When we bought our first 'beginner' kayaks, they were really neat. They were made by Lifetime and were small, lightweight and best of all, they came with the sails you see in the photo. We have long since moved on to better kayaks, but we use those sails with every kayak we own including a Hobie tandem. Since we lost a sail in a near death experience, I came up with a way to make them myself. Here's how I did it
