Skate Sail Fabrication
Parts list & instructions
Seams: Assume ¾ inch all around for double folded ~1/3” seams. Use light canvas wrapped in sailcloth for mast ends & clew, where grommets are installed.
Grommets: Clew grommet as close to corner as practical (in canvas or extra fabric hemmed into triangle). Mast sleeve outhaul grommets at corner of folded mast sleeve, tangential or on the opposite side of the pull under load (wait to drill grommet holes until you put completed sail on mast. Grommets I used were ¾” with a 3/8” opening.
Holes for clevis pins: Drill holes in mast last, after sail is sewn. Mast end holes should be drilled for clevis pins, with washers if necessary to secure ends of where the grommet holes naturally lay when sail is placed on the mast-maybe with a little added twist to maintain tension. Lengthwise, mast end
holes should be placed to stretch length mast sleeve by about ½” from slack, depending on elasticity of fabric. Avoid overstretching mast sleeve (“downhaul”).
For low winds can have second hole approx. 1/3” shorter.
Cut length of mast & boom last, after sizing. Will want to have mast as short as possible to avoid dragging, and boom as short as possible for optimum trim. Boom and mast lengths will be
about 5’7” and 9’5”. I would advise sewing the sail first and making the poles a little long, to be cut last. Some kind of nylon or plastic plug would be good for mast ends, so it slides instead of
digging in if you unintentionally drive it into the pavement in front of your skates or skateboard. (most common error – results in nasty falls).
Mast sleeve requires 6 inches of fabric. 1 inch for a double-folded ½” seam, and 5 inches for the 2-1/2” wide sleeve. Two inch taper makes the sail cup slightly. If you are joining two 36” panels, you can create an additional 1 inch of taper, starting about 14” out from center when you join them. (If you go with three linear panels of material sewn together (e.g. to create two clear mylar windows on the outer thirds of the sail), you can cut similar tapers in the fabrics on the clew-ward portion of the sail). Both these tapers can be rounded slightly for a more gradual tuck. Your seamstress should be mindful of
distributing the ‘tuck’ smoothly. This is the hardest part of the sewing job.
After marking basic triangle of sail and centerline, measure out about 27” inches from center on each side and
at that line, and use that as the point to extend the edge of the basic triangle 5 inches out to give the sail a little shoulder.
For a collapsible mast, you’ll want to take it to a metal shop and have the 7” x 1” x 1/8” band welded on to serve as the boom attachment. Make sure they don’t occlude the opening, so the thinner tube from a telescopic swimming pool vacuum handle, which comprises the other half of the mast—can slide into it.
Plan on about 18” of the thinner tube inside the outer tube when the mast is at full length. Then a clevis pin inserted near the boom bracket will fix the inner tube in place. The advantage of the
collapsible mast is that it will go down to about 85 inches, so it will fit more easily in a car.
If you intend put it on a rack, you better have it wrapped real thoroughly or in a ski-bag, because the drag will catch any loose flaps and beat the fabric up pretty fast.
If you decide to go with a simpler non-collapsible one-piece mast, for a boom bracket you can use a 2-1/2 pipe bracket bent into a ‘U’ and slip a bolt to it (since you don’t have to worry about sliding a smaller tube inside it).
Outhaul: To secure the 3/8” rope that tightens the sail at the outer end, I cut a slot in the end of the boom and put a sailboat pulley-cleat in the middle of the boom with a bolt through it to hold it in place. You could also probably install a pulley wheel in the end and manually cut a v-shape cleat in the aluminum tubing.
Other improvisation is possible, but you want it to hold it pretty secure. You don’t
need to design it to be tightened under sail, since it takes two hands to hold the sail anyway. I
tried using the telescopic feature of the swimming pool bars to tighten and loosen it, but I was in a sandy environment and it got clogged up. Plus I don’t think they’re intended to work under load like that.
Batten sleeves; 1-1/2” sleeve for sliding in a ¾ batten or wood strip. Add
¾ to the width of the fabric for two approx. 1/3” seams—for a total of 2-1/4 before folding and
sewing. No need to double-roll the seam. Sew on some nylon webbing with a fastex clip to hold the batten in place after you insert it. The batten sleeve should reach all the way to the seam of the mast sleeve.
You can reinforce this junction for wear or better shape, but I didn’t. You can get by without battens, especially with stiffer fabric that won’t luff.
Battens themselves can be purchased from a sailboard shop or website, and cut to precise size.
Some sailboard battens have a slot to slide the ¾” webbing through, or you can just run it around the end of the batten, and tighten it to load the batten slightly.
You can just use ¾” moulding or wood strips or other materials. You’ll want to
grind the leading 33% of the wood strip or fiberglass batten to make it form a better airfoil, that is, if the batten isn’t already tapered.
Feel free to play with the design. The main area where there’s room for adaptation is the ‘shoulder’ on the sail.
You can lengthen this beyond 5” and beef up your batten arrangement to give a little more area. Otherwise, adding power involves lengthening the mast. Adding length to the clew or boom won’t add much and may de-power your mastline pocket by degrading your airfoil. If you want to add power to
the sail; You can lengthen the mast to some extent. I’m 5’8” and the 9’5” mast isn’t a
problem, so if you’re bigger you could lengthen the mast. The sail design here will work in 20-25mph and up winds on pavement. I haven’t tried it with skis, but you may need more wind or a pretty good glaze on the surface to get effective performance.
