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Some wood, some brass, Todd' book...

Discussion in 'Canoe Sailing' started by Louis Michaud, Aug 27, 2007.

  1. Louis Michaud

    Louis Michaud LOVES Wooden Canoes

    ... and a whole bunch of assembled parts later...

    The sail is from a you-sew-sail-kit. Easy to do with the instructions BUT(!!!) I've learned to hate sewing dacron: darn vicious stuff to work!!!!! Next sail is going to be made of flannel...

    Follwing the w/c canoe repairability philosophy, most everything is mechanicaly fastened. The only areas I used glue was with the brass bushings for the leeboards/rudder and the mast step sole. I know I went overboard (!!!!) with the complicated drop-in yoke/rudder unit. I wanted a traditionnal yoke with a drop-in unit so I could sail any canoes with the least modifications to the canoes. The drop-in rudder works as it is, better with a coming modification. Aesthetically ? You tell me...

    The only modification needed on a canoe is the addition of a mast step sole only 5/8 inches thick. Less work than adding a full mast step to each canoe and is also less obstrusive.

    The only problem is with the yoke linkage: the yoke pivot is offset with regards to the rudder "hinges". This has a reduction ( or multiplication ?) effect. Only 4 inches of rope travel are needed to get the full rudder range from one side to the other, steering is a bit hard and not very sensitive. I'll have to make a longer link arm .

    Had a lot of fun making the rig and having a great time sailing, along with a few adrenaline rushes: never sailed and have no idea what the heck I'm doing.
    The only thing I would maybe change is the sail type: the boom on this standing lug is low (or maybe the mast is too short?) and gets really annoying (Boink!!!) when doing short legs on a narrow lake. Maybe a flannel leg-o-mutton with a sprit-boom...

    Best,

    Louis Michaud
    Rimouski, Quebec
     

    Attached Files:

  2. Todd Bradshaw

    Todd Bradshaw Sailmaker

    Outstanding! This is what makes the headaches of writing a book worth it. And yes, Dacron can be a bit annoying to work with, though you eventually learn or figure out a few tricks that make it at least tolerable. If nothing else, flannel could be colorful!

    As for getting hit by a low boom, You look like you might be able to lengthen the mast a bit and get away with it, though as you get used to sailing the boat it's one of those issues that pretty quickly become non-issues and keeping the sail fairly low can pay off in the long run. Read up on the "Forced Cross" (page 22, right column) which is simply a method of grabbing the boom and passing it over your head at the proper time, rather than waiting for it to cross over on it's own. Learning the timing and getting good at it will both speed up your tacks and pretty well insure you're not getting beaned while tacking or jibing. Learning to avoid "sailing by the lee" (page 15 lower left) is also worth studying as that's where you're in the most danger of the boom coming across unexpectedly and with enough speed and force to do some serious damage to your noggin.

    Great job!
     
  3. OP
    OP
    Louis Michaud

    Louis Michaud LOVES Wooden Canoes

    Thanks for the compliments and suggestions!
    I looked up "sailing by the lee". Been there, done that: got wet! My cowardly dog abandoned ship and swam to shore and stayed there.

    Still curious about the sprit boom rig. With the basic sailing rig done, different sails for different canoes! I would not use flannel, instead I would use a high count cotton/polyester material and tan it using a traditional French fisherman's mix. This could be addictive...

    If you don't mind, just how is a sprit boom leg-o-mutton sail shaped? Say a 50 sqft with a reef band, with broadseaming or edge cutting?
    Thanks.

    Louis Michaud
     
  4. Todd Bradshaw

    Todd Bradshaw Sailmaker

    He reaches into the big Box-O-Rigs and pulls out ....a 50 sq. ft. sprit-boomed Leg-O-Mutton in the always fetching Tanbark color....

    It's easier to shape this sail using a cross-cut panel layout than it is with a vertical one as it allows more straight-forward broadseaming. Shape is a mixture of three things:

    1- You would add luff curve to create draft to the tune of about 2" added in a smooth convex curve from peak to tack with the maximum round about 45% of the way up from the tack corner (technically, in doing this, we're adding around 2%-2.5% of chord width up and down the sail for the luff curve).

