Barnacles can be a big problem on a boat hull, reducing the speed of your boat in the water and causing you to burn more fuel to maintain cruising speed–close to 50 percent with a mere six-month buildup.

As with most things on a boat, prevention is ideal. Painting with a copper bottom-paint is perhaps the best preventative, with the copper oxide providing a toxic coating that keeps young barnacles from attaching to the hull. The key, of course, is regular bottom painting. The interval between coats of paint is determined by how fast the paint starts chipping away.

If you have attached barnacles, the solution is fixable, but laborious. Your new best friend will be a plastic putty knife. That's because scraping is an unavoidable part of the process, and you need an implement that won't scratch or gouge the surface. Your aim is to scrape off the large clumps without digging into sensitive hull surfaces.

If you haul your boat, removing barnacles immediately after pulling, when they are still alive, is relatively easy. Alternatively, if you wait until several months after hauling, you may be able to knock them off without too much difficulty.

Power washers are an invaluable aid and, if coupled with a cleaning brush to help loosen the barnacles, can do a creditable job. Care must be taken not to blister the gel coat with this method.

A boater on a recent Boat U.S. forum has found that combining both methods works well. He advises power washing first, scraping with a plastic scraper, then following up with an acid-based barnacle-removing product to remove the circles. His preference is West Marine's Ez-On Ez-Off.

For acid-based barnacle removers, brush on the solution and wait for the barnacle residue to foam and dissolve, scraping as necessary for complete removal. Clean only small areas at a time, making sure to rinse thoroughly with fresh water.

– Linda Hoff