Best short term fix for iron keel

[roblpm]

My Parker 275 has an iron lift keel. Its in reasonable shape. Last year my mate did an angle grinder job on it and we did a couple of primocon coats before the antifoul.

The rust has come through quite badly.

I understand that the best way to do it is to go back to the metal and use some epoxy to seal it but I don't really have time to do that this year and i want to get the boat in soon.

So should i just do the primocon again or is there a quick way of doing something better??!!

 

[Concerto]

I would try taking it back to bare metal. Then treat with Fertan, or similar, rust treatment and then repeat. Then apply 5 or 6 coats of Primocon before applying antifouling.

Your mistake was not treating the rust and not applying sufficient Promocon.

 

[roblpm]

I would try taking it back to bare metal. Then treat with Fertan, or similar, rust treatment and then repeat. Then apply 5 or 6 coats of Primocon before applying antifouling.

Your mistake was not treating the rust and not applying sufficient Promocon.

5 minutes and some good advice. This forum is great!!

Is it right that when you take it back to bare metal you should do the rust treatment straight away??

 

[jac]

+1 for Fertan and Primocon.

Did mine last year using that. Not a sign of rust this year.

 

[roblpm]

+1 for Fertan and Primocon.

Did mine last year using that. Not a sign of rust this year.

I hope they sell it at the chandlery so i can do it tomorrow! Then again its blowing a gale outside here and raining so not looking good for work tomorrow!

 

[alahol2]

Is it right that when you take it back to bare metal you should do the rust treatment straight away??

Not necessarily, Fertan needs some rust to react with. Treat a couple of times with Fertan. Wash well. Coats of Primocon.

 

[Robin]

I would try taking it back to bare metal. Then treat with Fertan, or similar, rust treatment and then repeat. Then apply 5 or 6 coats of Primocon before applying antifouling.

Your mistake was not treating the rust and not applying sufficient Promocon.

+1, epoxy requires a perfect surface. If you grind back to bare metal it is rusting almost immediately so you almost need to be putting primocon on simultaneously. I used to use a liquid rust cleaner/killer that was wiped off after an hour with meths, then put multiple coats of primocon on and had better results than those who put a totally impervious epoxy coat onto a surface that probably still had rust going on in invisible porous bits so that it came off later in slabs of un adhered paint.

 

[Spyro]

I've used Kurust with good results as well.

 

[roblpm]

+1, epoxy requires a perfect surface. If you grind back to bare metal it is rusting almost immediately so you almost need to be putting primocon on simultaneously. I used to use a liquid rust cleaner/killer that was wiped off after an hour with meths, then put multiple coats of primocon on and had better results than those who put a totally impervious epoxy coat onto a surface that probably still had rust going on in invisible porous bits so that it came off later in slabs of un adhered paint.

Aha, interesting. Maybe i won't do that next year.

 

[Robin]

Cast iron keels vary greatly in quality. Older Westerly keels were notably porous and difficult to get sufficiently rust free to paint with anything remotely high tech. We had a W33 that we treated with multiple coats of Primocon with success but a friend with a similar boat epoxied his and it failed in slabs very quickly, but it might have been damp too from dew when he painted it. Our later owned Jeanneau Sun Legende 41 by contrast had a very smooth finished cast iron keel that we also gave the Primocon treatment to with success.

 

[roblpm]

Ok been attacking it with a wire brush on an angle grinder today. Trouble is that some of the primocon from last year has stuck really well and is very hard to get off!!!!

So is it ok to just paint the fertan over the metal bits and the occasional patch of primer??!!

Or do i really need to get to the metal?!

 

[Concerto]

Just treat the areas of bare metal with Fertan as if the primocon is really stuck, then it is working well. Do allow the Fertan to work according to the instructions and wash off with water. It will turn black. I recommend the second coat of Fertan to ensure all rust has been treated. The apply the Primocon, again as per instructions of 5+ coats.

I teated my keel last year and it is looking good except along the hull join and base of the keel, neither of which was possible to treat effectively.

 

[Daydream believer]

As to how quick you should overcoat-- In the commercial market any steel that is shot blasted normally has to be primed within 20 minutes of blasting
So as an answer to the Op question about how soon -- immediately

 

[TQA]

A needle gun does a better job than an angle grinder or a wire brush. Especially on poor quality cast iron.

Any metal prep containing phosphoric acid is good. I used Ospho.

A zinc rich two part epoxy primer worked for me. The keel MUST be warm and it MUST be low humidity for the first coat.

 

[SailingVet]

Have a look at Ferpox as an alternative to Primocon.
Worked well on our Westerly keels that had a mixture of rust, old primer, old epoxy and some stuck like glue AF.
Fertan first then Ferpox over the lot, minimal rust break through each year just needing minor retouching.

 

[KellysEye]

Having owned a steel boat rust treatments don't work the rust will come back eventually. The only way to stop rust is to get back to bare metal and use two coats of zinc rich epoxy primer. Be very careful about humidity it can cause flash rusting so only do it when the humidity is very low.