Iron Keel Epoxy Coating Problems

[01kiwijohn]

Had the bottom and keel done at the same time. It was done by a well known boatyard in the south Puget Sound. It has performed well for 5 years and was in perfect condition when I re-painted the bottom 2 years ago. This winter, I hauled it and stored it on shore, in SE Alaska. Two weeks ago, the yard sent me these pictures. Anyone else had such a problem, or have experience with this?

[Benz]

Could it be that the keel shrank with the cold, causing the brittle epoxy to crack?

[Dymaxion]

Oh oh, just about to have my cast iron keel sandblasted professionally, then I'll epoxy it. I also haul out each fall and we get -20C temps over winter. Where has the "paint" delamination occurred? Is that the bare iron exposed, not much rust apparent if so, or is it the antifouling lifting off the epoxy? Do you know brands of paint used, by Puget Sound yard and yourself? Maybe an incompatibility issue? Prep issue? Tx

[dougweibel]

It looks similar enough to a problem we had with stray current corrosion that I would be sure to check things out closely with a reference cell once the boat gets back in the water. You can buy one online or have a pro do it.

https://www.boatzincs.com/corrosion-...electrode.html

[Sail Away 3]

I guess I am not the only one. Cast iron seems to be an issue. Back in 2008 I sandblasted my own keel and coated it with Interprotect 2000, 5 coats. Sand a section then immediately coat with the epoxy and move on to the next section. until the entire keel was coated. Then added 4 more coats. That lasted, withstood 6 years of ocean sailing with a few grounding damages until 2017/18. Spring 2019 I again sand blasted the keel and this time used a zinc based paint and am not happy with the performance of it and may have to redo again this fall should we ever get out of quarantine and able to sail again this year. Several spots of rust are forming under the coatings.

[Sail Away 3]

Originally Posted by 01kiwijohn

Had the bottom and keel done at the same time. It was done by a well known boatyard in the south Puget Sound. It has performed well for 5 years and was in perfect condition when I re-painted the bottom 2 years ago. This winter, I hauled it and stored it on shore, in SE Alaska. Two weeks ago, the yard sent me these pictures. Anyone else had such a problem, or have experience with this?

Looks like antifouling over Interprotect with rust possible under the Interprotect, Maybe VC 17 bottom paint???
Is antifouling flaking off the Interprotect?
Is the epoxy still attached good to the cast?
How bad is the rust under the epoxy?
Determine what your future plans are.

I am very interested to know as I will be redoing my keel at some point soon.
Ken

[Don Sloma]

In twenty years, I've had good, bad and indifferent epoxy jobs on my keel. None held up more than a few years without at least a couple of small rust spots. My personal best was six years between complete redos. One experienced Beneteau owner told me he just sands, epoxies and repaints rust spots at each haul out. He hauls out every two years.

[Scaramanga F25]

I have had only one iron keel and did the back to iron and quickly cover with coal tar epoxy and then many coats of epoxy to some disappointments 2-3 years later.
I hate to say this but I observed over a few years that other YC members with iron keels were having better luck with several coats of "Rustoleum" painted on. Touch up in the spring.

[01kiwijohn]

Originally Posted by Benz

Could it be that the keel shrank with the cold, causing the brittle epoxy to crack?

Don't know. That's why I put it out there.

[01kiwijohn]

Originally Posted by Dymaxion

Oh oh, just about to have my cast iron keel sandblasted professionally, then I'll epoxy it. I also haul out each fall and we get -20C temps over winter. Where has the "paint" delamination occurred? Is that the bare iron exposed, not much rust apparent if so, or is it the antifouling lifting off the epoxy? Do you know brands of paint used, by Puget Sound yard and yourself? Maybe an incompatibility issue? Prep issue? Tx

The yard claims they used Pettit Rustlock, then Interlux 2000-2001, with micron 66 bottom paint. How they stripped the keel I don't know. I did see it, as bare metal, just after they did it but I was on my way out of town, on business, and didn't get to study the method used.

The failed bond is between the metal and the epoxy; the bottom paint, as you can see, is still adhering quite well.
I have a local surveyor inspecting it now so will try and remember to update this post after his report.

[s/v Jedi]

I would try a specialized primer next time, to go between the keel and the epoxy. I would look into POR-15 and Awlgrip CF Washprimer. Maybe even coaltar-epoxy.

Edit: on my lead keel I used epoxy that I sanded into the lead while the epoxy is still wet (so that no oxygen gets to it).

[01kiwijohn]

Originally Posted by dougweibel

It looks similar enough to a problem we had with stray current corrosion that I would be sure to check things out closely with a reference cell once the boat gets back in the water. You can buy one online or have a pro do it.

https://www.boatzincs.com/corrosion-...electrode.html

Don't think so. We normally keep the boat at a marina, in Tacoma, and the problem didn't show up there. This year, we spent about 85 nights on the hook, over 3 1/2 months, then hauled and stored it ashore. That's when the problem began.

[Sail Away 3]

[QUOTE=s/v Jedi;3124804]I would try a specialized primer next time, to go between the keel and the epoxy. I would look into POR-15 and Awlgrip CF Washprimer. Maybe even coaltar-epoxy.

A number of our shark sailors use a POR type chemical that I may try, though I still have a good bit of my zinc based paint leftover which I may use up first.

[Clivevon]

Right. Coating Cast iron keels is a real known problem. You need a barrier coat on first before the epoxy. I had this done some years ago. Cant remember the details but seem to recall something about ceramic beads?? If still stuck i could dig back Through my records to see if i can find What they used. 6 years ago & all ok so far...

[FULLCIRCLE331]

I have a 2005 Beneteau with a cast iron keel. Every year I have to repair spots in the spring. They only show up after setting on the hard for a couple months. I carefully grind to clean and repair with interprotect 2000. Never had to sandblast. A tip with interprotect. If I have material left over I keep it in the freezer and can use it a week later.

Many years ago I had a cast iron keel that I sandblasted and epoxied and embedded fiber glass cloth in the second coat then added two more coat. This was a two part epoxy, before interprotect. It lasted 20 years with no problem until I sold the boat.