Rust on Keel

[Sailfree]

Last year I ground it off with an angle grinder, painted with Hammerite and antifouled over the hammerite.

I have noted that some prefer Fertan.

Will obviously be influenced by how it looks when boat lifted but apart from the fact the cleaner the suface the better the chance of getting rid of the rust has any one found a good reliable system for treating rusty keels that works?

 

[MoodySabre]

Nothing is permanent except perhaps epoxy. Angle grinder, vactan (like fertan) underwater primer and then AF. Just a few small patches each year. Works for me.

 

[KellysEye]

When humidity is low grind it back to bare steel then apply two coats of zinc rich epoxy paint. Do one side at a time to avoid flash rusting and the rust shouldn't return.

 

[Lakesailor]

I have two opinions.
One. It doesn't really matter.
Two. It looks worrying and nasty when you lift your boat.

Answer. Leave your boat in the water.

Hammerite is really rubbish. A zinc rich paint is your best bet. Though not that cheap.

 

[typhoonNige]

We had ours dry grit blasted 7 years ago and a rust inhibitor applied immediately thereafter. We then filled and faired and applied a couple of coats of epoxy primer. Underwater primer and antifoul on top of this and no rust 7 years later (except a little patch where SWMBO drove into a rock - my life wont be worth living if she sees this!)

 

[Twister_Ken]

except a little patch where SWMBO drove into a rock

Obviously the navigator's fault, not the helmswoman's!

 

[BarryH]

Had good results with this http://www.rocol.com/products/heavy-duty-cold-galvanising-spray Its all in the prep really no matter what you use. If cast keels you really need to grit blast or use a needle scaler.

The rocol stuff is excellent one prep has been done and its been applied. I went over the top with Flag metallic primer and the overcpated with 2 cpats of antifoul. Jobs a good'un

 

[Twister_Ken]

Think i said this on a similar thread recently.

I've used Owatrol oil on rusty wrought iron gates (close to the sea, so salt laden environment, but obviously not immersed). Worked well, and the bits Ididn't get round to overpainting are still rust free about 30 months later.

http://www.owatrol.com/index.php?langue=en&page=produits-rustol-owatrol

 

[Seajet]

Dulux Metalshield.

I've tried loads of steel treatments over the years on my keel and this is way, way ahead of the rest.

1 part but requires its' own 1 part primer.

As for Hammerite, Lakesailor is right, useless; you might as well smear on toothpaste !

 

[Vara]

Think i said this on a similar thread recently.

I've used Owatrol oil on rusty wrought iron gates (close to the sea, so salt laden environment, but obviously not immersed). Worked well, and the bits Ididn't get round to overpainting are still rust free about 30 months later.

http://www.owatrol.com/index.php?langue=en&page=produits-rustol-owatrol

Owatrol is used to protect a lot of the armoured vehicles and kit dragged out of the channel after the Normandy invasion, it seems to do an excellent job there.

What we need is a test, bit of treated mild steel, hung off a pontoon for a year.

 

[HunterWanderer]

I did mine 7 years ago now and no rust.

The keel was very bad with deep rust pockets 20 mm deep and 100 mm across. I used a 4 1/2 inch angle grinder to remove the worst rust and scale. I then pressure washed the keel and left for a couple of days to dry out.
I then painted the keel with zinc rich spray paint getting it into the big holes that I couldn't grind out.
Then run over the surface with the angle grinder again to remove the paint from the surface but leave it in the crevices.
I then applied about 5 coats of west epoxy resin. The first coat picks up a bit of zinc paint from the rust holes to prime the clean steel. Then filled the holes with car body filler and then one more coat of epoxy with white pigment.
Then antifoul over that.

Takes a long time but it has worked.

 

[oldsaltoz]

Cast Iron is not the best material, it's full of voids and contaminants when new, I have seen pockets of sand in keels.

Rotating tools like grinders spread contamination as the disc rotates, needle guns push contaminants into voids.

A grit blaster presents clean abrasive with no contamination and blasting must be to class 2 and a half, That's a silver/grey finish with no shadows.

The keel Must be as dry as you can get it because the keel will hold moisture and that will encourage rusting.

Flash rusting means just that, the surface will start to form rust within minutes of being cleaned, so it's very important to get that first coat on as soon as possible.

I actually follow the blasting nozzle with a brush or roller on an extension handle. The alternative is to blast a small area (about 1 square foot) stop blasting and coat the area then repeat. This adds to the cost as it takes more blasting time so should be avoided.

Rust inhibitors or Zinc coating will help but you must prevent any moisture getting to the keel a top coat of epoxy is essential.

