Rust on Keel - how to proceed?

[Dougtiff]

My experience with iron bolt on keels are as follows, have not run into a STEEL cast keel,most likely its CAST IRON or LEAD, if lead it will not rust, but cast iron will,it will have moisture in it and there is nothing to be done about, it cannot be dried out, you can barrier coat it with epoxy or any of the many two part coverings, but the moisture will gravitate out and the rust will show up again, save alot of money and labor and just clean and paint with bottom paint, when you do the bottom.

[Pete7]

If it was just the cast iron keel then I would agree, but this looks like someone has ladled filler on both keel and hull, then not even bothered to sand it down. What is that covering up would be my question? Angle grinder and wide cold chisel needed here.

I have a pair of cast iron keels, they are patch painted each year as the rust comes through. Grind down, 4 or 5 layers of Primocon and then antifoul paint. Occasionally it it gets really bad then I take all the paint of on side and start again. As Doug says, the cast iron will have water and salt in it, so epoxy will come off again eventually, but that piece of cast iron, well it will be around long after I have departed this planet.

[Scaramanga F25]

That cross-checking is probably bondo or an epoxy compound that has flexed and is below the keel-hull line. It was possibly an effort in fairing.
On one joint I inserted an 1/8 inch string in the cleaned out joint and keel. I
then faired the joint. But before the compound hardened I carefully removed the string leaving a gap that when the fairing epoxy cured I filled with 5200. That way the hull could flex a little withought cracking the fairing compound.

[chowdan]

I would say based on my experience, get the hull sand/soda blasted then open up that joint and go from there.

Definitely an iron keel, which your going to want to grind down any area that has rust. If you leave the rust and don't go down to good material, any repair you do will eventually fail as the iron will continue to expand due to rust.

It will be a messy job, but doing the sand blasting will save you a TON of time. You'll then only have to take down the gelcoat and any bondo that exists.

My sailboat had the C&C smile. I ground down to raw glass and lead on both sides of the joint for a total width of 8". If i did it again I probably would have done 12" in total just for added security, but 8" is totally fine.

I filled the gap with 3M 4200 and then tightened the bolts before it cured. Once done, I laid up 6-10 layers of glass across the entire keel joint(8" wide). I then used West Systems 407 as a thickening agent to fair out the repair. Then used Interlux 2000e as my barrier coat and did something like 10 coats(due to over buying).

If you go this route, I would say the only thing I would have done was after my final fairing with WS 407, I would have slapped a coat of Interlux 2000 on to identify any uneven surfaces and before it cured would have put a final layer of thickened epoxy to make it perfectly fair. Having the grey contrast from the barrier coat really showed how NOT perfectly fair the repair was, but I was out of time and had to sand and repaint the entire hull before splashing in a few days.

It's been 6 months since my repair and I have yet to see any cracks in the repair. I am fairly confident in the repair, but if I actually make it down to a place like Mexico(hopefully 2021), I am going to haul out, sandblast the hull and drop the keel and redo the keel stub compound for sanity sakes(boat is 39 years old).

If you need something that flexs, look into West Systems G-flex product.

[LiveCat6]

Thanks so much everyone for the detailed responses. I really appreciate your time.

Down the rabbit hole I go, it seems.

I purchased her last year for $5500, trying to walk that fine line between taking reasonable care of her and making her last, and not going nuts with all the nice things I could do....

That being said, the answer seems to be to get it soda blasted down and then see what's going on under there. I'll have to ask around and see if I can get that done without paying an arm and a leg.

I'll return with updates and photos as work progresses, and I'll re-post this on the CS 27 forums as suggested. Thanks guys.

[chowdan]

Originally Posted by LiveCat6

Thanks so much everyone for the detailed responses. I really appreciate your time.

Down the rabbit hole I go, it seems.

I purchased her last year for $5500, trying to walk that fine line between taking reasonable care of her and making her last, and not going nuts with all the nice things I could do....

That being said, the answer seems to be to get it soda blasted down and then see what's going on under there. I'll have to ask around and see if I can get that done without paying an arm and a leg.

I'll return with updates and photos as work progresses, and I'll re-post this on the CS 27 forums as suggested. Thanks guys.

I understand that fine line. I also try to follow a similar line.

My view is spend the money in the areas that make her reliable, and safe and to do things right from the start.

All other things - creature comforts - are secondary expenses that can come after the primary repairs are brought up to snuff.

Best of luck and keep us update!