Best treatment for slight rust on keel?

[Tryweryn]

Hi I'm just about to anti foul a Moody 30 with a fin keel. The is just a bit of surface rust at the top and bottom of the keel. Is primer good enough to put on it and then the anti foul or with sea water do you need to treat it with better products?

 

[sailorman]

Primocon or Blakes underwater primer. R U in Ipswich

 

[Tryweryn]

How r u? No I'm in Wales now got it brought on a low loader.....smooth journey. Shes in a cradle at the moment waiting for the mast to be raised and sail drive to be done then it is in the water. I thought I would do the anti foul while i waited. I'll try what you recommended.

 

[TQA]

Best is shot blasting but a needle gun is close to remove rust .

Brush on some phosphoric acid/Naval Jelly or similar rust converter.

At least 2 coats of a zinc rich epoxy primer.

Tie coat if recommended by A/F manufacturer.

A/F.

But unless you can do this all or at least the first three steps on a warm dry day a wire brush followed by some rust converter and any old primer will be about as effective.

 

[lampshuk]

Honestly: on a Moody 30 your best bet with mild rust is to ignore it: maybe a bit of wire brush and rust-killer before priming and antifouling in the usual way then forget about it and go sailing.

Not perfect, but you'll go nuts if you start chasing mild rust patches.

 

[Lakesailor]

Beat me to it. It's out of sight. Leave it until it flakes a bit. Then treat it. It'll still rust, but you'll feel better.

 

[William_H]

Trouble with rust on a cast iron keel is that it swells and pops off the a/f paint and primer so you end up witha weedy patch. Hnece the value of grinding the rust out treat with navel jelly or similar rust converter then epoxy. The treatmet will keep the moisture out for longer. Of course if fouling is not a big problem where you are there is always next winter haul out. good luck olewill

 

[SoloMioL]

Hi I'm just about to anti foul a Moody 30 with a fin keel. The is just a bit of surface rust at the top and bottom of the keel. Is primer good enough to put on it and then the anti foul or with sea water do you need to treat it with better products?

Aww rust. Its boat cancer

(famous quote)

 

[nigelmercier]

... navel jelly ...

Gross!

 

[Laurie]

Honestly: on a Moody 30 your best bet with mild rust is to ignore it: maybe a bit of wire brush and rust-killer before priming and antifouling in the usual way then forget about it and go sailing.

Not perfect, but you'll go nuts if you start chasing mild rust patches.

+1..and of course, that bit oxidised is now sealed....(don't take that too seriously!)...but yes, wot "lampshuk" sez........

 

[KellysEye]

>But unless you can do this all or at least the first three steps on a warm dry day a wire brush followed by some rust converter and any old primer will be about as effective.

We found that a rust converter works for a time then the rust comes back. I agree with get back to bare steel and use two coats of zinc rich epoxy, as said on a dry day with little humidity, otherwise you risk flash rusting.

 

[AntarcticPilot]

We've just had our keel sand-blasted, coated with zinc-rich epoxy primer and the roughest bits faired with epoxy filler. The coating was done within an hour or so of the blasting being done.

I'll let people know how it went in a few years time! But one side of the keel had got really badly pitted; the blasting took quite a lot of material away before getting to sound metal. The guy who did it was quite puzzled as to how it had got like that - the best we could think of was that at some time she must have been moored at a place where there was a lot of electrolytic activity. It hasn't happened in recent years; there has been little sign of excessive corrosion since I've owned her.

I have heard that wire-brushing isn't always a good idea; apparently it can drive bits of wire and/or rust into the metal where they form nuclei for further corrosion.

 

[Tranona]

I'll let people know how it went in a few years time! But one side of the keel had got really badly pitted; the blasting took quite a lot of material away before getting to sound metal. The guy who did it was quite puzzled as to how it had got like that - the best we could think of was that at some time she must have been moored at a place where there was a lot of electrolytic activity. It hasn't happened in recent years; there has been little sign of excessive corrosion since I've owned her.

More likely because the keel was cast on its side and that was the top - all the rubbish and impurities rise to the top. Quite common for that to happen.

 

[AntarcticPilot]

More likely because the keel was cast on its side and that was the top - all the rubbish and impurities rise to the top. Quite common for that to happen.

Given the curved shape of the side of the keel, I doubt it would have been cast on its side - casting it in its installed orientation would make more sense. The keel is a rough aerofoil section.

 

[Tryweryn]

Thanks...It is only a very thin surface rust in one or two minor places. I just thought while i waited for the mast to go up i would treat the thing. I'll just wire brush it put some jell on, 2 coats of primer, paint it and anti foul it. Then just stick it in the water. I want to keep it in the water this winter so i'm trying to do all the jobs. Curiosity, do I antifoul a propeller?

 

[Laurie]

Thanks...It is only a very thin surface rust in one or two minor places. I just thought while i waited for the mast to go up i would treat the thing. I'll just wire brush it put some jell on, 2 coats of primer, paint it and anti foul it. Then just stick it in the water. I want to keep it in the water this winter so i'm trying to do all the jobs. Curiosity, do I antifoul a propeller?

Some don't, I do. Of what is the prop made?

 

[Dave100456]

I'm doing the same job on a restoration project where the bilge keels and centreplate are rusting and flaking. Like Antartic pilot I've noticed that one side of the lifting centreplate is much worse that the other. As its a flat plate that looks to have been machined rather than cast to the profile, it may have had more impurity on one side than the other when the plate was rolled.
I intend to grind, zinc rich primer, epoxy filler to reprofile than prime and paint. OR should I epoxy straight onto the ground steel?

 

[Searush]

Thanks...It is only a very thin surface rust in one or two minor places. I just thought while i waited for the mast to go up i would treat the thing. I'll just wire brush it put some jell on, 2 coats of primer, paint it and anti foul it. Then just stick it in the water. I want to keep it in the water this winter so i'm trying to do all the jobs. Curiosity, do I antifoul a propeller?

Probably not worth bothering with the prop unless you don't intend using it . . . Moor up in Amlwch late summer & you will kill just about anything that was trying to grow - if Parys mountain is still leaching copper residue like it has for the last few thousand years.

Surface rust is normal and not worth stressing over.

 

[KellysEye]

>I'll just wire brush it put some jell on, 2 coats of primer, paint it and anti foul it.

Please let us know when the rust comes back, exacerbated by the wire brush.

 

[oldsaltoz]

only 3 elements cause rust. Remove any one of the 3 and you have no rust.

The elements are:
Steel - water - Air.