Setting up a sailing dingy to sail without center/lee board?

Discussion in 'Sailboats' started by hospadar, May 10, 2020.

  1. hospadar
    Joined: Apr 2011
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    Location: Michigan

    hospadar Junior Member

    I recently finished a nice little bolger cartopper and am loving it a lot. I built it without any of the "sailing parts" - no centerboard trunk, no mast step/partner as I primarily just row and small outboard around with it. I recently came into possession of an older Zuma dingy whose sail is about the same as the specified sail area for a bolger cartopper and I've been pondering setting up the cartopper for sailing. The Zuma is too heavy [for me] to put on top of the car and it'd be nice to have the option to sail the cartopper (with the zuma rig so I don't have to make a new rig for the cartopper).

    My main hang-up is that I absolutely will not put a centerboard/daggerboard trunk into the cartopper (I often row around with 3 or 4 adults in the boat and wouldn't want to loose my cozy seat in the bow) - that being said, I've been pondering my options on how to sail him (this one's a boy) without a centerboard. I've heard that the cartopper gets most of it's lateral resistance from the rudder and the centerboard isn't very big (half a sq. foot I'm guessing?) so I probably don't even have too much to make up for?

    I'm thinking:
    1. Leeboard (duh)

      • I have a welder and could probably slap together some kind of arrangement that clamps on to the gunnels and drops boards over either side. Seems a lil clunky but OK.
      • On my first boat (a lovely summer breeze that was tragically crushed by a falling tree) I had a single leeboard that had a rope tied to the top end and to the center frame. I could throw it over the lee side and the water would press it into place (I think someone here suggested it to me!) very simple and worked great but kind of a hassle since you had to drag it out and throw it over on every tack.
      [*]No boards at all!?
      I've been reading the excellent Beachcruising and Coastal Camping and was reminded of Matt Leyden's boats which are generally board-less and rely on chine runners (and hull shape I suppose?) for lateral resistance.

    I'm really interested in option #2 - my cartopper is currently without any keel, but I'm wondering if a tall-ish (1.5"? 2"?) keel (or two?) would give me enough lateral resistance for halfway-decent sailing. By my math I'd have more than enough area, but I get that a long flat keel isn't the same as a board sticking down.

    I'm going to give it a shot because having a lil keel won't hurt - Think it will work? Will I end up throwing over a leeboard with a rope? One keel or two keels?

    Things I definitely do not care about: sailing really fast, super great upwind performance
    Things I definitely care about: number of things I have to pile into the car to use the boat, probably would be nice to sail even a lil tiny bit upwind ever.

  2. trip the light fandango
    Joined: Apr 2018
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    Location: Rhyll Phillip Island Victoria Australia

    trip the light fandango Senior Member

    A small full length keel should work, a rudder that has some area forward of the pintle/ gudgeon pins should help balance some of the extra load...I think...
  3. brendan gardam
    Joined: Feb 2020
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    Location: east gippsland australia

    brendan gardam Senior Member

    i fitted a windsurfer rig on a 12 ft flatty once, added a rudder and i made a ply leeboard that dropped into a slot on the outside made from 2 steel straps. very simple and worked well. because flat bottoms don't heel too much i only needed the 1 leeboard. [ i should have said that flat bottom didn't heel too much. i don't know what others do].
  4. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    If you are willing to row upwind as far as you want to go, then you can sail downwind with no centerboard or lee boards. The term downwind is intended to mean very nearly directly downwind. If you want to sail some other direction, say such as sideways to the wind, you are going to need some boards of some kind. You are opposed to a centerboard trunk. Understood. It can be in the way in such a small boat. The case as shown on the plan is pretty far forward and only 15 inches high. with a bit of modification it could be lower and have a seat top.... I have such an arrangement on my small boat.

    The Cartopper specifies a sprit boom sail of 59 square feet or a peak sprit of 61 square feet. You will need a board of somewhere near two square feet if the boat is to sail well. That is about the size of the designed board when immersed. Bolger and Payson had these details figured out very well. Cartopper is a pleasing little boat that performs well. It would be a shame not to give her a good sail rig including some kind of board. Her bottom is a bit narrow but the bevel chines (sometimes called trapeze bottom) will pick up some righting moment quickly. The sides are flared a little bit so that makes lee boards somewhat problematic.

    Runners or one by two strips on the bottom would help, but not by much. They add some wetted surface and cause some turbulence which is unwelcome when rowing. They do help to protect the bottom when beaching the boat and they help to prevent yaw. She will not tack as readily if you install the runners.
  5. hospadar
    Joined: Apr 2011
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    Location: Michigan

    hospadar Junior Member

    Thanks for the replies!

    @messabout I hear you - my thought was that if I REALLY loathe whatever goofy setup I come up with, I can always cut a hole and put in the centerboard later.

    I just had another [crazy?] thought - what about a longboard or windsurfer fin (or two or three)? (probably with a breakaway screw in case I run into a log or beach). I row a lot more then I'll ever sail so the inconvenience of screwing it on is probably not a biggie (and again, if it's horrible I can always bail and install the centerboard).

    It would be easy to bed the fin box inside a runner and you can get blanks to fill up the fin box when not in use.
  6. gggGuest
    Joined: Feb 2005
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    Location: UK

    gggGuest ...

    The issue you have is that whatever device you fit to provide side force in the water will have much the same load on it as the sail has in the other direction. So it does require a fair bit of strength. The reason the daggerboard is so popular is because the alternatives usually end up being even more trouble. One can imagine, for instance, keels that bolt onto the bottom of the boat, but then the damn bolts will leak... In an ideal world I would have a sailing boat for when I wanted to go sailing, and a rowing boat for when I didn't, then neither would be horribly compromised by trying to make it do two different jobs... You'll probably find with a reasonable rudder the boat will go a good way from dead downwind without a centreboard, but not a hope of sailing against the wind.

    Thinking aloud, If you want to try weird stuff it might be interesting to have a large rudder and a board that somehow clips on the bow. That would be easier with less of a spoon bow though. The trouble with doing weird stuff is that you have to be able to laugh as you chuck that stupid idea in the skip after it proved to be totally useless within the first 5 minutes....
  7. wet feet
    Joined: Nov 2004
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    Location: East Anglia,England

    wet feet Senior Member

    As has been posted,you can row upwind and sail maybe up to just above a beam reach.A permanent fin on the outside won't live very long and will be inconvenient to fit and prone to snapping.How deep are you willing to wade each time you launch and recover?A daggerboard may just give you more of the treasured seating space as you can make a T section temporary cap with a wide enough top section to sit on.It isn't so hard to make a case for one but do be sure to give it enough lateral support as the forces on it are equal to the forces generated by the sail-or very nearly so.A pair of transverse knees reaching almost to the chines would do it and you would need to remember to allow for drainage.I wouldn't really want to sail a boat that small with 3 or 4 adults.

  8. sharpii2
    Joined: May 2004
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    Location: Michigan, USA

    sharpii2 Senior Member

    The way I see it, you have two real choices.

    1.) A LONG KEEL. This would have to be about 5 ft long and about 0.5 ft deep. Making it longer will not make it reduce it's required depth by much and will add to whetted surface you will have to drag through the water. This will increase your draft considerably, but will not cause the rowing drag that a permanently extended deeper keel or board would. It will also not go to windward like one. You may make as little as 1 ft upwind for every 3 ft you move forward.

    2.) A SHIFTING LEEBOARD. This could take the place of the rowing seat when rowing. It could be supported by blocks on either side of the boat and maybe a removable center support. When rowing, the board acts as a seat. The flange, which holds its top at gunwale height, faces up. When sailing, the board is lowered over the side, and the center support is removed. A limit line keeps the board from sliding aft. Pegs on the flange keep it held to the gunwale. Leeward pressure holds the bottom against the hull. When changing tacks, the board, the board is rotated so the flange faces inward on the new side. Now this makes sailing to windward much work, but this boat is primarily a rowboat, so such additional labor may be acceptable. The board need not line up with the centerline with a boat with as soft bilges as soft as this one, but the closer you can get to that the better. You need not add hull guards to keep the board vertical. The topside flare of this boat is quite mild. Yes, you will lose some efficiency, but not all that much.
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