In many classes such as Mini 650s, Class40s and Imoca60 it is mandatory to paint your boat number on the deck, in Cat Zero events you also have to paint an area of 4sqm in high visibility colour. I’ve seen work done so badly on new boats that it made me cry. Painting numbers is not easy and doing it well even less. The most complicated case is when your non slip is of diamond shapes in the mold of the deck as seen on many production boats rather than a non slip paint finish. This is because any when trying to mask the masking tape will not create a good seel with the diamond shapes of the gelcoat deck. We cant sand down the diamond shapes to get to a smooth surface, so ideally we want to preserve the non slip properties of the deck but still be able to paint over it.
If you have to apply anti-slip to the whole boat, it is no small job. When talking of standard non slip paint, rather than a gelcoat diamond grip, if the old paint is just faded or worn out, you may want to apply a coat over the old one. But, if it peels you will be forced to sand everything down. This is if you want to apply the anti-slip on smooth deck get a good result.
If you need to paint the numbers on a new boat or refresh them, you must first sand down and return to gelcoat, in case of a diamond finish you need to clear off the peeling parts with a wire brush or carefully with a blade to preserve the diamond shaped gelcoat. Painting new numbers over old ones will probably be a bad job. Also because colours like red don’t have a great coverage capacity and you have to work on a white background. If the background is uneven after sanding, apply a primer or a white undercoat. Then you will have to paint the number the same way you can use to apply anti-slip on deck
Apply the anti-slip on deck: masking
Before starting, you have to tackle one of the longest and most boring jobs, masking everything you don’t want to paint. You will need some blue or green masking tape, capable of stretching to follow curves. You will also need a cutter blade for the places where it will be easier to tape and cut off the excess.
Going back to the numbers, trying to write them by hand with masking tape will result in a bad job. Go to any graphic design shop and for a small sum they will print the numbers or rather the negative frame. Have them print it on the same adhesive material you use for masking. When placing the number on the deck, everything is easy if you stick the mask on a smooth surface. If, on the other hand, you have sanded the number but you have still anti-slip at the edges of the sanded area the work is more complicated.
The mask will not adhere well to anti-slip painted surfaces and when you paint the number the paint will find its way under the mask. But here’s a secret on how to apply anti-slip and mask even the most difficult spots. For these situations you can go to a DIY store and buy some butyl. It is the mastic used to lay kitchen sinks, it does not dry, it does not stick permanently but stops the paint. Once you have placed the number (or the area to be masked) make a very thin butyl salami and press it on the edge of the mask. Once pressed well, follow the outline with a cutter and remove the excess butyl from the side to be painted.
Apply the anti-slip on the deck which had previously been sanded smooth.
If you need to apply the anti-slip on a smooth surface you will have to prepare the mix of the paint with the anti-slip grains. If you are not an expert I recommend you to paint with a roller and not spray paint. However, roller painting can lead to some dreadful results if don’t know how to. While we paint, the non-slip grains settle on the bottom of the tray and the density of the grains will end-up being uneven.
But here’s another little trick to apply the anti-slip so that it comes out regular. To obtain uniformity, prepare the anti-slip paint and pour it into a bottle with a spout of the type used by runners. A well-dried water bottle is fine, you can also make a hole in the cap of a bottle without an open-close spout.
At this point, with your roller ready, shake the bottle and then pour some paint and antiskid mix. Spread it with the roller and always shaking the bottle first, continue pouring and rolling. Each time the paint will have a constant density of antiskid and the final result will be more than acceptable. This method allows you to apply the anti-slip avoiding the annoying result of seeing antiskid at different densities over different areas.
Paint on a gelcoat diamond deck
Here we are only talking about painting numbers. If we have the diamond finish gelcoat deck we don’t need to add anti-skid. The problem with the diamond finish is that it is practically impossible to seal the mask on the deck. Even using butyl it is really difficult to remove the excess on the side to be painted. At this point I recommend that you spray paint. You won’t need to add anti-slip so if you know how to use a paint gun it’s simple.
Once you have applied the mask, take care to paint from the mask towards the inside. Paint lightly and give more coats of paint to avoid possible dripping of paint that will run in between rows of gelcoat diamonds. The finished result is perfect if you don’t apply too much paint or make mistakes.
What paint to use to apply the anti-slip or to paint numbers
For all deck paint job you must always use a two-component polyurethane paint. Don’t be tempted to use a regular can spray paint. It won’t last long, it will peel off and your beautiful bright red will turn pink within a few months.