Brainstorming

Discussion in 'Sailboats' started by messabout, Jan 27, 2019.

  1. messabout
    Joined: Jan 2006
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    messabout Senior Member

    I am about to build a tiny little eight foot sailing dinghy, a pram or possibly a pointy dink.. There is very little foot room in such a wee little boat because the dagger board case is in an intrusive location.

    What are your comments about offsetting the case to port or starboard about 18 inches? The mast could be offset about 10 inches if it mattered. The downside that has occurred to me is that if heeled severely toward the side the case is on, then the case could let water into the boat out of the top of the case. this could become iffy when heeled at ....say 20 degrees. At that angle the skipper is already in trouble.

    An offset mast could make a problem if capsized to the offset side of the boat. But how about the vectors? I can see no real problem but your comments are solicited.
     
  2. rwatson
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    rwatson Senior Member

    I think you should consider leeboards. They aren't stylish, but they make a lot of sense for a small boat.
    You don't even have to have them both down in many instances.

    An offset mast would only work with low aspect sails - so the problem of righting from the "wrong" side would not be a problem.
     
  3. Tiny Turnip
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    Tiny Turnip Senior Member

    what rwatson said.
    gotta love a leeboard.
     
  4. trip the light fandango
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    trip the light fandango Senior Member

    If the dagger board is offset it may make righting harder also, a low longer case with a concertina retractable fin strong enough to stand on to right, modern materials and all.. ha ,.. you did mention brainstorming or is mine brain fade ..? ha , cheers .
     
  5. Ike
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    Ike Senior Member

    leeboards are good. When I was a teen my Dad and I built a 14 ft sailboat with leeboards and they worked rather well. However there are other ways to solve this. About ten years ago I built a 7' 11" sailing/rowing dinghy and went through the same thought process. What I realized was I could reduce the height of the dagger board trunk so it fit completely under the thwart/seat. When I was sailing I sat on the floor anyway to lower the CG and not on the seat, and when rowing I didn't need the board. see Boat Building Projects | Building a Sailing Pram | Page 2 http://newboatbuilders.com/pages/Dinghy-2.html
     
  6. trip the light fandango
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    trip the light fandango Senior Member

    How aboutt a neat wooden swivel arrangement so the windward leeboard can be sat on [ a little folding prop under it]. At anchor raise and turn them both and hang little buckets off the ends.., and put your lunch on one ,..with some elastic,.. after some thought leeboards add weight and complexity you don't need,... a neat waterproof case under ,..ie ..Ike.. the seat is better, with an inspection panel in case it gets jammed.. cheers
     
    Last edited: Jan 30, 2019
  7. Doug Halsey
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    Doug Halsey Senior Member

  8. messabout
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    messabout Senior Member

    While brainstorming the offset board thing as well as the offset mast possibility, I came up with an idle observation. It goes like this.....If the mast is offset from the center line of the boat, then the lead on one tack will differ considerably on the other tack. Perhaps not a big deal but it might not work well for a sailor who is not accustomed to such vagaries.

    Thanks for the replies gentlemen. Although lee boards have a bad rap, I know that they do work. If I built a movable bridge for the board support then I could tinker with different sail configurations with some assurance that I could achieve some sort of rig balance........as if it mattered with such a tiny little boat.

    I chartered a Bolger Black Skimmer for use in Florida Bay many moons ago. Bolger's lee board arrangement was a study in convenience and they worked just fine on that odd ball but marvelously efficient boat.
     
  9. messabout
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    messabout Senior Member

    Doug I have some familiarity with the Sabot, El Toro, and a few others. They are, for their purpose, nifty little boats. I have a somewhat different agenda however.

    I have a very competent 16 foot flattie that I sail for fun, row for exercise and use to go fishing once in a while. The flattie, named Goldilocks, is on an easily loading/unloading trailer. For a half hour of playing in the water the trailer is a PITA. I would like a little boat that will fit into the back of my Honda Element. It can be only 42 inches wide and I want it to be an ultralight weight boat so that I can easily load and unload it Traditional prams are disqualified because of the width restriction. (incidentally, I am an Octogenarian in good health but not particularly enthusiastic about lifting heavy weights)

    There are three sheets of BS1088 4mm Okumee ply and one sheet of 6mm that have been languishing in my garage for a long time. I can use that stuff to build a mini skiff for a little bit less than 50 pounds. The stringers, keelson, transom framing, and all those things will weigh nearly as much as the skin. Some 4 ounce glass on the bottom and a some paint might add as much as 9 pounds including the fillets at the chine and stem. Every ounce amounts to something so I am being stingy with any fancywork.

    I have some experience in designing and building small boats. Every once and a while I get lucky and manage to get it somewhere near right. A pram like planform has a little bit more initial stability but the pointy skiff fits into the Honda more nicely. My town of Lakeland, Florida is aptly named because we have dozens and dozens of lakes in which we can drown, or get eaten by the alligators. The mini boat will never see much weather or tricky water so I can probably get away with a narrower than conventionally advisable little dink.

    I will post some pix of the quarter scale model if the posts warrants further commentary.......Aside from that, I wish every one a prosperous and happy new rotation of this earth.
     
  10. sharpii2
    Joined: May 2004
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    sharpii2 Senior Member

    The biggest problem with offsetting the mast on a pointed bow boat is that it looks a lot more odd than doing the same with a square bow one. If not worried about such appearance, why not go for it?

    A solution for your over topping problem might be a single lee board. A ten-foot long box boat I have designed has this system. The lee board is secured at the top with two lines. One leads to the bow (to keep it from shifting aft and to keep it connected to the boat so it won't get lost) and another attaches to a hook which grabs the inner cockpit edge (see sketch).

    If the board hits an obstruction, the unsecured bottom is free to move aft. At this point, the cockpit hook may come loose leaving the bow line as the only one attached to the boat and the lee board. The lee board can be pulled out of the water and the hook reset. This lee board is intended to be shifted over to the lee side with every tack. The foil is symmetrical for this reason. I settled on this system because I wanted to build this boat out of just three sheets of plywood. There wasn't enough material to make two lee boards.

    This design is intended to go sailing when the wind is good, but to go after pan-fish and bass when it isn't.

    I am definitely interested to see what you have come up with for a design. I hope to see at least some sketches.
     

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  11. gggGuest
    Joined: Feb 2005
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    gggGuest ...

    Lake scows, bilge boards, even catamarans, the world is full of boats that don't have the board on the centreline, so clearly there's not an intrinsic need for the case to be in the middle. So the only question would be how degraded the performance will be with the board on the 'wrong' side. Make the board a bit longer and its probably not that much, and still more efficient and less cluttery than a leeboard. Put a case each side and you could put the board in whichever side makes more sense for the current voyage, and you could even have a short dummy board that doesn't go below the bottom of the hull to fill up the gap on the other side and stop water sloshing up.
     
  12. Ara
    Joined: Jan 2016
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    Ara Junior Member

    How about compensating for the lack of left/right symmetry by introducing forward/backward symmetry?
    This would solve the issue of an offset mast raised by rwatson (kitesurfers - at least the non-foiling ones - have their shrouds only to the windward side of the kite).
     

  13. messabout
    Joined: Jan 2006
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    messabout Senior Member

    It has finally occurred to me, that offset boards are not much of a problem. My M20 inland lakes scow had twin boards and a center located mast and it worked just as well as a conventional in line configuration. No need to offset the mast it would seem. I have crewed on other boats like E scows that had twin boards. The E and the A go like demons and handle most satisfactorily. I just woke up enough to remember these things....... evidently.

    The difference between the scow layouts and the silly little dink that I contemplate, is that the scows are designed to be sailed on their ears and thus they have offset twin rudders. No such thing with the dink. It might be steered with a single oar that can do double duty as a sculling tool. I will not be voluntarily sailing the dink at steep heel angles either.

    Sharpie2, I think that flat bottomed boats are sure enough practical and they do work pretty well within limits . For a little dinghy that is not likely to ever go as much as 4 knots, the additional wetted surface of the flattie is not that big a deal. I have an oddball way of building such boats. I build them right side up and do not use stitch and glue methods. Drilling holes and lacing wire is not my cup of tea. Neither is the tedious layout of the four parts. I use a simple series of wooden wedges that holds the parts in place while I get my fingers , gloves actually, all gunked up with epoxy fillets.

    If there is any interest in this method I will try to describe the details in another post.

    Cheers to one and all .
     
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