http://www.pearson35.com/projects/lazy_jacks.htm Used the diagram on the graph paper at this site for the design of the lazy jacks on my boat. Substituted approximately 1 1/2" diameter brass rings for the blocks. No, the brass rings don't bang on the boom. Attached the LJ's to the boom with pad eyes on each side about the middle of the boom. Probably would change that to single pad eyes on the bottom of the boom to give more space for the sail to flake down around the boom.