Sew it yourself! Rectangular Sail Cover Kit for Booms to 16’ lets you make your own rectangular mainsail cover. This rectangular sail cover design was popularized by J Boats and is for sails that come completely out of the track at the mast (no slugs or slides). Easy to build and quick to install, this sail cover features 46” Sunbrella^® that lays over the boom and secures with Twist-Lock fasteners. Hang down length can be reduced if needed. The length from the front of the mast to the end of the boom determines the number of feet needed.