Prepping iron keel

justsomeguy · Apr 13, 2015

Canonshooternb said:
This past season has cause some water to penetrate the surface of the iron keel on my boat. The rusted iron is on the lower portion of the keel but there are 4 or 5 spots about 6". I dont have any pictures but will take some tomorrow.
I know that i have to grind these ares down to the bare iron but how do i make a seal and prevent it from coming back is my concern.

Any input would be great

Thanks

As soon as you've ground down the spots to bare iron, apply a rust converter-type paint.

You really can't stop the rust from returning, just as you can't stop entropy. You can, however, fight it.

jibes138 · Apr 13, 2015

Get it down to bare metal then apply two coats of epoxy. Before the epoxy is fully cured apply a couple coats of barrier coat to act as a primer for bottom paint. Before the barrier coat is fully cured apply the first coat of bottom paint.

DougM · Apr 14, 2015

jibes138 said:
Get it down to bare metal then apply two coats of epoxy. Before the epoxy is fully cured apply a couple coats of barrier coat to act as a primer for bottom paint. Before the barrier coat is fully cured apply the first coat of bottom paint.

I would pass on the epoxy and after getting down to bare metal unless you have some huge craters to fill. Go to multiple coats of Interprotect 2000 as per directions followed by bottom paint while the last coat of Interprotect is tacky to,the touch. The Interprotect is essentially a 2 part epoxy anyway.

Another choice if you are just dealing with a small area is to use several coats of Primocon over the clean bare metal before applying bottom paint.

Crazy Dave Condon · Apr 14, 2015

I use to work on boats for many years as a dealer. With cast iron, wire brush the metal to get a clean shiny surface. Wipe off with acetone or alcohol. Then apply a metal primer but make sure it has or is ZINC CHROMATE to prevent the rust from reoccurring. then apply a two part epoxy filler. I use to use WATER TIGHT although expensive and a slower cure but it sure held fast and water could not penetrate it. Sand smooth and then I applied barrier coats over it to seal it.

The epoxy putty sticks did not work that well.

Richard Bryer · Apr 14, 2015

I did mine the summer before last. I had the old coatings, fairing, etc removed down to the bare metal with a needle gun---long job. Then I wire brushed with an angle grinder and a coarse twisted "bristle" type wheel. I immediately coated with a rust converting coating, then a coat of IP2000. Let dry, faired with epoxy and filler, then 4 more coats of IP2000. When I hauled out last year- after 2 months in the water there were 3 or 4 tiny spots that were ozzing rust. Let dry over winter, dremeled the little spots and filled with fairing compound. Last fall at haul out there were 3 little spots- different places, filled them with fairing compound yesterday. Anti fouling today.

Gunni · Apr 14, 2015

I have had great success on these small rust spots by simply chipping off any rust, wire brush to shiny metal, then mix and paint with marine epoxy, use a wire brush to scrub it deep into the repair. When set, I rough the surface (120grit sandpaper) and paint with bottom paint.

Warren Milberg · Apr 14, 2015

I'm not sure it's possible to completely "dry out" an iron keel and keep it from weeping and rusting in spots. I just plan on spending an hour or so each spring sanding the rust spots, applying a few coats of Interlux Primocon and then bottom painting. No big deal.

FYI, I was surprised to see that you have a Pearson 28-2 with an iron keel. Friend of mine has a 1986 Pearson 28-2 with a lead keel. Different models?

Brian S · Apr 14, 2015

Clean the cast iron as well as you can, be it sand blasting, needle gun, or grinding and wire wheels. You can also pound rust scale off with a ball peen hammer. Coat with phosphoric acid immediately to create a layer of non-rusting iron phosphate. Coat with at least 2-3 layers of coal tar epoxy (which is used on barges, buoys and the like.) Fair with a below waterline specific fairing compound. Sand, fair, sand until you are satisfied or sick of it. If you burn through the CTE while sanding, re-do the phosphoric acid and CTE in that spot. More coats of CTE over top of the fairing compound. Bottom paint.

Charlie Jones s/v Tehani · Apr 14, 2015

Brian S said:
Clean the cast iron as well as you can, be it sand blasting, needle gun, or grinding and wire wheels. You can also pound rust scale off with a ball peen hammer. Coat with phosphoric acid immediately to create a layer of non-rusting iron phosphate. Coat with at least 2-3 layers of coal tar epoxy (which is used on barges, buoys and the like.) Fair with a below waterline specific fairing compound. Sand, fair, sand until you are satisfied or sick of it. If you burn through the CTE while sanding, re-do the phosphoric acid and CTE in that spot. More coats of CTE over top of the fairing compound. Bottom paint.

Exactly