I attachted them at the mast just below the spreaders using an eye strap. I went with a single inverted "V". Basically starting at the mast I spliced a loop in the end of the line and put the eye strap through it. Moving down that line I spliced a small block onto the end of the line about 2/3 of the way down. I run a line from the boom, through that block and back to the boom. The aft boom attachment is an eye strap that I tie the line end to with a bowline. The forward boom attachment is a small plastic cleat. I set the jacks up so that I could easily bring them forward to the mast, but I only do that when it is time for haul out. They work fine and after 17 years there is no visible chafe on the sails. I think the two sets (for the main and mizzen) cost under $50 when I built them in '97. The only hard part was splicing the small lin