Have you ever thought your boat’s topsides need painting? The most common answer to this question is, yes, but it costs too much.
It doesn’t need to cost a ton of money. About 95% of the entire project is sanding and fairing the hull. That means you can do most of the work yourself and, if you really want to, you can use one of the newer two-part topside paints to get a superb finish. Or, if you do the work yourself and make sure the hull is perfect, you can have the boat professionally sprayed for far less than having a boatyard do the work.
The first job is to sand the topsides back with 220 grit sandpaper on a rotary sander. (Note: Wear a respirator and Tyvek coveralls. Put elastic bands around the wrist and cuffs of the overalls.) Then fill all the dings and scratches with filler and sand every bump and mark out of the hull, taking care to remove all of the old paint.
The second sanding is accomplished with a long board (a board about four feet long) using 3M
Sanding the hull on a J22 sailboat took nearly three weeks to get rid of the old paint, fix the dings and dents, sand the hull again with a longboard, apply an undercoat, sand it lightly, then apply a topcoat.
When painting topsides, you should mask off the boat trailer, supports, bottom paint and toe-rail. Professionals put a strip of masking tape along the boot top and along the deck edge.
With this strip in place, the paper or plastic masking film can be applied. By placing the first strip on the hull, you can get it perfectly straight without having to bother with the masking paper or film. The edge of the masking paper is then taped to the first straight tape. Remember to press the edge of the tape down carefully to prevent paint from going under the tape edges.
If you plan to spray your hull, protect the hull bottom, trailer or supports and rudder. You should also cover the entire deck. Overspray gets everywhere and the only way to prevent problems is to cover everything.
Wipe Down With a Solvent
When you have finished sanding you need to wipe the entire hull with a solvent to remove sanding residues, any grease or oil that might be on the surface and prepare the hull ready for paint.
You should use a solvent recommended by the paint manufacturer to be sure that solvent and paint are compatible. When wiping down with a solvent wear full protection to keep solvent off your skin. Also, remember not to put your hands or fingers on the hull. The oils from your skin can cause problems in the paint layer.
The next job is to paint the boat. You can spray or you can brush paint the hull. Brush painting takes longer, but you get a thicker coat of paint. If you spray, you may have to apply two or three coats of paint.
You should prime the hull with an undercoat, especially if the topside paint is a different color than the original paint. For example, if you hull is white and you plan to spray it dark blue, you might sand, then apply a grey or dark blue primer before applying the topcoat. Most primers are grey but you can get colored primers. Remember too, darker colors tend to heat up more in the tropics and degrade the paint layer faster or allow ‘print through’ to show after a few years.
Brush painting is all about technique. Mix and apply the paint according to the manufacturer’s instructions. Some manufacturers recommend a sponge brush while other recommend a hair brush. Do not thin the paint too much when brush painting or it will run. Apply a small amount of paint at a time. I find an area from the toe-rail to boot top of about three feet to be the easiest to work with. For best results always keep a wet edge on the paint layer.
Apply the first strokes of paint horizontally to cover the surface, then gently stroke the brush from toe-rail to boot top, ideally, applying the brush on the toe-rail masking tape and lifting the brush off the job on the boot top masking tape. This prevents a mark from showing where you lifted the brush off the job. Work from forward to aft making sure you get full coverage. Check frequently to be sure you are not applying too much paint and getting runs. Most of the latest paints will settle and fill brush strokes as you work, but you will need to be sure you do not get any runs.
There are two main methods of spraying paint. The first is the conventional high-pressure spray, which tends to put a lot of paint in the air as well as on the boat. The second is low-pressure high-volume (LPHV), where a lower air pressure is used, and a higher volume of paint is applied. First, check to be sure your paint can be applied using the method that you desire. Some paints tend to clog the spray gun when used in LPHV systems.
You will need to protect yourself when spaying. Mask off the entire boat and wear a Tyvek suit, respirator, goggles, rubber gloves and bootees. Put elastic bands around wrist and ankles to prevent overspray from going up your sleeves and legs.
When you spray, work from side to side or from top to bottom starting the spray on the masking tape and lifting it off on the masking tape. Do not pause the spray as you work or you will build up a lot of paint and end up with drips and runs. Typically, you will need two or more coats of paint when spraying to be sure the paint layer is thick enough.
Roger Marshall has written 14 boating related books including his latest, Fiberglass Repair Illustrated.