Sunday 19 December 2021

Hull Bottom Panels | It's All Coming Off!

Examination of the hull the following day revealed, as suspected, that the first coat of gloss on the bottom panels had not been a great success.

Brush marks in the primer showed clearly through the gloss, and although it wasn't really awful I knew it could be so much better.

I could also see where the wet edge was, well, no longer wet and had dried in numerous places. Not good.

The level of finish would have been OK in a house interior, with an eggshell or satin finish, but it wasn't nice enough for the high gloss surface of a boat.

So I made the decision to sand it all off and start again!

This is the port bottom panel, part sanded to P120.

And here is the bottom of the hull fully sanded port and starboard.

I expected the first round of painting the hull to be a learning experience, and it certainly was.

Key lessons learned were:

1. Primer has two distinct but equally vital roles - to provide a) a solid colour base and b) a perfectly flat surface for the gloss.

That means several coats sanded to a really fine finish, with no bare patches.

2. Despite the manufacturer's recommendations, there was no way that a really nice finish could be achieved without thinning or conditioning the gloss.

So some experimentation was required before we painted the hull. Again.

I decided to try proper paint conditioner, as shown in every 'how to paint marine gloss' video that I had seen.

The stuff that seems to be available in the UK is called Owatrol.

It's only available in trade outlets and is ferociously expensive, so a I bought a small can for the trial.

Here it is.

The instructions tell us that it should be added to paint between a 5% and 20% ratio.

So I mixed a quantity at 5% and applied it to the centreboard by way of a test. This is what it looked like.

Not too bad at all!

I also glossed the drop boards, like this.

Encouraged by the improved results I applied two test patches to the hull, as here.

I tipped out one patch with a foam brush, and the other with a bristle brush, to see which gave the best results.

So now we wait and see how it dries, and if this is the way ahead. 

Hull Bottom Panels | More Primer & First Gloss

I haven't posted for a while because there simply hasn't been anything of great visual interest to report.

I have spent the last few weeks learning how to paint a boat, or more specifically how to use marine paints. It doesn't behave anything like household paint, and advice on what to do with it varies widely.

In the previous post I had sanded the bottom panels to a really smooth P120 finish and was ready to repaint them with primer.

More primer arrived a few days later and I prepared to thin it, as recommended on the 'how to apply primer' video tutorials which I had researched.

So I read the instructions on the tin before proceeding, and was dismayed to read "Do Not Thin".

Hmmm. I called the paint manufacturer and asked them about thinning the primer. They said that would be OK for spraying, but 'not recommended' for brush and roller application. In other words, don't do it.

The new paint certainly flowed better than what I had been using, so I showed good faith and applied three coats over several days by careful rolling and tipping.

This is what it looked like.

It didn't look too bad so I went ahead with the first coat of gloss.

Again, this is what it looked like.

I wasn't convinced that it was good enough, so left it until the following day.