Time to paint your boat's topsides or deck? Here's how to get professional results everytime.

By Paul Noack

When sanding, compounding, using a color restorer, then waxing or polishing fails to restore the color and gloss of your boat's topsides, consider applying paint. Painting your boat's topsides will greatly increase its appearance and value. With quality paint and the proper techniques, you can easily achieve a professional-looking finish.

Painting a boat is time consuming but it has to be one of the most gratifying jobs you'll do on your boat. It's like washing your car by hand you will know where all the imperfections are but when you step back you won't see them.

Yacht Paint Development Historically, boat owners have always sought the perfect topside finish, desiring color brilliance, gloss and durability. For many years, pigmented varnishes were the only enamels available. They were relatively easy to apply and required no professional knowledge. However, they were limited in gloss and durability.

Alkyd enamels came next. These offered longer-lasting protection but lacked the desired ease of application and gloss. These paints were then modified with silicone and/or polyurethane, which offered better water resistance and shorter drying time, but sacrificed gloss and color retention. They were also difficult to apply.

To overcome some of these drawbacks, two-part polyurethanes were developed. Composed of a base and reactor, when mixed, the result is a chemically-cured paint film with superior gloss, keener color and an extremely durable finish. Most recently, single-part polyurethane technology has evolved to produce superior gloss and lasting performance that's similar to two-part polyurethanes but with the application ease of conventional enamel. Today's technology offers you a choice of both one- and two-part polyurethanes.

Single-part paints will last three to seven years and two-part paints between five to nine years. The longevity of the paint depends on where your boat is kept: the finish on boats in southern climates where the sun is more intense will not last as long as those finishes in northern regions.

Materials Two-part polyurethane paints (i.e. Awl Grip, Interlux Interthane Plus, Interspray, Sterling) would be an excellent choice for topsides, decks, aluminum masts or any area above the waterline where a durable, high-gloss or abrasion-resistant finish is required. Two-part polyurethane is the finest all-around coating that can be applied by brush and roller, but it can also be sprayed with the proper safety equipment. Two-part polyurethanes must be thinned out quite dramatically with the manufacturer's specified thinner. It's important never to mix different manufacturer's products. Two-part paints should never be put over single-part paints or primers as the solvents will attack the single-part paint causing poor adhesion.

Single-part polyurethanes (i.e. Interlux Brightside, Pettit Easypoxy, Sikkens Polyester Yacht Paint) have built-in self-leveling characteristics as well as incredible abrasion and chemical resistance. Some manufacturers are also adding Teflon for better dirt and abrasion resistance. These paints are the most popular paint for the first-time user.

Alkyd-based enamels (i.e. Interlux Yacht Enamel, Pettit Shipendec, Sikkens Super Gloss) have been around for more than 40 years and have a loyal following with wooden-boat owners. These paints tend to go on thicker than polyurethanes, have great hiding attributes and last about three to five years.

Thinners are added in order to get proper flow of the paint. Paint manufacturers will have a suggested thinner based on the paint you are using and whether you are brushing and rolling or spraying the paint. The amount of thinner needed varies between 5% to 55% and it's wise not to stray away from the manufacturer's suggested quantity.

Safety

Polyurethane paints contain isocyanates, which contain VOCs (Volatile Organic Compounds), and I cannot stress enough how important it is to wear the proper safety items. These include thick rubber gloves, goggles, safety glasses or other eye protection, long sleeve shirt and pants (tape the cuffs) and a respirator rated for toxic fumes (see "The Air You Breathe"), and when spraying, a vapor-tight suit and use supplied air check the laws regarding VOCs for your part of the country. Always read the precautionary statements on the container labels before using. Work in a well-ventilated area and observe all warnings. Solvents contain hazardous chemicals that can be absorbed through your skin so use them only in painting, not for washing your hands.

Surface Preparation Painting a boat is not difficult. By purchasing quality marine paints from well-known companies, you are assured of great results as long as you follow the manufacturer's instructions. Some companies supply a Boater's Painting Guide free of charge.

Topside paints should never be used on parts of the boat which will be submersed in water for long periods of time; the paint will blister if this happens. It's best to divide your boat into two parts: above the waterline, which this article deals with, and below the waterline. Topside paints can be used on any surface (wood, metal, epoxy, gelcoat) as long as the surface is prepared properly. It's said that preparation is 99% of a successful job, and it's true. Before you start, it will help to build a scaffold around your boat to ensure easy access to the boat and to allow you to apply the paint without any interruptions or delays.

If your boat has previously been painted and you are unsure if it was done with a two-part or single-part paint, use a single-part. Two-part paints are not compatible with single-part paints. The first step is to wipe down the surface with a dewaxer (i.e. Interlux 202 Solvent Wash, Pettit 15095, Sikkens M600). Don't substitute a dewaxer with acetone as it flashes too quickly and does not remove all the surface contaminants. Apply the dewaxer using the two-rag method: one rag to apply and one rag to remove. You'll need plenty of clean rags and change your rag often. Wiping a 61cm (2') section at a time is suggested. Fill any dents or gouges with a fairing compound. The next step is to sand the entire surface with 120 to 180 grit sandpaper, depending on the hardness of the surface. When powersanding, a variable-speed, random-orbital sander with a circular foam pad works best. Hold the sander perfectly flush on the surface or you'll create dips and swirl marks. Avoid the temptation of tilting the sander from the flat position when sanding areas where filler was used.

If you do a lot of painting, a brush spinner (about $30) is the most effective means to clean brushes. Get a big bucket and spin the brush inside. When handsanding, always use a sanding block (rigid or foam) to ensure that you don't add any dips in the surface that may appear in the finished surface. Remember, you are sanding to rough up the surface so the primer will have something to adhere to. Wipe off the sanding residue with a solvent (use your dewaxer for this). Mask off the waterline and gunwale with 3M Long Mask or other solvent-resistant tape. Be sure not to touch the surface after cleaning or you'll spread contaminants that can affect the cure. Now, spray the floor with water to minimize flying dust particles and change into clean clothes. You're ready to paint.

This article continues with how-to information on priming, applying the finish coat by brushing and tipping or spraying, clean up plus tips to make painting easier and a complete troubleshooting chart. To obtain the complete 9-page article look for DIY boat owner 1998- #2 issue.