Dropping the Rudder
The rudder has damage to the bottom edge, probably from being grounded hard some time. That must have happened before I bought the boat :-)
So as a bit of a break from sanding and grinding, Adam and I dug a hole beneath the rudder, took out all the bolts and stood there as nothing happened.
The middle bracket was pretty firmly glassed in with fillets of epoxy, and we had to chisel and grind away at that to get it to begin to move, with some pretty firm taps with a lump of 2x6 timber on each side. Slowly but surely, the rudder moved downwards.
Eventually we got it all the way out and found out just how immensely heavy it is. I'd been doing some research, and expected it to be built of a stainless steel frame around the rudder stock, then infilled with wood or maybe foam, and all covered in a fibreglass skin.
The problem with this construction is that once water gets in, the wood rots and swells, and you have to cut it out and replace the core. Water together with stainless steel in an enclosed structure causes crevice corrosion, threatening the integrity of the joints between the stock and the frame and leading, eventually, to a break that lets the stock turn without moving the rudder. That's pretty catastrophic if it happens at sea.
This rudder, though, is heavier than I expected for that construction. The two of us couldn't lift it, we put it on rollers and pushed it around to a spot under the boat for a closer look. Out with the hole saw and a couple of sample cores revealed that it is solid glass fibre. That explains the weight, and is also great news, there's no rotten core, no voids to hold water and create that corrosion. The damage at the bottom is delamination, but that can be cut away and re-glassed pretty easily.
Ty Dewi looks a little odd without the big barn door rudder at the back
And, because you just have to keep going, we pretty much finished the sanding of the hull around the waterline, just a few feet left at the starboard stern.