How do I Refinish My Aluminum Boom?
Q: I have my boom at home and want to strip all the oxidation off and then wax it. I can use the vibrator sander on it to get rid of all the nastiness. Now what can I do to keep it looking good. I am using fine sandpaper to keep it smooth. What do I coat it with?
Capt Al Watson, Kindred Spirit #55
The local marine store will have some special (and not so cheap) aluminum wax. I sanded and waxed my boom also. Now the boom is darker than the mast (probably from the wax), but has no corrosion.
Last year I restored the luster of my aluminum boom and spar using a buffer and some 3M Heavy Duty Rubbing Compound...the results were amazing!!!! Looked like polished chrome when I was done...but you may desire less shine in the end...I wiped everything down with a clean cloth, then followed with a carnuba wax. The finish has held up well in the weather, so far...
I have found that good old SOS pads do a great job on cleaning aluminum. I personally wouldn't use a power tool for risk of creating surface marks. After cleaning aluminum all I have ever used was wax. I would suggest you let the boom re-oxidize a bit before putting on any coating. Have you thought of how bad your mast will look after you clean the boom? Do you really want to do this project.
I have the painted mast/boom on the '91 C34 and also hide under the bimini so I don’t have to look at them. All the bubbles and galvanic corrosion look like hell. I have unscrewed all the fasteners I could, cleaned up the area and reattached using anti-seizing compound. Wish the original owner had done this as Catalina didn’t seem to use anything to isolate the SS fittings from the aluminum spars. it is particularly bad where the halyards exit the mast via the SS fittings attached with SS rivets. Your Nimble must have had better paint or something on its mast. by the way, Entropy, Inc. is what I keep thinking we should have named our company as is the best description of what we actually do me thinks...
Jack, C34 # 1169, Port Arthur, TX
Don't sand and don't strip. If you do, you will need to paint it, or seal it. Catalina's extrusions have a coating material that can easily be removed. Once removed, it will oxidize and/or corrode faster than you can spell rust! Be careful what you do to make it look good.
Bill & Jayne Quinn, C30 Illusion III #4023, Portsmouth, NH
Aluminum like copper will protect itself from further deteriation once it has a thin oxidization layer. The other thing to keep in mind that there is a process of anodizing aluminum to make it harder and less subject to pitting and the like it also darkens the color as well so it looks duller - I have heard people say that sanding the mast can remove that protective layer and you are worse off than before. I did notice that 3M makes two different aluminum polish formulas, one for anodized and one for non. One of the guys at the yard told me that if your mast isn't painted then it's the anodized kind and a little non abrasive wax will help it but don't sand or use abrasive polish. If it's painted then it's probably not and you can strip it and repaint it. I just use a little paste wax on mine.
Dave, Second Wind
Its true that the oxidation on the mast provides protection. However, you can paint it once you clean it up and probably have a lot more protection than the oxidation ever provided. Especially if you use a polyurethane paint. It is very important that the mast be properly cleaned and primed though. Check with a marine paint manufacturer for the proper process for painting a mast. When I checked into this several years ago I decided that it was more work than I wanted to do. What I do plan on doing is cleaning up my boom and then to match the natural aluminum color. Doing this to keep the aluminum stains off my mainsail.
Bob Uehlein, Menagerie C-30TRBS #2318, Charlevoix, MI
Considering how much pitting and oxidation was on my boom (1982 and always in saltwater) I think the coating was either never there or is gone by now. I sanded mine and used aluminum wax on it. So far 4 months later it is still smooth and not pitted. I can let you know in a few more years...