Forgot to update this in a while. We had some aggro from the marina about it, which was very silly of them as people come to winter liveaboard marinas for doing boat work, and we really weren't making any mess compared to the "professionals" removing teak decks on other boats in the same marina, which they said nothing about.
Anyways, some more photos in this Mastodon thread:
https://social.tchncs.de/web/statuses/105068670817241655I've got the teak off except for the aft deck and lazarette lockers, which I decided to leave for another winter due to the marina being difficult. That section of the deck is still okay though, the forward deck was not (melting caulking and secret leaks under the deck). In terms of timing, it took me about two weeks to do half of the deck, but see below - the removal of the teak is only part of the job. My back however suffered and you have to take breaks from the oscillating multi-tool or the vibration will damage your hands.
Tools of choice were an oscillating multitool (if you can find or make a longer blade knife, do it). This was jammed under the teak edge to separate the glue from the deck and then the teak was levered off with a claw hammer. Some parts were rotting and came off easy, others had poor adhesion from new, but most were solid and came off in 5 cm wide strips (one blade length). Sometimes it was possible to pull off a plank or two intact, separating it from the teak ply underneath, which made it much easier to then remove the ply.
After that, a bunch of black PU adhesive was left. I removed the bulk of it with an angle grinder and a fine scotch-brite pad, which made quick work of it without doing much harm to the non-skid square gelcoat underneath. Then there was quite a lot of detail cleanup needed along the edges and the gaps between the non-skid sections. For this I took an hold wood chisel, ground the edges on both sides round to much the gelcoat corners and then scraped away by hand.
I kept things clean by chucking the wood into a big builders bucket and vacuuming up the black dust from grinding the glue off. I found a few more of the mystery deck holes hiding underneath, some of which had been leaking (see
this thread). I filled those in and also removed a few useless fittings while I'm at it. Luckily there are very few things bolted through the teak part of the deck, so this was not adding much work.
Then came a lot of gelcoat repairs! A lot lot lot, which are still ongoing. The holes in the patterned part were filled with thickened epoxy, ground down with a rotary tool and filled with gelcoat. The pattern is easily repaired with a small triangle diamond file (kit from Lidl), by following the existing pattern and extending it through the new gelcoat.
Also a ton of cracks along both edges where the teak had been. I suspect these were from the original mould release and just never fixed at the yard as they knew it would all be covered up with a teak deck. And the pressure washer found a lot of voids in the corners (normal from the layup process), which I also had to fill in. There was a single osmosis blister on the deck where water had been trapped under the teak and seeped into a gelcoat crack. Not a big one, so repaired with some epoxy injection and filled with more gelcoat. The areas where I've already filled, faired and polished the gelcoat look great but it's a lot of crawling around which is hard on my knees and back. I'm definitely too old to ever buy another boat with a teak deck!
Then there is the remaining black PU adhesive in the grooves of the non-skid pattern. This is impervious to chemicals. Pressure washing with high pressure/focused beam chips off the gel coat before removing the glue. It can be physically scraped out with a knife blade, but there are more grooves than stars in the universe. Various brushes did help only a little, but being rubbish PU stuff, the UV seems to be making short work of it and every time I pressure wash the deck (at regular low/medium pressure), more "white patches" appear where the glue comes off. So I expect after summer there will only be a few shaded areas where it needs removing by hand and then probably a good scrubbing with a fine brush to get it out of the deeper grooves.
Overall it's doable, but despite the initial good speed at which the wood came off, it's a ton of work with most of it being in the little details and I wouldn't recommend a teak deck to any sensible sailor