Painting an iron keel

[Cspirit]

I'm having the old antifouling professionally removed on Tuesday, weather permitting. I had originally intended to immediately paint the freshly cleaned irn fin keel, but on speaking to the very helpful person at Blakes Paints, I've been advised to firstly pressure wash the keel to remove all salt, then grind to remove resulting surface rust & then paint. The boat is 1985 Weaterly Corsair, and the chap @ Blakes takes the view that this moulding has voids & pits which need to be cleared of salt before painting. Obviosly, I want the best job, but I'm also aware that at this time of year, this could be a long process. Is it really necessary? What does the Forum think?

 

[KenMcCulloch]

Last refit I used Flag Rust Converter on my iron ballast keel, followed by a coat of underwater primer and antifoul. Lifted out today and there are one or two spots of rust but nothing like last year. Quick, easy and reasonably effective. Others will swear you need a needle descaler or grit blasting followed by two coats of epoxy. I think it comes down to how much time you want to put in.

 

[tabernacleman]

Mmm. How is the professional removing the old antifoul please? Is there evidence of rust - probably. I believe the best procedure is grit blast with an 'immediate' coating of epoxy before the iron starts to oxidise and at this time of year, unless in a heated shed, very difficult to epoxy. /forums/images/graemlins/frown.gif Even after all that, the waste metal they used in the iron keel will have so much rubbish in it that it is nearly impossible to prevent 100% , future rusting .

 

[MoodySabre]

I ground mine back, where it was showing rust, to shiny with an angle grinder and a flap wheel and then immediately gave it a coat of rust converter - I used Vactan sold through an ebay shop. Then a coat of underwater primer and then antifoul. The results the following year were excellent with just a few spots to do.

 

[AlanRD]

Keep it simple. (KISS) Two coats of Hammerite No 1 Rustproofer, then antifoul, and if you have not spent enough money send the rest to a good cause.

 

[mikejames]

I have a Westerly GK24 and it came with a rusty iron keel and osmosis 12 years ago.

I decided to ask the yard to fix the keel at the same time as the osmosis.

They shot blasted the keel , and it came out extremely pitted - I think there was one hole about 10mm deep and 50mm across. They filled the holes then used epoxy paint over the iron. 12 years on it is still smooth and it only rusts where I have removed the epoxy by stuffing the keel into Hamble Spit shingle from time to time.

The bill came to about £3000 for the osmosis and £1000 for the keel.

 

[Robin]

Well I think the man from Blakes is likely to give a better answer than Mr B. Odger on here but I'll nevertheless add my twopence worth having done the job on multiple boats over 35 years.

Firstly keels do vary enormously in quality and some castings are very porous. Our Jeanneau keel is streets ahead of the one on our last boat which was a Westerly 33 Ketch. However we did get a good job done on the Westerly keel with some effort. In our case we scraped chipped and ground off the existing, then washed it down with thinners before using a liquid rust killer (Kurust) but note that this was one without a built in primer. Excess rust killer (it only dried where activated on the rust not on bare metal) was removed with a wash of meths as instructed. We then followed that with a minimum 5 coats of International Primocon which is not an epoxy but contains a lot of aluminium I think. Primocon is easily applied and little time is needed between coats depending on temperature but we did one coat per day.

In my view epoxy may seem like it will last longer but that needs perfect conditions which rarely exist in a boatyard in winter. Firstly you need to get all the rust like the man from Blakes said and all the salt out of the voids. Then the temperatures need to be much higher than for non-epoxy paints and that doesn't mean the midday air temperatures either because the keel is a substantial lump of iron that will still remain cold hours after the air temperature has risen. Whatever the paint system, beware of painting after a cold night because there will be an invisible film of moisture condensed on the iron to which paint doesn't readily stick! Also with epoxy, you will need to be very careful with the overcoat times to get the antifoul or antifoul primer to key to it, leave it too long and it will not adhere properly, with Primocon that is not an issue at all.