Cockpit covers are designed to reduce wind turbulence when driving with your kayak on the roof - reducing fuel consumption. They are also intended to keep out the creepy crawlies and windblown sand when you are in camp.
When driving, we use a length of bungee & olive clip to hold onto the cockpit cover loop - just in case!
For more information see our page on Spray Decks, Cockpit covers and Sundecks on our East Coast Kayaking site.