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How do I fix a damaged rudder?

2013 September 4

Dear Boat Doctor,

I'd like to blame the low water levels on the Great Lakes, but I think the fault lies with me. I had a little incident in the marina in spring and ended up backing into the rocks. I didn't do any real damage, other than to my pride, but I did take a little chunk out of the trailing edge of my rudder. Since it appears to just be surface damage, how do I go about fixing this?

George Stanton
Evanston, Illinois

Dear George,

Little marina mishaps happen to everyone, so don't feel too bad about it. A boat that is actively sailed will eventually get its little dents and dings, but the good news is that the problem you have is very easy to fix.

You need to start by removing the bottom paint in the area around the damage, and the easiest way to do this is with a sander and an 80-grit disk. I'd sand it back an inch or two, remove any loose fiberglass and sand the area smooth. Bottom paint is toxic, so it's a good idea to wear a particle mask. Next, wipe down the sanded area with acetone to make sure there are no surface contaminants.

You need to use a marine filler appropriate for use below the waterline. A few good choices are 3M Premium Marine Filler, which is a two-part vinylester filler, or Interlux Watertight, a two-part epoxy filler. If you like to work with two-part epoxies, you can also use West System thickened with an appropriate thickening agent. You won't need much, just enough to fill your gouge. The remaining unmixed filler has a decent shelf life and can be sealed well and saved for future repairs.

Mix the filler according to the instructions and spread it into the damaged area. Fill the area a little high and sand it back down. Be sure to pay attention to the pot life and maximum thickness detail in the filler instructions.

Once the filler cures, you will need to sand it fair. You may find that you'll need to apply a couple layers of filler to get it looking good. Once it is smooth and fair, just paint over the area with bottom paint and you should be all set. If your boat has an epoxy barrier coat, you may want to brush on a couple layers prior to the bottom paint.

Aside from the filler drying times, you're looking at just a couple hours work. And you might want to be a little more careful next time. Remember, it's always safest to go bow in to a slip where you're not totally sure of the depth.