DocSjulle

Yes I have thought about that too, and could see some of the holes where filled with rust and painted over by the previous owner.

The test with Brunox Epoxy and Owatrol CIP showed a pretty interesting thing. It seems the Brunox is actually better at creeping under the masking tape, even though the Owatrol CIP remains wet for a lot longer time. Both products where applied in 2 coats with 6 hours between coats on the Brunox, and 24 hours between coats on the CIP.

Maybe there was a problem with the rudder stock previously, but the boat has been dry all the time we have had it. I will of course check everything anyway as I now has very access to it. The corrosion is clearly at it’s worst on the starboard aft of the cabin, and that was where the huge steel lumps of ballast where standing, and also an uninsulated heating pipe, probably causing lots of condensation.

I mostly used Tercoo rotating blaster discs for the electric drill, as that removes paint and rust pretty easy while not polishing the surface or removing base material, and leaving sort of a hammered finish. Then the needle gun (wearing earplugs under the hearing protection) for the heavy scaling on the bottom, and a chisel between the hull and stingers. My plan right now is to go over the sides again in smaller sections, and wiping with acetone and painting as I go.

Yeah I noticed that too in the photos, sometimes it hard to see anything clearly when you have been busting rust for days, with all the safety gear on and all the dust. And after a wash down more areas seem to pop up needing more attention. I actually just got 2 new Tercoo discs as the 2 other are worn out. They are expensive but really worth it for the job they do compared to a knurled wirebrush on the grinder. My plan is also to sand the sides with an orbital sander with a vacuum attached, to get some of the surface rust away just before painting, and then use the wirebrush for the last prep. The rust was much worse in the starboard aft of the cabin, so I hope the rest of the boat will be easier the deal with. At least the front cabin sides are still in a gray paint color (the parts I can under the bed).

Hmm, it sound like I’m maybe not done grinding rust 🥴 The Hempel Hempadur 15570 is suitable down to -10 degrees, it just takes longer to cure. Thx for the heads up on the soap, I didn’t know that and will have a look at the bottle.

The boat is on land for the winter and if I use a dehumidifier it should be possible to keep to steel dry. I would have liked some warmer weather but as I need to rebuild the complete cabin I have to use all the time I can get.

I think that is what I saw when I started removing the interior, big sheets of porous paint/rust that could easily be scraped of the sides. But I don’t think the required thickness was painted originally, as the paint sheets should have been thicker and more dense. You are right about the long term answers are hard to find, but it is promising that your experience with both raw epoxy and Owatrol with Danboline are fairly good. If I have the patience I might wait for my garage test to finish, before I decide what to do. The issue is that the Owatrol CIP needs a minimum of 72 hours drying time before I can put epoxy over it.

The steel is damp in the pictures because it was just washed with water for the second time. The boat is on land for the winter, and right now we have 5-7 degrees celsius and it dried pretty quickly from the first wash. I also got a dehumidifier I will be running before I start painting, and during some of the curing time. It was just a little bit of dishwashing soap in the water, and then washed down afterwards with plain water. Everything will be wiped down with acetone before painting.

Here a some pictures of the rust found.

Here are some more pictures after finishing the sides one most of the bottom. Everything has been washed down twice with water and soap, and dried of with towels. It is still damp and that it why it looks darker it really is.

Hi. This summer we bought a Dutch steel motorboat, a 40ft Pedro from 1986, because we love to spacious interior and have a dream of going sailing on the canals in Europe. It is in pretty good condition but needs some updating to the interior and electronics, and at the same time some insulation added. We decided to start with the rear cabin and have removed everything down to the bare hull. There was a good amount of flaking rust on the sides and some pretty thick scales on the bottom, but I have ultrasound tested it to still have 4mm of steel in the worst parts. So no plates will need replacing, although I might fill the deepest pits with some pad welding. I used a needle scaler and a Tercoo rotating blaster disc to remove all loose rust and paint, and have got at pretty good surface now. But am still at bit unsure how to proceed to get the best lasting paint job. I have bought some Hempel Hempadur 15570 two part epoxy primer per recommendation from the Pedro factory and a professional marine painter, and that should be possible to apply directly to the prepared steel, but I’m thinking if it might be better to use Owatrol CIP as the first layer, because it is thinner and might penetrate and seal the remaining rust better than the thick epoxy paint. I also got some Brunox Epoxy and am doing a small test in the garage at the moment. From the threads here on the forum I can see a lot of different opinions on rust converters, but I think the temperature is to low at the moment to experiment with that. The sides will be insulated with Armaflex after the painting, so I don’t think there will be problems with rust anytime soon, but the bottom is left only in paint, and although is a dry area, it will still get condensation on it. The small test I have started in the garage with the Owatrol CIP and the Brunox showed that the Owatrol smells a lot like turpentine, and the Brunox is a bit thicker and kind of converts the rust pits to black and encloses it in a sort of epoxy coating. According to Owatrol it should be fine to overcoat the CIP with two part epoxy primer and get a good bond between the two. Here are some pictures of the interior half way through the grinding job. Regards Kim