Shelter From the Storm
The Escapist Tarp from Sea to Summit is lightweight and waterproof, and has eight tie-down points with cord adjusters to attach it securely wherever you want to set it up (say, over the boom and down around the cockpit). Or if you just want to set it up on shore for a break from the sun, a circular bar-tack at either end is an easy place to affix a rope for holding it up. Starting at $169.
Sea to Summit, seatosummit.com