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Saturday, May 27, 2017

Rudder and Hull

Finally got to sneak off from work a little early after trying to do that all week. Decided that the rudder would take way too much sanding so took a few thin passes with the planer to get down towards the resin, should be good to epoxy coat after a bit of sanding now, once the bottom is rebuilt. Looks a bit like a crazy piece of modern art right now

Kept going with the hull blisters, almost done, and we mixed up a little epoxy putty and testing techniques for filling them, which looks like it should be a fairly straightforward job.

And helped Kevin finish off the canoe repair, which is looking good and a nice test of fibreglassing skills.

Sunday, May 14, 2017

Still sanding, and work inside

Still working away at sanding and grinding. Getting there. 

Been taking down all the headlining sections inside, so we can see all the fittings and fixings coming through the deck, identify the places where we've got leakes, release the hardware for when the deck comes off and have access for any new wiring. The headlining is trimmed with hundreds of carefully cut pieces of teak, so they all get mapped out, removed and labelled. Max is great help for this sort of thing.

Sunday, May 07, 2017

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. 

Monday, May 01, 2017

Find'em and Grind'em

Dusty work this weekend, continuing to prepare the hull for the epoxy bottom treatment I'm using (Coppercoat). The boat has a mild case of osmosis - leftover chemicals from the manufacturing process react very slowly with moisture to form bubbles, or blisters, just below the surface of the hull.

At this level, in a hull an inch thick, it's pretty much cosmetic and we've happily left it for ten years. But the slow bulging of the surface can force the coating to flake and separate. Since we're going to a lot of effort and expense with the Coppercoat, it makes sense to fix as much of this as possible.

That means locating the blisters and grinding them back to solid fibreglass, then letting the hull dry out through the summer and filling them in with epoxy filler in August.

The first photo shows the white spots that reveal the blisters - white because there's a thin unbonded gap between the surface layer and the resin beneath. The black is paint that hasn't been fully sanded off yet.

In the second photo, I've ground out the blister until we are back at solid laminate, and marked each one so we know where to go with the filler later. It's a dusty job, I've got a respirator, goggles, ear muffs and look more like I belong in a Doctor Who episode.

Blisters show as white spots
Grind out each one and mark for filling

While I have the sander, grinder, scaffold and protective gear all set up, I've also been getting rid of the last of the paint around the waterline. It's slow work but finally showing a real difference. Before...and after

Before sanding the waterline

Down to bare hull

And between the sanding, usually when the rain showers came through, I moved along a couple of other looming tasks. More cleaning and scraping of the bilge area around the stern gland - this is actually getting fairly close to being paintable, even though it hardly looks that way.

And decided to go looking for the chainplates - the steelwork that holds the mast up. These are original and almost certainly in need of replacement, inspection at the very least. The bad news, well known with these older boats, is that the builders set them into the hull and completely covered them in fibreglass. 

I cut away the back of a kitchen cupboard to check on this and sure enough - there it is, a tell tale large bulge of glass fibre covering the chainplate. Well, time to research and then get busy slicing it all out. This is a tough job. 

I've found a couple of good reference sites from people who've done a similar task: