PeterWright
Well-Known Member
Hi,
11 years ago I embarked on a similar mission with our Moody 425. The keel had several coats of various antifoulings, a patchy couple of coats of gelshield, on top of some of the earlier coats of antifouling, allfinished off with the two coats of uniform antifiuling presumably applied just before we bought her. Previous experience of maintaining large bore (60", 72") cast iron cooling water (seawater) pipework in coastal power stations made me aware of a moisture and rust tolerant 2 pack epoxy primer, developed for the N Sea oil industry by a small Yorkshire firm, Corrotex, so I decided to use this. Before starting I rang the firm and was put through to their development lab.
The guy I spoke to was very helpful and recommended strongly that we clean off as much rust as possible by grit blasting and then pressure wash with fresh water to get as much of the chlorides as possible out of the pores of the casting. He recommended that we avoid grinding as that tends to drag metal over the pores, sealing in rust and chlorides. I asked specifically about Fertan and he said to avoid it as the resudual phophate would "use" the inhibitors in their primer.
Before I got round to buying the paint, 3M bought Corrotex, rebranded the paint Scotchkote 152LV and doubled the, already high, price. Nonetheless we went ahead giving the keel a light blast after the washing to clean off the gingering. We applied 3 coats of the Corrotex / Scotchkote to the keel the rudder and all the hull below the waterline, which the blasting had left with a nice matt finish for the paint to get a hold of. This serves as an epoxy shield. We finished her with Coppercoat, applied in a humidity and temperature controlled shop, which is still lasting well.
The outcome is better than I expected for cast iron which the sea has got to, but my power station experience led me to believe that we would not have major rust problems with the keel for at least a few years.
Peter.
11 years ago I embarked on a similar mission with our Moody 425. The keel had several coats of various antifoulings, a patchy couple of coats of gelshield, on top of some of the earlier coats of antifouling, allfinished off with the two coats of uniform antifiuling presumably applied just before we bought her. Previous experience of maintaining large bore (60", 72") cast iron cooling water (seawater) pipework in coastal power stations made me aware of a moisture and rust tolerant 2 pack epoxy primer, developed for the N Sea oil industry by a small Yorkshire firm, Corrotex, so I decided to use this. Before starting I rang the firm and was put through to their development lab.
The guy I spoke to was very helpful and recommended strongly that we clean off as much rust as possible by grit blasting and then pressure wash with fresh water to get as much of the chlorides as possible out of the pores of the casting. He recommended that we avoid grinding as that tends to drag metal over the pores, sealing in rust and chlorides. I asked specifically about Fertan and he said to avoid it as the resudual phophate would "use" the inhibitors in their primer.
Before I got round to buying the paint, 3M bought Corrotex, rebranded the paint Scotchkote 152LV and doubled the, already high, price. Nonetheless we went ahead giving the keel a light blast after the washing to clean off the gingering. We applied 3 coats of the Corrotex / Scotchkote to the keel the rudder and all the hull below the waterline, which the blasting had left with a nice matt finish for the paint to get a hold of. This serves as an epoxy shield. We finished her with Coppercoat, applied in a humidity and temperature controlled shop, which is still lasting well.
The outcome is better than I expected for cast iron which the sea has got to, but my power station experience led me to believe that we would not have major rust problems with the keel for at least a few years.
Peter.
