I prefer sailing to motoring, but sometimes when running before the wind on a hot day the sun is just too hot, and the wind too light, to stay cool. I had to decide whether to motor with the "Bimini" over the boom or to continue to roast in the sun. What I wanted was an adjustable awning easily used under the boom when sailing. The common convertible top seen on powerboats didn't seem adequate since it would be difficult to stow and wouldn't overhang the sides of the cockpit like my comfortable "Bimini." I ended up designing my own awning, which gave lots of shade, was stowed quite easily and could be left up while sailing.
The awning was made of vinyl-coated Dacron which was light blue on one side and white underneath (light colors are cooler than dark ones). The Dacron fabric was used so that the awning could be set up tightly and stay that way without several battens; nylon stretches and won't hold shape. Two'/." aluminum tubes were used to stretch the awning over the cockpit. The fabric was sewn so that the sleeves holding the cross poles were longer than the poles. The flaps thus formed cut out more sun and allow rain to drip over the side. Aluminum tubing "tee" fittings from a local hardware store were attached to both poles at positions determined by the deck spacing of the support poles (I replaced the aluminum screws with stainless). Vertical support poles were attached to the deck with swivel fittings permitting fore and aft motion. These, support poles should be placed either near the toe rail or alongside the cabin or coaming so that they can lay out of the way when not in use. A 1/4" line was spliced on the outboard end of each tee fitting. Two small cleats were attached on the cabin top of the boat for these lines, although the crew usually ties them to the handrails. The aft lines have small snaphooks tied in the ends to allow quick attachment to the stern pulpit. The pressure from these lines and the fabric hold the poles together.
To set up the awning, the poles are swung up from the deck and snapped into the tee connectors, and the lines are tied to stretch the awning tight. On my boat the straight-up position is too high to allow the mainsail to be fully downhauled, and this position is used for motoring only and gives standing room for the crew. When sailing, the awning is pulled forward and thereby lower. This shades most of the cockpit but allows room aft for viewing sails or docking. When a hot sun is shining aft the awning can be swung back. I've used this awning for three summers of cruising with no problems. The awning has beaten to windward in 20 knots frequently. Sailing in the rain becomes nicer since you don't have to get wet to see or sit cramped under a small dodger. We always leave it up at night if there is a chance of rain, since it covers the entire hatch, which is left open. And best of all, when it is not wanted, the awning rolls into a compact package which stows conveniently below decks.