Here's the lugsail. I made it for a tandem kayak in 2004 by cutting the head and foot off a nice old windsurfer sail. The design came from "sailmaker's apprentice" adapted to the shape of the original windsurf sail. I cut and hemmed it and added reef points and grommets.
The spars are all cut down from scrap sticks of 2x4 lumber. The boom jaws are made from the basket of a lacrosse stick.
We're not going to use this boom for the windsurfer, we'll use a wishbone boom instead.