How often am I supposed to wipe marine growth off the hull and keel of my moored boat?
Mark Matthews responds:
A lot depends on where your boat is moored as well as on the rate of growth. Boats in warmer waters typically see more growth, and those in colder waters typically experience less. In salt water, especially if there is a good nutrient supply, shellfish can grow rapidly. And weed and algae can grow to hull-fouling propotions in freshwater. So the right tool for the job and the frequency with which you should use it will vary as well.
In the past, I used to dive about every three weeks on my boat using a snorkel and mask and get most everything off with a scrub brush. Nowadays I hire a diver who wears a full drysuit and a scuba tank so that he can operate in the minimal visibility of my marina. It's surprisingly hard work without a tank. We are on a once-a-month schedule with the diver we use, but that is in part because there's not much bottom paint left on the boat and we live in sub-tropical zone. So the amount of paint you have on the boat, and the kind of paint it is will also be another factor in determining your cleaning schedule.
In general, the idea is to keep the growth at a minimum by way of regular wipings or brushings. If you have relatively new bottom paint on your boat, in most locales you shouldn't need to touch the bottom or keel or rudder for several months. And when you are cleaning, using a brush, scraper, or other implement to remove the growth, be careful not to remove too much paint. Of course a brush won't likely remove barnacles. If things have gone that far, you'll need a scraper. Good luck to you.