What I could do is use the snatch block on the rail, forward of and leading back to a turning block on the bale that Brian references. That way the snatch block is held upward and therefore does not have the awkward bending action that is likely to break it.

But I think I am leaning towards Jon's solution, which keeps things simpler insofar as only one block to worry about (being easily movable and more chafe resistant gives it an edge over the strop). I'll check that the loads on whatever blocks I get are adequate, good point Rob.

I'll also run these ideas by Win Fowler, who made the sail.

Thank you for all the discussion. I love this board.

Max