I have been running the bottom block with the double cams off the Harkin #332 two-speed main sheet system. Use the existing triple block on the boom and just replace the lower double ratchet and double cam from Harkin. You use a double ended -- single line mainsheet and there is no confusion factor. You pull one end for fine tune and both ends for fast adjustment. This system has worked for seven years in Puget Sound and one trip to Hawaii without any problem except for wearing the cam cleats. To repair you simply buy the appropriate cam cleat and take the pieces off and rebuild both sides of the Harkin cleats.
Bob
