Boat Maintenance: Do It Yourself Bottom Job

If you keep a boat in saltwater year round, the bottom most be periodically cleaned and painted with toxic anti-fouling paint to discourage marine growth.

If you have a sailboat or powerboat you keep in saltwater full-time, you're going to face having to do a "bottom job" on a regular basis to keep marine growth such as barnacles, seaweed and algal slime from growing on the hull. A bottom job consists of cleaning any such growth off of the hull and the renewing the bottom paint, which is usually a specially formulated compound containing copper and other toxic chemicals which discourage marine growth. The specific type of bottom paint you use in your boating area varies and the best way to find out what works is to talk to other, more experienced boaters or especially commercial fishermen. In colder climates, you may be able to go two to three years between bottom jobs, but in areas of year-round warmth, such as south Florida or the Caribbean, you'll probably have to haul-out and do a bottom job every year. Warm water is much more conducive to marine growth.

Although many boat owners pay a boatyard to do their bottom cleaning and painting, you can save a lot of money if you do it yourself with parts from If your boat is small enough to put on a trailer, you can take it home for the bottom job. If not, you can look around for a boatyard that can haul the boat with their Travelift or crane, but will allow boat owners to work on their own boats. Not all boatyards allow do-it-yourselfers, because of insurance requirements, but it's well worth it to find one that does. This type of boatyard will take care of hauling the boat out and blocking it up on secure jackstands, then you'll be given a specified amount of time, usually a week to ten days that you can do your work before they put your boat back in the water, for an all-inclusive price. If you need more time, the yard will charge you by the day or by the month for storing your boat.

Make sure the haul out price includes pressure washing the hull as soon as the boat is lifted out of the water. This will get rid of most of the growth and it is much easier to remove it immediately than if you wait until it dries out, when it will require a chisel to get it off. Once the hull is pressure washed, blocked-up and dry, you are ready to begin sanding the old bottom paint and checking for damaged areas or blisters in the fiberglass.

If the old bottom paint is still solidly adhering to the hull, you're lucky and you can simply sand it enough to get rid of the outer, dirty layer and then paint over it. If it is peeling off, however, you will have to remove all of it before repainting the bottom.

Anti-fouling bottom paint is, by nature, extremely toxic. It has to be in order to work as intended. Sanding such paint is dangerous to your health and full body and respiratory protection is essential when working around this stuff. You will need a pair of old coveralls or a disposable Tyvek suit (found in paint stores), boots, gloves, safety glasses and a cartridge-style respirator. Don't even think about using the cheap, paper respirators sold for painting. The cartridge-type, costing about the $30.00, is the only type that is good enough for this toxic paint.

To sand the paint you will need an electric sander, preferably a random-orbital type sander using at least 6-inch sanding discs. This speeds the job up, which you will find, is highly desirable. When you get under your boat and start sanding bottom paint, you will be covered in toxic dust. The heavy protective clothing you are forced to wear to do this job will be miserable if it's summer or you are working in the tropics. You'll have to take a shower immediately after the job is done.

Once the bottom is sanded down to a layer of good, solid paint, assuming you have no blisters or other hull damage, you can then wash the hull thoroughly with water and when it dries, you are ready to apply the new anti-fouling paint. Use masking tape to mark off the waterline and then get a roller tray and strong, metal-framed roller and extension handle to apply the paint. Anti-fouling paint is heavy and hard to apply. It goes on lumpy and thick, and must be smoothed with the roller. Get it as evenly spread as possible and wait for it to dry. Follow the manufacturer's directions on the container and apply two or more coats if recommended. You won't be able to paint the areas where the jackstands support the hull until the boatyard lifts the boat in the Travelift slings. You can then touch up these spots before the boat is put back in the water.

Doing your own bottom job is hard, dirty work. It requires proper safety equipment or you will be risking your health. You can save hundreds of dollars though, maybe even more, depending on the size of your boat, and this will be an ongoing maintenance issue, so if you plan to keep a boat in the water fulltime, you should learn how to maintain the bottom.

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