The rumor going around the waterfront is that painting the topsides of a boat is expensive. But that’s only if you want to keep a boatyard fully employed for a few weeks while your boat is being worked on. If you do the work yourself, the cost will be far lower. In fact, about 90 to 95% of a good paint job is in the preparation. The last four hours of work are when the topsides are actually painted. This is the time that gives you the shine that you will look at for many years to come.
Consequently, you can save a huge amount of money if you do the preparation work yourself. Fully 70% of the preparation is sanding. You’ll need to fill any scratches and then sand, fill scratches again and then sand again. After a lot of filling and sanding, you’ll be ready to apply the undercoat of paint, and then you’ll sand some more. Next you’ll apply the primer coat and do even more sanding. The easy part, comparatively speaking, will be the painting. That will take only a couple of hours, and even fewer if you have a spray gun. It is the sanding that will take you days to obtain a great finish.
The sanding must be perfect – at least as perfect as you can get it. You must not be able to see or feel even the slightest scratch or bump. I thought I had a great finish until the professional from the local boatyard looked at it. His comment was “It’ll look okay when you’re on the other side of the dock.” So I sanded again and again until he was satisfied. Then he, the professional, sprayed on the finish coat for a few hundred dollars, with me supplying the paint.
Buying the Paint
The first step is to decide what color you are going to paint your boat. It is important to make this choice early because you may need to order the paint. Of course, you’ll also need to figure out which brand of paint to use. The industry leader is Awlgrip, but it needs to be professionally applied. Plus, to ensure compatibility, you should use all the other Awlgrip products, such as Awlfair, Awlprime, and so forth.
A more appropriate option if you are not a professional painter is to use Perfection, one of Interlux’s topside paints. Perfection is formulated for amateur application by brush (using the roll and tip method) or by spray. If you decide to use Perfection, you should use the Interlux range of products to ensure complete compatibility. Because I used Perfection, I’ll be showing Interlux products throughout this article, but you can use paint and compatible products from other manufacturers if you wish.
Filling and Sanding
When you are ready to begin the job of sanding, check on the state of the current paint layer. If the gel coat is crazed or heavily oxidized, you will need to sand it with 100-grit sandpaper using a random orbit sander. If the gel coat is only lightly oxidized or has been painted before, you might be able to use 220- or 320-grit paper from the start.
Be sure to also check your topsides for dings and scratches. These should be filled before sanding. Sanding will allow any remaining marks to show through, which you can then fill again. Take your time with this process to get a nice smooth finish. The boat’s entire finish is based up on you doing the sanding properly. Use a random orbit sander for the first cut and a longboard style sander for finish work. Don’t use a finish sander or rotary sander. Finish sanders don’t cut deeply enough and a rotary sander leaves swirl marks in the gel coat.
When working with sand paper, several studies have shown that most people use too fine a sandpaper to give a good “tooth” to the surface. If the gel coat is heavily oxidized you should use 220 grit or even 100 grit to get the oxidation layer off. The final coat before spraying should be 320 grit, but many painters suggest that 400 grit should be used. I’ve found that 320 is usually fine when used with a longboard.
Applying a Prime Coat
If the hull has not been previously painted and you are using Perfection as your topside coat, you will need to prime the boat with Interlux’s two-part Epoxy PrimeKote. Do this by thinning the paint with a compatible solvent and rolling it onto the topsides. Tip the rolled paint with a dry paint brush to remove runs and streaks. Always keep a wet edge to the paint and start and finish under the transom where errors won’t be seen.
To Get a Great Finish
Roll and tipping paint
To get a good finish, roll the paint onto the hull with a paint-loaded roller, and then use a dry 3” or 4” paint brush to smooth the paint layer. Just use the tip of the brush with no paint on it and smooth the paint. Be sure to work from the masking tape to the masking tape so that you do not apply or lift the brush in the middle of the job, creating marks on the surface. I find that working from sheer to boot-top is the easiest.
Now for more sanding. After the prime coat has been applied, sand the entire hull once again using 320-grit. Make sure that any dings or scratches have been eliminated. If you have to apply more filler, do so, and then paint over them again. Be sure to sand the painted area carefully.
If you want a really great finish, mask off the boat and spray the hull with a primer that has been mixed with some of the topside color. This gives you a good base coat that helps reduce the amount of topside paint you’ll need. Once the boat has been sprayed, sand again using 320- or 400-grit paper. At this stage you should not be able to see any scratches at all in the paint. Some painters say that you need to sand again at this point using 400-grit paper, but research done by 3M and others indicates that 320-grit is fine.
Now comes an equally important step – topside painting. Mask off the hull and spray it if you know how to use a spray gun. If not, have a professional do the spraying. The actual spray job should take about four to six hours depending on the size of your boat. It should therefore cost about $400 to $1000 dollars depending on the going labor rate of the boatyard and the time needed for the painter to clean up.