i sail on chartered yachts and would like to make or purchase a running backstay system. most of the yachts do not have them. some of the boats have split backstay. i know how i would make one for the split backstay but i am not familiar with the hardware. i would need two blocks that i can attach without removing the backstays. can anybody tell me what these blocks are called? is there a way to tension a single backstay using a home made rig?