Iron keel rust

[sailoppopotamus]

I'm not sure I have anything authoritative to add to the discussion because I'm only 9 months into owning my first boat, but I have a similar problem that I'm about to tackle for the first time.

My plan is to sand blast the keel, then apply a coat of two-part epoxy barrier immediately before the the keel has had the chance to flash rust, fair using epoxy filler, than another 5 coats of epoxy barrier before proceeding with primer and then anti-fouling. I haven't quite made up my mind yet, but I'm considering 1-2 coats of epoxy resin on the bare keel before the first coat of epoxy barrier as some say that it will stick better to the metal than the barrier coat. Thing is, I don't have very high expectations; the keel will not be perfect at next haul out. Cast iron is surprisingly porous, so unless I leave it out to dry for months (which I'm not going to do, I want to go sailing, not watch the keel dry), whatever I do is still going to trap moisture in the keel.

 

[biscuit]

I used 121 rust-inhibitor epoxy. (EM121 EPOXY - Rust Proofing Paint) Good stuff though I made the mistake of trying one heavy coat and ended up with pinholes. If I was doing it again, I'd fair it with an unthinned coat scraped back followed by a couple of thinned coats.

After another bout of break-through rust on my iron keel, (despite using rust converters + primers), this season I have tried 4 coats of EM121.
Interestingly, as using roller can leave micro fissures. I used a brush this time and hope this will last a few seasons.

 

[WoodyP]

The big drawback with primocon is the need for multiple coats. Someone on here Seajet I think, used to recommend that the Dulux weathershield metal primer and paint worked well. I have just had some delivered as you can't find it in the local diy stores. I'm going to give it a go before anti fouling on top. What can go wrong,?

 

[Ian_Rob]

The big drawback with primocon is the need for multiple coats. Someone on here Seajet I think, used to recommend that the Dulux weathershield metal primer and paint worked well. I have just had some delivered as you can't find it in the local diy stores. I'm going to give it a go before anti fouling on top. What can go wrong,?

I have been thinking about trying Seajet’s Dulux Spec. next season and would be very interested to hear what you keel is like when you next lift. Do you haul out each winter?

 

[WoodyP]

I have been thinking about trying Seajet’s Dulux Spec. next season and would be very interested to hear what you keel is like when you next lift. Do you haul out each winter?

Yes, I generally store on the hard as we have twin keels, on a Kingfisher 30s. Because we moved and then had lockdown she came out in 2020 and has been out since then. The antifouling and primer has started coming off in places so the plan is wire brush/abrade, fertan prime and paint then antifoul on top.

 

[DanTribe]

My two pennyworth. My Stella keel was very corroded. I chipped, angle ground and wire brushed, never got to bright metal as it was a bit porous. Avoid doing this if you have neigbouring boats or cars, the rusty dust is phenomenal!
Then two coats of epoxy, I used International Epoxy Tar, no longer available on health grounds. Then two coats underwater undercoat and hard racing copper.
This lasted twenty years and was still mostly good when we sold her. Downside for a couple of years, the tar bled through and the white antifoul went pink then pale green.
A friend used builders basement waterproofing epoxy, similiar good results at half the price.

 

[Ian_Rob]

Yes, I generally store on the hard as we have twin keels, on a Kingfisher 30s. Because we moved and then had lockdown she came out in 2020 and has been out since then. The antifouling and primer has started coming off in places so the plan is wire brush/abrade, fertan prime and paint then antifoul on top.

I believe that a flap disc is better than steel wire brushing which can leave ferrous particles that can exacerbate the rusting…….

 

[WoodyP]

I believe that a flap disc is better than steel wire brushing which can leave ferrous particles that can exacerbate the rusting…….

The whole thing is ferrous, and rusts, l am only removing the worst scale not trying to get back to bright metal, which is just too much effort for me.

 

[ghostlymoron]

Galvanising is the best protection against rust but needs to completely cover the item or the rust will attack any weak spots and get underneath the zinc and spread. To do a keel you'd have to remove it and dip it.
Cold galv isn't the same thing, basically paint with zinc in it.

 

[vyv_cox]

The whole thing is ferrous, and rusts, l am only removing the worst scale not trying to get back to bright metal, which is just too much effort for me.

The effort involved is the same but worst results will be achieved with wire brushing, which drives debris into the porosity. Flap disc, angle grind or Tercoo will do the job better.

 

[WoodyP]

The effort involved is the same but worst results will be achieved with wire brushing, which drives debris into the porosity. Flap disc, angle grind or Tercoo will do the job better.

I bow to your knowledge. I hadn't come across tercoo before. It looks savage. How long will one last as they aren't cheap?

 

[ghostlymoron]

The effort involved is the same but worst results will be achieved with wire brushing, which drives debris into the porosity. Flap disc, angle grind or Tercoo will do the job better.

Hi Vyv, I haven't used a flap disc but was under the impression that they are just small flaps of abrasive material similar to sand paper. I must do more research!

 

[PabloPicasso]

+1 for Fertan. I was very sceptical but it did an excellent job

Yep, that's what I did. Probably ha e to do it every year as rust will reoccur.

 

[DoughMyDays]

Evaporust worked wonders on my lathe

 

[vyv_cox]

Hi Vyv, I haven't used a flap disc but was under the impression that they are just small flaps of abrasive material similar to sand paper. I must do more research!

I use flap discs in my angle grinder regularly. They come in a variety of grit sizes. Far more robust than the name might suggest.

 

[LONG_KEELER]

Slightly tongue in cheek, but how about Hammerite at the end of the season and anti foul at the start of the next one? ?

Just for a change I've used Flag Multipurpose metallic primer. It was £13.95 for 750ml
and has about double the solids as the others. The instructions state that it's good for underwater applications and requires one or two coats. I've used it over rust treatment. I think Primocon was about £24 for 750ml. Time will tell. I'll report back at the end of the year.

 

[Gadget257]

Does any one have preferences on the primer on a steel keel. I'm looking at VC Tar, Primocon and Hempel's Light Primer. I can't work out which is best.

 

[Spirit (of Glenans)]

International Primocon or Hemplel Underwater 3 coats. There are other primers, but they are readily available in small tins whereas others tend to be in 2.5l.

Rust on keels, when it appears, tends to need treatment every year or two. I've just finished a 5litre tin of Vinygard after using it over a period of 15 years and spanning two successive boats. I feel it was an economical buy, as I would otherwise have spent many multiples of the price on little tins of Primocon, or similar.