over manually, and stay vertical.
    This opens your options up to include any planing dinghy in the size range, though compensation for the ballast weight would require a bit more boat underwater (say, 2 1/2 cu. ft), and there are people here who could suggest ways to add that displacement into the shape, perhaps by such as something as simple as widening the hull a couple of inches.

    Alan
     
  3. PI Design
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    PI Design Senior Member

    Less than 10ft?
     
  4. alan white
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    alan white Senior Member

    Hopefully 12-14 ft. Long as you gotta trailer anyway...
     
  5. d_sinsley
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    d_sinsley Junior Member

    the 10 ft is really an number off my head. light and portable in the bed of a pick-up truck (cartop) was the idea there. If it takes on a heavy keel it could well be longer due to the fact it will end up on a trailer. The main idea is something easly rigged and launched by one in a few minutes, read: less time rigging more time sailing.

    The canting keel idea is a great one. Since we are really not talking about a big boat I would think this would be easly managed with the proper purchase by one. I can see where this would lend itself to a flater hull design like a skiff. Would the weight negativley effect the plaining ability in light to medium air, thereby defeating the purpose of a plaining hull or would the increased sail area overcome the weight and put the boat on plain.

    Devon
     
  6. d_sinsley
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    d_sinsley Junior Member

    witht the ballasted keel it would trailered. That is of little issue a small trailorable would be fine.
     
  7. alan white
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    alan white Senior Member

    A canting keel need not be so heavy----- maybe 150#, maybe 5 ft draft. The idea is to plane sooner rather than later. A crew member hiked out would do the same as the keel, but the keel allows you to carry a lot of sail alone, and so you are getting more horsepower with the bigger sailplan.
    This would be a rather dynamic ride. The light hull will react fast, and so must you.
    I would say you might get away with a sailplan of 140, which is extreme for a +/- 12 footer. The canting keel is an engineering trick, so the entire rig might be designed in a box that can be raised by a halyard at the ramp using a purchase of at least 2:1. What's left in the boat is a rectangular hole and a view to the water. Much like a plug used to cover a hole for an outboard mounted inboard, except a bit more complicated.
    What you cannot do is raise the keel to run downwind.
    Nor can I figure out how you will supply the power to shift the ballast, though spilling the wind and shoving your weight to the windward side down to the gunwale with the keel released would work--- pumping the boat itself, which just might work in a small boat.
    You wanted adrenalin, right?
     
  8. Doug Lord

    Doug Lord Guest

    Performance Dinghy

    Do a search for some of the perfomance dinghy threads in the "Sailboats" section of boatdesign-several of them. There is also a recent thread about an 18' canting keel boat-with specs and picture.
    Sounds like you might be interested in something like the Bongo but with a canting keel instead of a fixed keel.
    Of course, the lightest,hardest to sail and pretty nearly the fastest saiboat(mono or multi) under 20' is the incredible foiler Moth. But that may be a tad too much adrenaline and definitely not too good for two.
    Bongo (retractable) Keelboat
    Address:http://www.sailabongo.com/m/_general/reports.asp?riIDReport=11&CAT=1
    ----------
    18' Canting Keel Single/Doublehander - Boat Design Forums
    Address:http://www.boatdesign.net/forums/showthread.php?t=17349
     
  9. d_sinsley
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    d_sinsley Junior Member

    i will check out the threads you suggested, I really am not interested in re-invinting the wheel. If there is a boat out there that will do most of what I want thene great. The Moth...... what a cool boat, but not really quite right..... but cool none the less. That is the idea though an adreniline ride for one and one that I can build, again this is more about building a boat than sailing one.

    This canting keel idea is sounding better all the time. The idea of gaining the same righting effort as that of another crew would be just the ticket.

    Thanks for all your help. I agree finding a hull design I like then making the mods would be a reall way to go.

    Thanks guys.
     
  10. d_sinsley
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    d_sinsley Junior Member

    on the subject of the canting keel, what kind of effort are we talking about to move the keel to windward. could this be done by hand with enough purchase without having ten miles of line to pull it into place? Or maybe a small selftailing winch? A sigle handed boat such as we are talking is going to be a hand full( and a mouth full as well tiller in teeth with main and jib sheet in each hand). Could the keel be eased before a tack/jibe manouver then when the tack/jibe is finished and sheets can be cleated, move the keel into position?
     
  11. d_sinsley
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    d_sinsley Junior Member

    talk about re-inventing the wheel.... The bongo is just about everything I want in a boat. So there it is someone beat me to the punch doesn't fill the need to build. but it is definetly a great looking boat.
     
  12. Chris Ostlind

    Chris Ostlind Previous Member

    There are a couple of other possible boats that deserve a look and easily fit that go-fast vison you have in mind.

    The Swift Solo http://www.westsystem.com/ewmag/21/index21.html

    The new boat being made available from the Northwest Maritime Center, the PT15 dsigned by Paul Bieker.
    http://www.nwmaritime.org/news/news_128.shtml

    The Swift is geared towards the solo sailor and the PT15 for crews. Both are buildable. You'll have to check with the NWC above to get the current status for building a PT15 for yourself. Still, any boat that has the performance imprint of Paul Bieker on it is pretty much gonna be a quick boat. Dude likes to go fast.
     

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  13. alan white
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    alan white Senior Member

    You are raising maybe 150# three feet... if you weigh that, it is the same effort as climbing three feet of stairs. One way, I mentioned, would be to let the wind do it by spilling the sails with the keel loose, and tilting the boat to windward, locking the keel, and drawing in the sail. Manually, you are coming about, letting the keel go slack mid-tack, hands full with crossing and one hand on the jib sheet... while also wanting to crank the keel up. Position in cockpit, seated to windward, hauling jib now... seems your forward foot has nothing to do--- a simple foot pedal pivoting on the sole, up about a foot---ratcheting (the ratchet reverses depending on which side the pedal is depressed from)--- two or three strong pumps (back against a rounded back support)--- when I was in high school I could push 500 lbs from a seated position with my legs (squat to full extension) and I was 5' 7". You would be pushing 150 with one leg three times, one foot at a time--- one-two-three.
    Might take a couple of seconds. The force requirement could be reduced of course, take longer (maybe less time if just right).
     
  14. d_sinsley
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    d_sinsley Junior Member

    alan,

    Do you spend alot of time at night staring at the ceiling when you should be sleeping. You have an imagination, the foot petal would be a really great idea once again. your feet really wouldnt be busy until the boat powered up and you need to slide out to hike or trap. Interesting thought
     

  15. d_sinsley
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    d_sinsley Junior Member

    the swift looks like a good boat, I have looked over the internet for single handed performance boats and really didnt find much, through this forum I have come up with some great ones. And a wonderful discuss on an interesting modification. A Bongo with a canting keel. The solo may be a near future boat that seems very do-able. Thanks guys
     
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