Getting the Perfect Painted Finish

Most of the top coat is now on Paikea’s port hull, and it only looks this good because of the fairing underneath it. Getting from bare fibreglass to a surface ready for paint takes a lot of preparation, and on Paikea that work is Anna’s.

The video walks through how we prepare a surface: the fairing mix Anna uses, the tools she prefers, how she sands, and how she checks her work before Shayne rolls on the primer. This post follows the same order.

Our Fairing Mix

We mix our own fairing compound from four ingredients: polyester resin, wax, glass bubbles and fumed silica. Paikea is a polyester boat, so polyester resin is the right match for the surface underneath. The wax stops the cured surface staying sticky, which matters when it is about to be sanded.

The glass bubbles are tiny microspheres. They are not structural; their job is to make the cured filler easy to sand. The fumed silica is a thixotropic powder that helps the mix hold its shape on the surface instead of running everywhere. Both powders are extremely fine and they get everywhere no matter how careful you are, so wear a respirator whenever you are handling them. We aim for a firm mix, about the consistency of peanut butter. That is thick enough to stay where it is put and to give good control as it is spread.

This is the mix we use for the interior bulkheads and ceilings on Paikea: 400 g of polyester resin, 8 g of wax styrene, 1 to 2 cups of fumed silica and 3 to 4 cups of glass bubbles. The cups are small paper cups, so the powders are measured by the scoop rather than weighed.

We mix everything except the catalyst in the main batch. Then we scoop out the amount we need into a separate ice-cream container, add the catalyst to that portion only, following the resin manufacturer’s instructions, and mix it thoroughly before applying. That keeps the rest of the batch from going off before it is used.

The proportions change with the application, so treat these numbers as a starting point for interior surfaces like these rather than a fixed recipe. Adjust the balance of silica and bubbles until the mix handles the way the job needs.

Applying It and Keeping Your Tools Clean

The bulk of the filler goes on first, followed by a rough sand. Then we take a close look at how fair the surface is: where we have missed, what is flat, and what still needs work. Only then does more filler go on, and only in the places that need it.

Anna applies it with two metal spatulas, which are easy to clean and give a lot of control. Shayne prefers plastic spreaders and has printed his own coving tools for getting into corners, but Anna finds those harder to clean, so metal suits her better.

The big advantage of metal is the heat gun. Filler builds up on the blade, and a quick pass with the heat gun (with a respirator on) softens it so it scrapes straight off. That cannot be done with plastic. It matters because a dried lump of filler on a spatula will gouge the flat surface being built, so keep tools clean as you go.

Sanding: Orbital, Longboard and Foam Block

For the rough shaping, Anna uses an orbital sander with 80 grit. It is light enough to hold overhead without tiring, and gloves are worth wearing because the filler is handled for hours at a time.

On flatter surfaces a longboard does the work, helping bring the whole area fair rather than just smoothing the high spots. The longboard used on Paikea is made from foam, so it is light as well; avoid anything too heavy. For trickier areas, or anywhere that is not quite fair, a small block takes over, which is just a piece of foam found lying around, with 80 grit on it.

There is one limit to watch for. If you sand down to the fibreglass underneath, you cannot take that area down any further. Stop sanding there and fill it instead.

Checking Your Work With a Torch

The best check is a torch. On a big white surface it is hard to tell what has been sanded and what has been missed, and ordinary light hides a lot. Shine a torch along the surface and every bump, hollow and missed patch shows up straight away.

We use it after each round of sanding to decide where the next lot of filler needs to go. It turns “that looks about right” into something that can actually be seen.

Primer, Then Top Coat

Once the fairing is as fair as it can be, Shayne can put an epoxy primer over the top. The primer seals everything, keeps it all tied together and gives the polyurethane top coat a good surface to bond to.

We are painting Paikea with a local Spanish industrial paint (TKRom) rather than a marine-grade one. It is harder and more durable than marine paint, but it is set up to be sprayed with a big gun, so Shayne has to adjust it with reducers and retarders to get it to lay flat. We roll it on rather than spray, to avoid the overspray and the masking that goes with spraying.

Because the shaping and flattening is already done by the time the primer goes on, prep before top coat is simple: go over the primer with 150 grit, sometimes 120, to take the shine off and leave a flat, key surface for the top coat.

One tip that makes a real difference: put a foam pad on the orbital sander. The orbital with its firm, flat disc is quite aggressive, especially on a surface that is not perfectly fair, and it can sand through the primer in places. The foam pad is gentler and takes off just the top layer. Here is the link to the foam pad we bought from Amazon Spain.

Blending Different Surfaces Into One

Paikea is a production boat, and many of her surfaces were never meant to see the light of day. The idea was to put the boat together quickly and cover the imperfections with a liner, so in some spots the structure is a real mess.

In the interior, we have to blend three very different kinds of surface. The original bulkheads, built when the boat was first made, are not smooth. The infused flat panels Shayne builds are very smooth and need only a little taping and fairing. Then there are curved panels from an old race boat, like the carbon and Nomex Alinghi 5 transom extension that now forms the roof of Oliver’s cabin. The new seats are infused glass and foam panels in place of the old timber ones.

Our aim is to make all of that look like one cohesive piece. It will not be a mirror finish, and it cannot be, because the underlying structure has undulating shapes. Even surfaces that are supposed to be flat are not. What we can do is blend the different heights so the surface looks continuous and smooth, and make the old bulkheads sit comfortably beside the new work. That takes a bit of practice.

Why We Chose Paint Over Liner, and Why the Fairing Stays Thin

The decision to paint rather than line the interior was made early on. Shayne’s first thought was a liner like the one he had worked with on the Gunboat 68s, which sounded great, but liners can be marked and damaged and need a fair bit of work to install and fit properly. With three kids aboard, we wanted something very simple, and we also wanted to be able to see the boat we live in. We knew it would be a lot of work, but after a bit of testing on one of the bulkheads that was exposed when the new chainplates were installed, we knew painting everything was the right decision.

Once we had decided to go with paint, the critical condition was that if everything was going to be faired, we had to keep the filler on every surface to a minimum. Too much filler would add weight, and it would waste material, because it goes on and then most of it is sanded off. So we had to learn how much to apply, and how to apply it quickly before it goes off in the bucket. There is a real technique to putting it on quickly without applying more than will need to be sanded away and wasted.

The result shows in the video. The fairing on Paikea is not pure white. The speckled look of the structure underneath comes through, which shows how thin the layer is. That is exactly the aim: the absolute minimum needed to get the surface fair.

Planning Where the Paint Stops

Because Paikea is being painted in sections, we have to think ahead about how far each top coat runs, so the next section can be blended in without the join showing. A doorway is ideal, because it gives a clean, abrupt edge. Shayne can paint up to the doorway of Oliver’s room, for example, and pick the next section up from there.

That is why we finish each stretch of prep before painting. Once the next piece is ready, we can blend the top coat where it makes sense.

In the Library

This prep work sits inside the wider interior refit. To see the structure the fairing is covering, start with Paikea’s Bulkheads, and for the materials and techniques behind it, browse the Working with Composites hub. In the next video, we move on to installing Paikea’s synthetic sidestays.