    2 - you have to add more to the luff curve because of the mast bend that is to be expected with a sprit boom rig (the "bow-and-arrow principle"). This is always a crap-shoot, but I suspect that an extra 2"-3" will be needed for a typical canoe-sized mast. Too much and the sail will always have deep draft. Too little and it will tend to be overly flat most of the time as the mast bends in use. So...if we're adding say 2" for bend and 2" for draft the actual luff round added will be 4" and it's full depth will be about 45% of the way up the luff edge. On a one-off, first attempt with no high-powered computer simulation, about all you can do is make your best guess on these things and see how it works out when you get out on the water.

    3- To then help move the extra fabric added to make the luff curve into the middle of the sail (where we want the draft) we use broadseams. Again, broadseam curves and sizes are estimates. A typical broadseam curve is drawn on the attached plan in pink (it's hard to see, but it's there). Broadseams (gradual increases in the panel-to-panel overlap at the seams) would be made on those seams which fall to the right (forward) of the pink curve. We start broadening the seams (increasing the panel-to-panel overlap) at the curve and they get gradually wider as we approach the luff of foot edges. Obviously, the number of panels dictates the number of seams that can be broadened and the stability and stiffness of the fabric being used also has an effect. Stiff fabric (Dacron) needs more increase in overlap than softer, less stable fabric (like cotton) which will stretch more in use. Narrow panels may be fine with a whole bunch of small overlap increases (1/4"-ish) where a sail made from wide panels may only have three or four available seams and they will need to use bigger overlaps to generate the same amount of total combined broadseaming. The "tack seam" (the one that comes closest to hitting the tack corner- lower right) is the longest and is also generally the one with the most ability to transform the sail from a flat construction to one that has real, three-dimensional shape. Tack seams will usually have a pretty substantial broadseam overlap, often in the 1.5"-2" range at the corner, even on a small sail like this one.

    You want your broadseam overlap increases to be gradual and smooth tapers to avoid wrinkles or hard spots in your sail and then just as you get within a few inches of the edge, you flare the overlap slightly (increasing it even more) as you come to the edge. This makes the leading edge of the sail a little rounder, which in turn makes the sail easer to trim properly to the wind and the boat easier to steer without stalling out the sail due to slight steering errors.

    Note that these shaping techniques will also change the perimeter shape of the sail a bit. So, you work with a slightly over-sized, rough-cut hunk of fabric over a plan taped-out on the floor and you don't cut your final perimeter shape until after the seaming and broadseaming is done.

    The foot edge on a sprit-boom sail of this size is best cut straight with no round between the tack and clew corners. This is because the sprit-boom assembly creates a line of tension between these two corners. Any round on the bottom would extend below this line of tension and likely just flap in the wind with no good way to control it.

    The reef line should have quite a few patches and reef ties, because the bundled-up bottom of the sail is going to be hanging out in the wind, below the working sail area when you're reefed and you want it to stay bundled-up.

    I've shown the mast raked aft a bit on the drawing, mostly because I like the looks of it on Leg-O-Mutton sails, but it could just as easily be straight up and down. The halyard is run forward to act as a makeshift forestay for a little more mast support, but could also just come down right next to the mast.

    Anyway, that's pretty much the way I would shape the sail. A copy of Marino's book "The Sailmaker's Apprentice" or Jim Grant's booklet on Mainsail Construction (from Sailrite) would help explain the fine points. If you can find some of the tightly-woven poly/cotton like they use for making mountain parkas, it would probably make a pretty nice sail.
     

    Attached Files:

  5. OP
    OP
    Louis Michaud

    Louis Michaud LOVES Wooden Canoes

    Thanks a lot! I appreciate you taking the time.
    This will be this winter's project.
    Right now I'm working a compact and simple to rig downwind sail based on the BSD TWINS concept, which is basicaly two leg-o-mutton sprit boom sails on the same mast.

    Thanks again.

    Louis
     

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