You cover your main sail, but what about your headsail? In the Pacific Northwest, it is not just UV that will damage your furled headsail; it is also the rain and air born pollutants. Extended periods of moisture, in combination with dirt and other contaminates can lead to mildew, algae and even premature structural failure of your sails, particularly laminates.
Extend the life of your sail with a headsail sock. Easy to hoist - they not only block UV in the summer, but shed water and contaminates in the winter. Ullman headsail socks are made from Sunbrella fabric to withstand the elements, and use an effective diamond lacing system that draws the sock tight against the furled headsail to reduce flogging. Be kind to your sails on a cold winter night, call your Ullman rep and ask how you can protect your sails from old man Winter. The headsail sock from Ullman Sails is $13.50 a foot up to 50' luffs and $17.00 a foot up to 75' luffs. They come in all Sunbrella colors.