Materials; Dacron hang-gliding material has worked best for me. It’s light
and non-stretching. I tried balloon cloth but it was too stretchy. If you can grab the fabric and stretch it on any dimension it’ll be too billowy.
Clear Mylar sections on the outer thirds of the skatewing might be good, or all-mylar. This could be tough to sew and taper, however. I don’t have any current sources for either material, but the internet should reveal some results. Another possibility is to buy an old sailboard sail (I’ve found them for $25) and just use that material.
Limitations might include being able to section out a piece that has a symmetrical ‘cupping’, since the booms are on the bottom third of the sail, and tapered from that point. Maybe choosing a section
farther up the sail will give you an even trim. Also the material may be hard to work with, for example folding may be difficult, but possibly you could just use a series of nylon webbing loops instead of folding it for the mast sleeve. Seams could be difficult, but cutting it with a hot knife or something may work in place of seams. Also the boom sleeves, should you choose to employ them, may not
be aligned right.
Sailing:M/h4> Hold your lead hand on the mast—maybe slightly above the boom-mast
junction, and rear hand on the boom.
Pull in on the boom to add more power. To reverse directions, flip the sail over and switch lead hands.
When handling the sail, keep the mast end into the wind, and the clew downwind. For steady state, or to go up wind, hold the mast near the junction with the boom and let the sail luff. You’ll need a
good quarter mile of open ground in front of your sailing line to get good, even wind. Buildings especially interrupt wind for a good distance downwind.
Sail trim; tight for sailing upwind, medium for light winds or cross-wind sailing.
Be ready to drop the sail if you get into trouble. That’s the beauty of not
having it attached. You’ll learn to reverse the sail by pushing the bar out for a very rapid stop.
If you’re sailing around a parking lot, you’ll generally be able to stick with one setting. For reaching back and forth on a bike path, you may need to change trim at the end of each run, if the wind isn’t perpendicular. It’s quite exciting because with the tight trim you can sail close to the 45 degree theoretical limit into the wind.
Safety
The biggest wipe-out avoidance tip is to make sure you don’t accidentally drive the mast into the ground in front of the skates or skateboard. This will send you tumbling pretty fast. You can brace the sail against your foot, or put a small cup on the front of your sailboard, or a U-shaped bracket at the bottom of the mast to place on your roller skate, but the sail is so light and the
drag so low that I haven’t found this necessary. For a little added efficiency, add a band around the clew end 3-4 inches up from the
attachment of the rope to bring the clew against the boom, maybe grabbing a little fabric along with it. This moves your anchor point forward a little to give a better
airfoil.
Make sure you wear knee and elbow pads, wrist braces, and a helmet. I add
padded hockey pants, a camel pack and a fanny pack with packing bubbles in it for spine protection.
Feel free to e-mail me if you need any more help.
Good luck and enjoy. [email protected]
For
single piece mast; ~9.5 feet of 1-1/4” aluminum swimming pool tubing.
For two piece mast; 4.25 feet of 1-1/4” and 5.75 feet of
1” tubing to slip inside the other piece with a 1.5 foot
overlap.* Can be purchased
at pool supply store.
For
boom; ~5’7” of 1-1/4” or 1” tubing.
Fabric;
5 yards of Dacron or nylon, non-stretch.
I used hang glider cloth. Sailcloth
can be used if it’s light—e.g. jib or spinnaker cloth. Full-duty
sailboat or sailboard sail material will add too much weight. If you go
to a fabric store-make sure there’s no stretch in the nylon or Dacron.
Possible source on the web for hang-glider cloth is willswing.com.
Two
2-inch clevis pins with retaining rings putting through grommets to fix
sail to mast-ends, one to affix boom to boom-bracket, and one for
telescoping junction of thick and thin mast tubes (if use telescoping
option).
~¾”
x 1/8” wooden strips for battens. About 10 feet for ~65” main batten
and ~28” outer battens. Cut length to allow slight tensioning with
nylon webbing straddling outer end of sleeve. Alternatively, fiberglass
battens from sailboard shop, cut to proper length.
7”
x 1” x 1/8” aluminum band, to be wrapped around thick portion of
mast for a boom bracket. Alternatively, 2” pipe bracket with ends
straightened and bolted through the mast if not using telescoping
option.
Approx.
1 foot square of canvas or heavier sailcloth, to reinforce corners of
sail & to hold grommets. Also optionally to reinforce batten
sleeve-ends.
Three
¾” grommets for corners (up-haul, down-haul, and outhaul).
3
foot piece of rope for boom end (outhaul).
Nylon
thread for sewing machine. I used some regular-duty, but high quality
thread and there has been no fraying.
Would
suggest making or obtaining a storage sack for the sail, like a long
ski-bag, to keep the sun off it and in case you want to put it on a car
rack.
For
outhaul cleats, one solution would be a simple pulley wheel at end of
mast, going back to a small cleat like on this web page; http://www.sailingsupply.com/Merchant2/merchant.mv?Screen=CTGY&Store_Code=2822&Category_Code=Cam+Cleats
These
cleats are designed to be screwed to a flat surface, but you could work
around that.
The
pulley wheel could be one of the blocks on this same site, like http://www.sailingsupply.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=2822&Product_Code=HK082&Category_Code=Small+Boat+Blocks
Maybe if you look around this site you can find a
block/cleat combo. that will work. You just want to avoid anything too
heavy.
*again, wait to cut pole until sail is sewn for
precise sizing.
