The resulting inch-thick piece of PVC was machined to create a luff-slot and entry aperture with a rebate for welding on its inside edge. PVC can be welded, much as steel is welded, albeit at lower temperatures. A 45 degree rebate allows the welding to be effective and produces a good looking fit on the inside, between the hatch and the boss. I used a router to machine the slots, aperture, and welding rebate and then, after the pieces were inverted and welded together, I rounded over the edges which, when the hatch was installed, were just under the hatch. I recommend cutting the piece to accommodate the deck camber first, before you relieve the top edges. I used a sabre saw with a new blade and finished the job with a rasp and sandpaper. If your router bits are sharp just a small amount of sanding will eliminate “chatter” marks. A wet-or-dry sand with 600 grit paper produces a smooth durable finish.
A 10-inch fly on the bottom of the windsail makes it easy to feed the boltrope into the slot under the hatch; the fly then is closed off with Velcro. Once the boltrope is run all the way around the hatch, and the fly has been closed, it’s easy to rotate the windsail so the opening at the top faces the apparent wind. My windsails are eight feet tall, which is high enough to feed a good supply of fresh air below. The height also keeps it well clear of random seawater on deck. Triangular flaps on either side at the top help steady it against oscillation. A light halyard running down from the spreader supports the windsail. The hatches configured to accept windsails on Flashgirl are almost directly under the spreaders. The upper part of the windsails are made from soft fabric, but the bottom part of the tube is made from a white vinyl-coated fabric that can’t be penetrated by green seawater under pressure.
Our windsails are great shipmates when we are underway and provide plenty of fresh air below. And when we are anchored at night the light down below shines up into the windsails and make them glow white. If there is any kind of breeze at all they sway gently back and forth, which is why we call them Caspers, after the cartoon ghost.
If it is raining hard you need to make some adjustments. The easiest thing to do is to rotate the wingsails so they aim downwind. Doing so creates some suction that will pull the air up from below. The air flow isn’t quite as effective as it is with the sails aimed upwind, but it works well enough in most situations.
Another nice thing about these windsails are that they are light and if you forget to adjust them during a gybe or tack, they flex rather than break. The two Caspers we carry on board have been working hard for three years and have sailed almost 9,000 miles. Although I’ve had to sew on a few patches to fix one or two chafed areas, they have been trouble free. I couldn’t ask for more.
Warwick "Commodore" Tompkins and his wife Nancy now cruise the west coast of Australia aboard their Tom Wylie-designed sloop Flashgirl.