The basics. to form rust only 3 elements are required. Moisture, Oxygen and Steel. eliminate any one of the three and there will be no rust.

Good luck and fair winds.

 

[rgarside]

Try looking up KBS, this has worked well on my cast iron lifting keel. Pretty easy to apply too.

http://therustshop.com/kbs-system-sa.../prod_261.html

 

[HunterWanderer]

Rotating tools like grinders spread contamination as the disc rotates, needle guns push contaminants into voids.

A grit blaster presents clean abrasive with no contamination and blasting must be to class 2 and a half, That's a silver/grey finish with no shadows.

The keel Must be as dry as you can get it because the keel will hold moisture and that will encourage rusting.

Flash rusting means just that, the surface will start to form rust within minutes of being cleaned, so it's very important to get that first coat on as soon as possible.

I actually follow the blasting nozzle with a brush or roller on an extension handle.

Rust inhibitors or Zinc coating will help but you must prevent any moisture getting to the keel a top coat of epoxy is essential.

The basics. to form rust only 3 elements are required. Moisture, Oxygen and Steel. eliminate any one of the three and there will be no rust.

Good luck and fair winds.

I dont think an angle grinder contaminates the cast iron. Any method of removing the loose rust will help.

Pressure washing removes the salt which in turn reduces the corrosion. But you're right that the keel has to be dry before any coating is applied.

You dont have to remove every spec of rust. Shot blasting is good but not really essential.
Zinc as a first coat is a must to act as an anode, and you're also right about keeping the moisture and oxygen out with epoxy.

All my opinion of course.

 

[Seajet]

The problem with epoxy coating - one of many approaches I've tried and I reckon the worst in overall results - is that the slightest chip or damage in the epoxy will lead to water getting in and being trapped against the steel.

 

[oldsaltoz]

The problem with epoxy coating - one of many approaches I've tried and I reckon the worst in overall results - is that the slightest chip or damage in the epoxy will lead to water getting in and being trapped against the steel.

So how do you keep the water away from the cast iron?
the water surrounds the keel and under pressure so hardly trapped.

 

[Seajet]

By treating it with a sensible primer and paint like metalshield; epoxy will presumably be applied to bare metal, so water trapped inside the epoxy is free to get straight at the steel...

Incidentally one has to see Metalshield to really appreciate it, it's like bullet proof !

I have had a boat with a 3/4" mild steel keel plate for 36 years, the plate was galvanised originally but this scrapes off in the keel slot over time.

I am from an engineering background and have also temped in a chandlery so reckon I know and have tried just about every steel treatment going; this did not prevent my first keel plate corroding such that I replaced it a few years ago - I think the problem with the first one was that like a lot of people I didn't initially appreciate the importance of getting the boat high enough every winter to maintain the plate.

Anyway as I say I've tried about everything so have a pretty good idea what results to expect to see when the boat comes ashore onto her high trestles in winter; Metalshield is a whole new ball game, the stuff is brilliant.

My Father is a lifelong engineer - began his career on Seafires & Hellcats, retired as top BAe crew chief on Trials Harriers - and he agrees, we've never seen anything remotely close to this stuff.

No I'm not selling it or a Dulux shareholder !

 

[oldsaltoz]

By treating it with a sensible primer and paint like metalshield; epoxy will presumably be applied to bare metal, so water trapped inside the epoxy is free to get straight at the steel...

Err No.
The keel is coated with a rust converter or/and a Zink primer before the epoxy is added. putting the epoxy on first is a no no.

Incidentally one has to see Metalshield to really appreciate it, it's like bullet proof !

I looked it up, it's a fast drying enamel, and could find no reference to it's use under water. So presumable you have no warranty either?

Anyway as I say I've tried about everything so have a pretty good idea what results to expect to see when the boat comes ashore onto her high trestles in winter; Metalshield is a whole new ball game, the stuff is brilliant.

No I'm not selling it or a Dulux shareholder !

Good luck and fair winds.

 

[Seajet]

Good luck trying a warranty on any paint or finish applied on a DIY basis !

Metalshield is made and marketed specifically as a treatment / protection for steel and alloys and does that very well ( I've also used it on an alloy rubbing strake track ) - I have never had much faith in ' rust convertors ' and the fact remains that a chipped epoxy will trap static salt water against the material.

In the case of my keel it spends half its' time dried out on a half tide mud mooring so that is the last thing I need, when I used 709 epoxy on the keel treated with Primocon that seemed to be the death knell !

 

[Twister_Ken]

Of course, when you have a lead/antimony keel, this is all just noise!:sleeping: