Repainting Cal 21

Jan 8, 2015
MacGregor 26S, Goman Express 30 Kerr Reservoir
If it is VC 17 then you either have to sand it off (ugh, just did that) or use VC17.

If I just bought a boat that had VC 17 applied 10 years ago, will there still be enough left that I'll have to sand it before re-coating? The boat has been continuously in fresh water for those ten years and cleaned regularly with a brush. I intend on doing the recoat while I have it hauled to its new home.
Jan 11, 2014
Sabre 362 113 Fair Haven, NY
Take a rag dampened with Acetone and wipe the hull in a few spots. If it turns copper colored, then there is still plenty there and it will need to come off.

The problem with removing VC 17 is where the copper has built up and hardened. It becomes a solid piece of copper. In places where it is thin, like the leading edges of the keel, hull, and rudder, it comes off easily with a DA or random orbital sander.

Unless you are putting VC17 back on you will need to sand the hull, the question is how difficult it will be. I've also found that removal doesn't need to be perfect if using a solvent based bottom paint, the small amounts will just dissolve into the new bottom paint. But, too much of a good thing and the paint may well fail.
Aug 2, 2009
Catalina 315 Muskegon
If you currently have vc17 on your bottom, and you're in fresh water, the vc17 should continue to be an excellent choice. Here on Lake Michigan, it's probably the most popular paint. I've used it for many years, and I apply a thin coat every Spring and never get any buildup of paint, and it keeps the bottom clean.

Glad to hear you're thinking of doing the MaineSail program on your topsides. Should look great when you're done.

With regard to your decks, you can use the same wet sand, compound, and polish techniques up there (but not on the non-skid, of course). I did all the cabin-sides, etc., on my Catalina 28 and it looks terrific. It's just harder to do, because there's hardware in the way. Controlling the cord on your grinder/polisher becomes VERY IMPORTANT. It's easier then you may think to have the pad grab you power cord and instantly wrap itself around the tool and your thumb or fingers. For the topsides, 9" pads are good, but on the decks, 4" pads are a lot easier to get into tricky areas.

Once your topsides and non-skid deck areas are done, you can see what'll work for the nonskid. It might just be a very thorough cleaning followed by Woody Wax (not slippery). Or, you might want to consider a product like Kiwi Grip, a paint with texture that's specifically for non-skid areas. It's one-part and cleans up with soap and water.


Jun 1, 2004
Catalina 27 Mission Bay, San Diego
So to be clear the acid/toilet bowl cleaner is for removing stuck on grime below the waterline? To begin prepping for painting?
If you have brown algae anywhere.... the acid based cleaner will remove it. I've never considered it part of paint prep.... it's just a maintenance product for cleaning your boat. Just like Acetone is used to remove petroleum/rubber type marks made by dock bumpers, shoe scuffs, etc.

Again, follow the instructions provided by your paint manufacturer.


Mar 29, 2017
Jenson Cal 21 Bald Eagle State Park
Hey guys, was away for the weekend and just got the chance to check out the bottom. I cleaned a small area with acetone to check if there was VC17 but it only cleaned the remainder of the dried green slime that the pressure washer didn't get. After looking closer it almost seems like someone painted it at some point, but didn't do a great job. Although I'm not 100% sure pn that. Here are some pictures.
Jan 11, 2014
Sabre 362 113 Fair Haven, NY
The good news, the hull will come back with some elbow grease, rubbing compound, and wax. No need to paint.

Not sure if the bottom was ever painted. On an area you cleaned try some SoftScrub with bleach in it. See what happens.
Jan 11, 2014
Sabre 362 113 Fair Haven, NY
Are there a lot of pine trees near the lake? You mention the water is murky, it could be some stream run off as well as tannin. Gelcoat is slightly porous so what you may be seeing is tannin stains. If that's the case, you'll never win the battle unless you do a bottom job, sand the bottom and then put a barrier coat and bottom paint on it.