Upper Hull | Final Coat Hiatus

I gave a lot of thought to how I should approach the fifth and final coat of gloss on the upper hull.

Assuming that I would be able to achieve a good finish, I wanted also to minimise dust interference.

This is of course impossible to eliminate in a busy shared workspace with not very much room.

I knew that I should not try to clean up shelving, stored parts, cupboard surfaces and so on. To do so would just redistribute the dust, so I just left it all well alone.

The floor was a different matter, however. It is always dirty, with mud and leaves from the garden. And the non slip mats are full of dust after months of work on the hull.

So I got rid of the mats, and vacuumed the floor thoroughly.

Then I washed it with a mop and bucket. This is them.

I did it twice, to get it as clean as possible.

I will do it again immediately before the final coat, to lay any dust that has formed. This is a trick that I picked up from a CLC video on how to varnish a kayak. Keeping the work area damp underfoot stops dust from rising.

Now, it has turned pretty cold here in the UK in recent weeks and I was thinking about temperature in the workshop when I am painting.

It gets warm very easily using a radiator to heat the room, but I was a bit concerned to note that the relative humidity drops a lot.

The technical data for the mono-urethane gloss states that it should not be applied at lower than 10°C, or less than 50% relative humidity.

This is what my thermometer / hygrometer is showing now.

I have a temperature of 21°C, which is fine. But the relative humidity is only 35%. Which is not fine.

The air is very dry, which will cause the paint to 'flash off' quickly i.e. its solvents will evaporate rapidly leaving dry edges and brush marks.

We definitely do not want that to happen! I don't really know what to do, so I have emailed the guy at BoatPaint UK who has been extremely helpful so far.

I may have to wait until the weather improves. In the meantime I have compiled a list of everything that needs to be complete before the boat can be moved outside again, and noted which tasks can be done in advance of painting.

This is the list.

There are just 21 activities left to complete, which is amazing! Those highlighted in yellow can be performed now, so I've got things to keep me busy.

I never really paid much attention to humidity before when painting. I'm so pleased I have at last realised how important it is …

Various Parts | More Wet Sanding

Before I packed the sanding gear away I thought I would prepare some of the remaining components for their final coat of gloss.

These are the drop boards and the companionway slide.

Here I am wet sanding the drop boards with a P400 grit.

And here I am doing the same to the companionway slide.

The tabernacle and the rudder still require several more coats, so they can wait a bit longer.

We're getting there!

Upper Hull | Taping For Gloss

When the upper hull had been fully wet sanded it was time to get ready for the final coat of gloss. That meant retaping all the rails.

So I used 3M 218 Fine Line to cover the edges and 3M gold Professional to cover any bare Sapele.

Here are the starboard rub and toe rails, ready for gloss.

And this is the transom.

Part way through preparation for the fifth coat I decided to divide the task into smaller, separate areas.

This was to allow me to take my time and not rush to get large areas covered all at once.

I would be able to concentrate more on the quality of finish rather than worry about the paint curing too quickly.

So I taped off the forward deck well, like this.

I divided the cockpit into the footwell and the decks, like this.

And lastly I taped off the cabin roof and companionway hood. Like this.

I think this will make the final coat easier to apply.