John
The system that Glen Ashby uses is:
40mm triple with becket on the traveller (Ronstan RF40312), up to a 40mm triple at the boom (Ronstan RF40300)with a turning block attached to it (Ronstan RF40101) then to a turning block on the boom in the middle of the boom (Ronstan RF40101) then down to a 57mm ratchet block on the tramp (Ronstan RF1720). I use this system myself and it works well. The first turning block at the top triple attaches with a twist shackle to the hook you are using to attach to the sail loop around the boom. I use a 5/16 S hook for this with the bottom arm pressed in to form a circle to hold the twist shackle and the shackle from the upper triple. That leaves a nice hook to quickly detach the sheets from the boom when returning to the beach. Thes Ronstan parts could of course easily be replace by the equivilant Harken bits. In fack I use a Harken 57mm Ratchet on the tramp (2135). For extra holding power for my old buggered elbows I also use a Harken Carbo Ratchetmatic for the last turning block in the middle of the boom. It's great when it's windy as the ratchet turns on automatically to give the extra holding power, yet it easily releases when you dump a bit of sheet. I tried the 57mm version there but it kept failing under load, so I now use the 75mm version (2680) and it's great.
Cheers
John Dowling