Iron ballast keel refinishing

[KAIROS]

I'll be grinding and chipping rust from the keel soon and am figuring how to refinish it. Sandblasting is not an option.

When I get it pretty well cleaned up I want to apply a primer compatible with bottom paint. I don't believe that any finish applied to iron below the waterline will last long....unless you could blast it down to clean iron first.

The iron will rust under epoxy, and then future refinishing would be more painful. So, I want a system that is simple and easy to re-do every couple/few years.

The options that come to mind are: (1) using OSPHO or similar substance which makes rust inert, then priming over it; (2) use Hammerite or similar paint which handles rust well; (3) use a high zinc primer or paint like DevConZ or Petit zinc chromate primer.

How do you take care of your iron ballast keel?

[Ken Hutchins]

Use the search gizmo I did conprehensive post about treating CI keels.

[Don Z.]

What we did on a Rhodes 19 this year was:
Chip rust with a hammer... then wire brush... then phosphoric/muritic acid. The acid neutralized any rust in the pits. Then there were several coats of interprotect 2000...

[mike hanyi]

then put a big zinc on the thing to slow down the rust.

sandblasting and epoxypaint is the only thing that will work other then hot dip galvanizing the thing.

[Oyvind Snibsoer]

The ONLY coating that is non-permeable to water is coal tar epoxy, which can be had in any color as long as it's black. There are also concerns about its toxicity, but this relates mostly to long-time exposure, and it has a nasty tendency to bleed through any top coating. The latter shouldn't be much of a concern for a keel, though?

[Concordia...41]

I'm right in the middle of the same research and will make time to post tonight when I get home.

As Ken stated, he did a long post on this. If someone could bring that up and add it here that would be helpful for many folks.

I also have some 2001 stuff from thechemist I printed and just came across as well as my current research on coal tar, Creame Kote [sp?] recommended by Triad Boatworks, and something called Amerlock [sp? - sorry notes at home] recommended by a local yard.

Bottom line = lots of work :) ;)

[KAIROS]

Concordia, we seem to be on parallel courses recently.

I am suspicious of the coal tar epoxy, epoxy, and other forever options. These are not completely imprevious materials. They work for a long time, but when moisture does get in, the corrosion rate is greater....when the finish is removed there might be more deep pitting. And, removing the finish might be a horrendous job......probably impossible without sand-blasting.

I had a centerboard boat with an iron board. Over the years I tried various finishes including epoxy. In the end it seemed simplest to grind/wire it down every few years to get most of the rust off, prime it with OSPHO, and paint it with bottom paint.

That was 15 years ago though.....maybe there's something nearly as simple yet longer lasting now?

[KAIROS]

......I simply hit it with 2 coats of Sub- Paint, then bottom paint. So far, so good, (1 year later) and much better than plain bottom paint.

Hey, what is this 'Sub- Paint'? Does it go under other paint and ping?:D

I expect it's some milspec stuff. Is there a way us civilians can get it?

Thanks Brian.

[willmarsh3]

What I would do today is wire brush to get must of the rust off. Then ospho. Paint with epoxy. Drill and tap a hole to screw on a piece of zinc. Finally use Trilux bottom paint that contains copper thiocyanate. Each year the rust will probably be minimal.

Here's the reasoning:

I had a Catalina 25 with a steel or iron swing keel that weighs 1500 lbs. I sailed her in the Chesapeake out of Deale, MD. This water is brackish.

The rust on the keel looked horrid. But when one considered that it weighed 1500 lbs and was probably solid iron throughout it was actually quite insignificant. It would probably take longer than the life of the boat to rust apart.

Nonetheless, I tried various things each haul out including wire brushing and painting with Rustlok. This didn't help much. Then I drilled and tapped a hole and screwed on a small zinc. After the boat was in the water for about 9 months most of the zinc was gone. And the rust seemed to be that much less severe. I figured that the rust was slowed down enough that the keel would not lose more than 1 or 2 percent of its mass over the life of the boat.

I recall the manual for the boat advising use of rustoleum spray paint in addition to screwing on a zinc.

Another thing that I think accelerates the rust is use of bottom paint containing particles of copper or copper oxide. Copper is much higher on the galvanic scale than iron or steel so it will accelerate pitting and rusting wherever it touches the iron or steel. Use of something such as Trilux which has copper thiocyanate avoids this problem.

I think these will reduce the rusting to a level that obviate the need for sandblasting or lots of maintenance.
But if you still want to do that then the Metal Boat Society may be able to help you. My understanding is that there are a lot of steel boats in the Puget Sound area. These require sandblasting so there are probably a number of yards that do that nearby. One guy I talked to in 2003 said there was a yard up in BC that allowed DIY sandblasting.

Good luck

[Bob Cleek]

"...then put a big zinc on the thing to slow down the rust."

NOT!

You'd need the mother of all zincs to accomplish anything, and that would be at the expense of all your higher metals. God, there is nothing worse than over-zincing. Don't do it!

Fact is, there isn't much you can do about ballast keel rust. The rust does nothing but look bad. The ballast keel will outlast everything else on the boat, so it's no loss anyway.

You can chip it, or blast it or wire-wheel it on a heavy hand-held grinder motor (which is how I came to kneecap myself with a running wire wheel once!) Then you can fill the divots with epoxy or whatever and smooth it out and then paint with epoxy or whatever else you have and then bottom paint over that.

The next time you haul, there will be more rust... maybe less, but rust nonetheless. Learn to live with it.

BTW, not only did the "Paint Fairy" die, but Mare Island NSY, like Hunter's Point NSY, itself is no more, thanks to the Base Realignment and Closure Program. Pretty stupid of the government to close every damn naval shipyard in the best natural harbor on the West Coast, but they did. Bremerton, WA, is all that's left, with subsidiary repair bases at San Diego and Pearl Harbor, I believe.

When it was going, Mare Island was a real resource for "surplus" boat supplies. Lots and lots of guys worked there and it wasn't hard to get what you needed if you knew somebody. Back in the '70's when it was a nuclear sub base, there was a LOT of that sub paint around. It used to be a vinyl base, and later epoxy. It really worked great and the price was right. Because there weren't any EPA restrictions on the stuff, it really killed everything. Nobody really knew if it was "surplus" or "rip off," but we followed the military policy of "Don't ask - Don't tell." There doesn't seem to be so much of it around anymore. It would be interesting to trace down the real story about that sub paint. Of course, it only came in one color, black. I expect that it also was designed to deter sonar "pings," since it was always sort of thick and rubbery.