Sail Rig for Canoe

Discussion in 'Sailboats' started by ancient kayaker, Jun 12, 2011.

  1. ancient kayaker
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    ancient kayaker aka Terry Haines

    After a long interlude I want to get back into sailing a canoe; I have a couple of candidate wooden canoes, one hard chine and one with rounded bilges.

    Amas: not being young or athletic I need additional stability for safety, to give me extra time to react to wind changes etc. However, I plan to keep the amas out of the water most of the time as they can be a drag, literally. In the past I have found that canoes sail much faster with the amas flying.

    For this application a planing design would work better than a displacement design, as well as being more compact, something that would have good buoynacy for its size and not tend to dive into a wave at speed. My thinking is to use a Garvey style ama; the pounding associated with some garveys would not be a problem while they are flying and I think they would plane readily if dipped at speed.

    In the attached sketch I show amas of about 48 lb (22 kg) displacement when immersed, with 27 and 47 sq ft (2.5 & 4.4 sq m) on a 12' (3.6 m) canoe; the larger sail will require battens, and there will also be a leeboard (10% of sail area) and foot-controlled rudder, but these are not shown.

    I would appreciate some comments on my thoughts for the amas and rig.
     

    Attached Files:

  2. CutOnce

    CutOnce Previous Member

    Terry:

    Looks like fun!

    I've sailed canoes like this, and have found the lower you keep the sail area, the better. If you are alone in the boat, you can easily tack and gybe "behind" the boom (as many do on International Canoes now) and therefore there may be little reason not to bring the boom down. You could leave the taller mast, so if you do convince the missus to go, just raise the sail higher.

    --
    CutOnce
     
  3. Doug Lord
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    Doug Lord Flight Ready

    ------------------
    Terry, I think it depends on your speed-you don't mention ama length. Hull speed on the canoe will be around 4.5 knots.
    I tried a 2' ama and theoretically it will plane at 2.82 knots(depending on load) so if you're going faster than this it will work well- below that it will be a lot of drag, but so what?
    I think you might be better off with a gaff rig at the same CE height-it will allow you to have controllable twist which will allow you to easily depower. It is also aerodynamically better than the short span pointy rig. It will move the CE aft some so you'd have to consider that...
    Looks like you'll have a lot of fun!
     
  4. ancient kayaker
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    ancient kayaker aka Terry Haines

    I tried 2 alternative sail plans, a 36 sq ft balanced lug and a 27 sq ft sprit shown here with the original 27 sq ft bermudan. because of its high peak the B-L doesn't lower the CoE but the sprit does, although it is limited to a smaller area than the B-L. The CoE fore-aft position is governed by where I want the leeboard to be for easy access. The entire rig, amas included could be moved a foot or so forward but it doesn't help matters particularly. The paddler's location in non-negotiable!

    The original boom could be a bit lower, and could become a sprit to add area and lower CoE at the same time. Being wacked by the bottom edge of a spritsail is less dramatically educational than a boom and either will teach you to duck. Another option is to add a jib.

    A further factor is the presence of low bridges in my closest sailing location, which favours a rig that is easily dropped and raised. Also high banks and a lot of trees may give the advantage to a taller rig.

    Onviously I will need to experiment.

    Do you think it would be smart to increase the ama size? They are nice and compact at present but I can add another 50% buoyancy for 75 lb each, fully immersed. I will arrange for the mainsheet to be hand-held so it can be released quickly.
     

    Attached Files:

  5. messabout
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    messabout Senior Member

    If you have bridges or other height constraints, you could consider a sliding gunter......even a peak sprit gunter.
     
  6. ancient kayaker
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    ancient kayaker aka Terry Haines

    These are LOW bridges, I can touch the frame with my hand as I paddle underneath, so the entire mast must drop. I plan for a rig with no standing rigging and few parts, that can drop to one side of the paddler and still leave room to paddle under the bridge.
     
  7. sharpii2
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    sharpii2 Senior Member

    You show no keel/lee board/dagger board here. The position of that relative to where your sail is determines the balance of your boat. I would go with a square sprit sail, if I were you. It requires on sheet, no halyards, no boom and, with a well set up braille line, collapses in three moves.

    1.) relieve the sheet.
    2.) pull in the braille line, and
    3.) pull the mast out of its step.

    Thames barges were supposedly able to approach a bridge, lower the rig (with a powerful windless), shoot under the bridge with their momentum, then pull the rig back up, without losing way.

    I presume you're after similar convenience.

    A taller rig is not consistent with ease of stepping and un-stepping.
     
  8. ancient kayaker
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    ancient kayaker aka Terry Haines


    The square spritsail sounds a good idea, low CoE, nothing hard to bang my head with and simple.

    I’m not sure I want to have to lift the mast from the ste, these are small canoes that do not encourage strolling about. However, I can use a pivoted mast with the square spritsail since it permits a shorter mast for a given sail area, and I can raise it with a forestay. I can take the braille back to the cockpit, but I may try an arrangement to tighten the braille by raising the mast - once it is adjusted.

    I have a daggerboard from my sailboat to use at first, it’s about the right size. I plan to hang it over the side and move it about until I find the best fore-and-aft position, but I won’t finalize it until I have done trying various rigs. After that a new leeboard can be made that attaches to a removable minideck that will also support he outrigger beam and mast pulpit.

    Many thanks to all for the interest and suggestions.
     
  9. sharpii2
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    sharpii2 Senior Member

    Yeah.

    You could use a tri stay system with one back stay shorter than the other, so the mast can be off set. This way the mast can lay down beside you rather than on top of you, when it comes down.

    I think you are going to need stays to hold up the mast in order to transfer the heeling moment to the outrigger cross beam. Otherwise, twisting loads will be put on the canoe itself. Loads it probably wasn't designed to take.

    Once the lee float immerses, the initial stability will be quite high. From your sketch, I estimate the floats are at least 4.0 ft from the center line.

    just for fun, I will show a sketch I made for a strap on canoe/kayak sailing rig.

    I put keels on the floats to limit draft and to reduce operational complexity.

    In order for this set up to work with a square sprit sail, a jib will have to be added to get the CSA and the CLA to line up.
     

    Attached Files:

  10. ancient kayaker
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    ancient kayaker aka Terry Haines

    I wanted to minimize stays as they get in the way when paddling with the mast down. I noticed in your sketch you have the mast and cross-beam joined. If I do the same and attach the leeboard to the same assembly the heeling moments and forces will cancel before they reach the canoe hull. Shrouds should not be necessary with a strong mast and pivot.

    Hull stress will occur when the wind forces are balanced by body weight to keep the floats out of the water, which I had not realized before. However the canoe is too narrow to allow me to get far off-center so there is a natural limit to that. I suppose - if there is a lot of twisting - I can add reinforcement.

    I've seen the keels on the floats before someplace but can't recall where. It's a nice concept as only one will be in the water at a time; that raises the interesting idea of giving them toe-in to cancel leeway. However it would be a problem launching from my beach which is shallow for a long way. It would force me to carry the bits way out into thew ater before I could assemble it, so I will stay with the pivoted leeboard.

    The lateral areas in your sketch look more or less balanced to me, I don't see the need for a jib, but it's something that can be added to the forestay if needed. The most likely thing to cause that is if the leeboard has to be so far aft it gets in the way of paddling; I use a double paddle - kayak style - for these small canoes so it's a potential problem that a jib would solve by moving the CoE forward.

    I'm glad you mentioned beam; it reminds me that the troublesome bridges have rather narrow gaps between the piers and abutments; I need to check them for space - I made the crossbeams about the same length as a paddle, but a paddle is a lot easier to lift out of the way.
     
  11. sharpii2
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    sharpii2 Senior Member

    I think you should ask yourself what the purpose of the sail rig is. Is it to supplement paddling, or replace it.

    If the purpose is to supplement paddling, a much different set up should be drawn. I'm thinking twin boomed latteen sails, one forward of the paddler and one aft. The sails would be flat cut and would be of about 15 sf each.
    A removable lee board would be used when it gets too windy for easy paddling. The sails would be raised and the lee board put in place. A rudder would not be needed, as the steering can be done with differential sheeting.

    The sails can be raised remotely, with halyards leading to the cockpit. The yard and boom would be just under 6 ft long each.
     
  12. garydierking
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    garydierking Senior Member

    You can use an unstayed mast as long as you put a stiff bulkhead or ringframe near the mast.
    A boomless spritrig is easily brailed up when you want to paddle.
     
  13. ancient kayaker
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    ancient kayaker aka Terry Haines

    I have only come aross the term ring frame in the context of spinning and data systems. What would one look like on a boat?
     
  14. MalSmith
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    MalSmith Boat designing looney

    It means a frame, as opposed to a bulkhead, which forms a closed ring. That is, it supports the hull sides, hull bottom and the deck.
     

  15. hoytedow
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    hoytedow Wood Butcher

    ;)
    I have one 60 year old eye that works. It doesn't work well with chartreuse, so please use a darker color when posting great advice. ;)
     
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