Treating and protecting rusty keels

[Pauly]

Last year I aquired a nice little bilge keeler that had not had any attention for some years. It was hauled out and, amongst other jobs, the keels where cleaned back to bare metal, treated with Kurust and a few coats of hammerite before anti foul. The boat is now back in the yard and rather frustratingly the keels haven't fared well. Can anyone suggest a more durable treatment, which undoubtedly will be starting from bare metal again?

 

[sailorman]

You might try a search on the forum, there is a lot of useful info already posted

 

[Pauly]

I have had a look, but have been unable to find anything that starts from scratch, so to speak.

 

[pvb]

At the end of the day, it's primarily a cosmetic issue, rather than a structural issue. Protect them as best you can, but be prepared to do it again a few years later.

 

[VicS]

Last year I aquired a nice little bilge keeler that had not had any attention for some years. It was hauled out and, amongst other jobs, the keels where cleaned back to bare metal, treated with Kurust and a few coats of hammerite before anti foul. The boat is now back in the yard and rather frustratingly the keels haven't fared well. Can anyone suggest a more durable treatment, which undoubtedly will be starting from bare metal again?

Degease, gritblast to Sa2½, clean with solvent

1 coat Primocon thinned 10-15%, then 3 coats unthinned
OR
5 coats Interprotect.

2-3 coats antifouling

 

[pcatterall]

Degease, gritblast to Sa2½, clean with solvent

1 coat Primocon thinned 10-15%, then 3 coats unthinned
OR
5 coats Interprotect.

2-3 coats antifouling

Either follow this method and really do it well or chip off the worst and give them a good coating of paint, primer and antifoul and keep repeating as and when!! ( I used the second option and it kept the rust at bay!)

 

[Concerto]

Take back to a bare metal and treat twice with Fertan or similar rust treatment, then use 5 or more coats of Primocon and then antifoul. That system has worked for me - except on the joint of the keel to the hull. This has now been retreated and sealed with CT10 mastic before painting.

 

[rogerthebodger]

Degease, gritblast to Sa2½, clean with solvent

1 coat Primocon thinned 10-15%, then 3 coats unthinned
OR
5 coats Interprotect.

2-3 coats antifouling

This is the method I used on the hull of my steel boat and no rust below water line in 6 years. The only difference is I used 5 coats of epoxy tar before antifouling. Paint first coat within 2 hours of grit blast ( do not use sand you need a rough surface for the paint to have a proper grip.

 

[dylanwinter]

I asked the bloke who runs the yard in Aldburgh about the rust spots on the slug keels. He said just spot treat them with hammerite and live with the odd rust spot breaking though each year - or - I could just slap anti-foul on and leave them be. They will outlive me.

 

[Seajet]

I've tried all the above on my mild steel keel plate;

Hammerite was particularly useless.

I discovered Dulux Metalshield a while ago and now wouldn't dream of anything else, it's brilliant stuff and lasts far better than anything I've tried, after a season it's hardly any different from before launching.

It's one part but requires the Metalshield one part primer.

 

[theoldsalt]

I wire brush rust spots/areas (use brass nor steel brush) then treat with Kurust followed by several coats of primer. I gave up using International Primocon years ago and changed to Hempel (Blakes) Underwater Primer which gives much better results. Yes, a few spots return but usually in different places so over several years the rust has been significantly reduced.

 

[ostell]

On a boat with mild steel keel plates I steadily improved them by grinding back the suspect bits to bare metal then quickly using Hammerite primer before two coats of smooth Hammerite. Antifoul on top.

The protected area gradually grew in size over a few years. The primer seemed to be the key to the success of the process.

I believe Hammerite are now owned by Dulux so the two products may be the same thing but badge engineered.

 

[Pauly]

Thanks for all the replies chaps all very helpful. Ordinarily I would just spot treat the various areas but the rust is so widespread it will be easier to start again. Bit of a pain. Regarding grit blasting, I'm assuming that mobile equipment is available? Can it be rented or will I have to employ the services of a professional?

 

[Heckler]

I asked the bloke who runs the yard in Aldburgh about the rust spots on the slug keels. He said just spot treat them with hammerite and live with the odd rust spot breaking though each year - or - I could just slap anti-foul on and leave them be. They will outlive me.

I agree, why bother anyway, it aint going to do any harm!
I used to spot grind, bit of red primer and any old hammerite or whatever on top then antifoul.
S

 

[PeteCooper]

I asked Dulux about Dulux Metalshield having seen It recommended on here and they said it is not suitable for a marine environment.

 

[Tranona]

Thanks for all the replies chaps all very helpful. Ordinarily I would just spot treat the various areas but the rust is so widespread it will be easier to start again. Bit of a pain. Regarding grit blasting, I'm assuming that mobile equipment is available? Can it be rented or will I have to employ the services of a professional?

You can get it done professionally - not really a DIY job, but high cost if you are just doing keel(s) on one boat. Normally done at the same time as blasting the hull to remove antifouling, or if you can piggy back on another job being done in the yard at the same time.

 

[VicS]

Thanks for all the replies chaps all very helpful. Ordinarily I would just spot treat the various areas but the rust is so widespread it will be easier to start again. Bit of a pain. Regarding grit blasting, I'm assuming that mobile equipment is available? Can it be rented or will I have to employ the services of a professional?

Apologies for the "high spec" reply earlier. To which I perhaps should add "Test the prepared surface with potassium ferricyanide paper, to ensure that it is chloride free, before applying the chosen coating."
You seemed to be interested in knowing what what would give a long lasting result.

Grit blasting is as, Tranona suggests, not really a DIY job.

The alternative to grit blasting is to grind the metal surface with 24 -36 grit abrasive discs to a uniform, clean, bright appearance, using a angle grinder locally where necessary to ensure all rust and other corrosion products are removed.
This will be difficult without grinding away a lot of sound metal if the surface is pitted.


If you cannot achieve the above standards of preparation don't waste money, and time, on Interprotect epoxy primer.

I'd suggest Hammerite is reserved for the garden gate etc.
I know the coatings technologists in the group I was part of some years ago tested it in their own laboratory. They were not complimentary about its performance as a protective coating.

 

[pcatterall]

Apologies for the "high spec" reply earlier. To which I perhaps should add "Test the prepared surface with potassium ferricyanide paper, to ensure that it is chloride free, before applying the chosen coating."
You seemed to be interested in knowing what what would give a long lasting result.

Grit blasting is as, Tranona suggests, not really a DIY job.

The alternative to grit blasting is to grind the metal surface with 24 -36 grit abrasive discs to a uniform, clean, bright appearance, using a angle grinder locally where necessary to ensure all rust and other corrosion products are removed.
This will be difficult without grinding away a lot of sound metal if the surface is pitted.


If you cannot achieve the above standards of preparation don't waste money, and time, on Interprotect epoxy primer.

I'd suggest Hammerite is reserved for the garden gate etc.
I know the coatings technologists in the group I was part of some years ago tested it in their own laboratory. They were not complimentary about its performance as a protective coating.

What was that 'new type' rust remover disk which was mentioned on the forum some months ago? the video looked impressive but I can't remember where the link is.

 

[Pauly]

I've used hammerite for cars and motorbikes with a great deal of success which is why I used it in this situation. Clearly doesn't enjoy immersion. The keel surfaces are quite irregular so sanding and grinding will not be the best solution. I shall enquire about blasting at the yard tomorrow.

 

[VicS]

What was that 'new type' rust remover disk which was mentioned on the forum some months ago? the video looked impressive but I can't remember where the link is.

3M Bristle disks ?