The client wants to convert his ketch from lines left at the mast to lines led aft. His mast is keel stepped, so we couldn't attach any turning blocks to the deck. Instead, we need to build a bracket that will attach to the mast and serve as a mounting point for all the turning blocks.
The lines that will be led aft are going to be the main halyard, along with the clew and tack lines for the two reefs. Rather than bolting each of these turning blocks to the mast, I chose to make a bracket that attaches to the mast with 4 through bolts and all the related components can attach to this bracket. Each hole you make in the mast will weaken the spar. 4 through bolts will require 8 holes. If we bolted each fitting to the mast, we would be looking at 20 holes!
The mast is elliptical while the bracket is square. This is because I could not easily get a curved bracket fabricated, so instead, we had 3mm thick 316 Stainless Steel plate welded together and reinforced with 6 gussets in the corners. This makes for a pretty strong bracket, but it still doesn't attach to the mast!
I cut a template out of a file folder to match the mast contour. This template will then be used to transfer the information over at my work bench, allowing me to see how the bracket would fit around the mast without being at the clients boat. With this template, I can properly visualize where we want to place the through bolts that will hold it all together without the spar being in my view and blocking my visualization. I will be able to carefully measure and calculate the best location for the through bolts and then transfer that information back over to his boat when the time comes.
