Mast Sheaves

When I rigged the boat  in the last post I had the mast sheaves in place with some mild steel bolts as pins for them to turn on. The sheaves, which are made out of black nylon, now have some 5/16" brass pins that are held in place by 1mm thick brass cover plates. Here's a photo of the throat halyard sheave and the cover plate in the main mast.

At the top of the mainmast the peak halyard has a similar sheave, pin and cover plates. There are also hardwood lugs to support the forestay and side stays. If I was doing this again I would make the soft eyes in the wire stays a little bigger. The are a tight fit when being put in place. The good thing about this is that they won't fall off, the bad thing is that there isn't room for any leather to protect the mast and they will rub the finish off.

In the lower right the small block on a short wire strop is for the fore sail halyard (yellow rope). The cheekblock is one of a pair for the topping lift cum lazy jack lines.

At this stage I have made no provision for the topsail halyards; when/if I try a topsail I will use a cheekblock in place of one of the sheave in cover plates.

The brass cover plates for the sheave pins were cut and drilled for fixing screw on my CNC mill. For the to fit nicely against the mast they need to be curved. Holding them against the mast and hitting them with a hammer is a crude way of doing but it would damage the mast. I did this by making a curved anvil and a matching dolly out of scrap wood. Here are the three of them, each with a different radius.

These were cut using a holesaw of the right size. The brass plate placed on the concave anvil, the convex dolly placed on top and belted with a heavy hammer, result a perfect fit! It took longer to write about these plates than to make them.