Real progress. Got the turning block fixed to the tabernacle:

I’ve made a (rather rough – don’t look too closely) pivot. This has threaded holes so that bolts can be screwed in from either side to avoid making a big hole in the back of the mast

With the pivot in place the mast went up!

Makes me very happy to see. I also tried it with the topmast in place – easy to lift up and fix in place – but I didn’t risk getting out of the boat for a photo. That can wait until things are more solid.
I also discovered that the main mast fits inside the boat from bow to transom:

This will make transporting easier, and raising the mast will simply require sliding it back over the transom until the pivot pins can go in. Neat!