Tim - I just got a 1985 Nacra 5.2 and have been trying to figure out the same thing as you - the jib blocks. Like you , my tracks run up thru the tramp and then back under again. When I got it they were tied in a fixed position to the back cross beam. I have since added a line from the block to a turning block on the back cross beam and then across to a cleat on the other side, so that I can adjust the block from the windward side. But - this allows me to only really adjust them towards the stern - there is nothing so far to pull them forward if I need to - just wind pressure, and in lite winds that does't do it. If anyone gives you and idea on how to move the block both forward and aft, from the windward side, I'd love to hear it!

Dick
N 5.2 - #3002, "Cats Paw"