Lazyjacks
Bill, Easy project to do. I made some for my C-30 using New England Ropes Spun Classic 3 Strand Polyester. I used 5/16", came down from above the spreaders from a strap eye on each side of the mast. Tied a figure 8 knot at the strap eye,and a bowline at the other end on both lines.Put a strap eye fore and aft under the boom towards the gooseneck and run that line through the strap eye up through each bowline and then back down under the boom toward the aft end. Here I tied a square knot and taped the ends down to the line with white rigging tape. For tension I used a small bungee cord of appropriate length hooked at the end of the boom and into the square knot. I could unhook this to slacken when sailing. Very simple system, took less than an hour to install and cost around $30 as I remember. Sorry I don't recall all the dimensions. Basically I looked at the Harken set up and figured from there. Got a lot of positive comments on it to boot. Good luck.