Ken Frankel has been sailing on Lake Washington with crews Kim McDonald and Ondrej Lehecka. Ken has also been doing some very trick work on his mast. Check out the block that Ken made to repair his carbon mast.
The backing plate was CNC’d machined. It properly reacts to the forces from the genoa halyard that are trying to pull the sheave forward out of the mast, as well as downward along the mast. Rivets seem to be the standard approach, and this results in very concentrated loads that a carbon mast doesn’t deal with very well. In the pictured setup, the machine screws serve only to keep the sheave from falling into the mast; the screws themselves have no significant load. The metal plate distributes the forces over comparatively large areas, reducing the pressures dramatically. This is much friendlier to a carbon structure.
Ken has a whole CNC machine shop equipped to make aerospace parts. Ken would welcome other FD sailors who have projects for their boat to come to his shop to use the facility to fabricate their own specialty items.