centerboard repair using bondo

priceless9192 · #1 (**permalink**) 12-20-2011

I recently bought a 17 foot boat with a iron swing centerboard. The boat was sitting for many years and the centerboard was rusted up inside the boat. Upon removal I noticed large flakes of rust coming off of it, so I flaked it all off and sanded it roughly to get it back to raw iron. I am on a super tight budget and I plan to use bondo to make up the missing width. I just need advice whether this is going to work underwater. Could someone give me some guidance?

Maine Sail · #2 (**permalink**) 12-20-2011

Bondo tends to absorb water. You'd be better off with a vinylester putty or make your own mix with cabosil, milled fibers and epoxy. You could make the same cabosil/milled fibers putty with polyester resin too..

celenoglu · #3 (**permalink**) 12-20-2011

Epoy is the best product for underwater. Bondo also has a epoxy putty. I would have used epoxy + glass dust to prepeare a putty. First apply clear epoxy then use the putty.

FDR14127 · #4 (**permalink**) 12-20-2011

Bondo makes a marine product which I have used on my keel in the past. I haven't noticed anything since I applied it maybe five years ago. When I go to the yard tomorrow I will give it a look and let you know if it has changed.

Barquito · #5 (**permalink**) 12-20-2011

The missing width isn't a structural part, is it? If not, you could just paint it, and be a fraction of knot slower.

Ulladh · #6 (**permalink**) 12-20-2011

Clean off all the loose rust and paint with a rust converter.

Mar-Hyde(R) One-Step(R) Rust Converter Primer Sealer

3M also makes marine bono, and resins for other repackaged/renamed coatings.

priceless9192 · #7 (**permalink**) 12-20-2011

i think the rust converter is out of the question now that i have grinded the rust off with a few hours and a wire wheel on a drill. i will look into the bondo marine product. and no it is not structural but i would like to have it back to original size to sail fast

sfchallenger · #8 (**permalink**) 12-20-2011

Sounds like what you are looking for is a fairing compound. I'd use West Systems - they make two part epoxys with various additives to add thickness/give the product a heavier consistancy (the resin by itself is quite runny). You can apply it/work it much as you would bondo, it behaves similarly in terms of how it 'gells' when it is going off.