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.

Thursday, 25 November 2021

Primer | First Coat & Rework

With the waterline now correctly in place it was time to apply paint. This was truly a momentous step in progress!

The primer undercoat for the bottom is white, and that would be the first paint to be applied.

A previously opened can was reopened and was found to have gone off, so a litre of expensive paint went to waste.

A second can was opened and the first coat was applied to the hull bottom, centreboard, drop boards and rudder.

This is what the hull looked like.

It was pretty patchy, unsurprisingly.

A second and a third coat were applied which covered really well but there were still very  visible brush marks after the third coat.

There should not have been any because I was using the recommended technique of 'rolling and tipping' which entails applying paint with a roller and then tipping it out with a quality paintbrush to remove the air bubbles and brush strokes.

There were no air bubbles but the finish was not good enough for a top coat.

So I looked at a few 'how to paint primer' videos on the internet and realised that that I had done two things wrong.

I had not thinned the primer to allow it to flow freely, and I been applying paint from the wet edge outwards instead of in the other direction.

Thus the paint was too thick and the brush dragged on the wet edge.

So.. back to square one. I would clearly need to repaint the bottom of the hull.

I wasn't too disheartened because I treated this as a learning exercise on a part of the boat which no one would see, so it was OK to mess up.

Accordingly I sanded the bottom panels to beautifully smooth P120 finish. They looked like this.

It was as expected very patchy and would need to be repainted.

I had run out of white primer, having used two litres to get thus far.

This was a Friday evening of course and it would be the middle of next week before more paint would arrive, so things are at a temporary impasse.

Time for a G&T.

Waterline | Marking Up - Twice!

The build manual states that the waterline on the prototype was set at 16 1/2" above the bottom of the keel, so that's where I marked it in. Like this, using a rule and a tape measure.

Then I used a laser level to mark the waterline across the transom, as here.

This is the laser level itself.

I initially bought the cheapest I could find, reasoning that I didn't need a quality instrument for such a small job.

Big mistake. The cheap level was rubbish and was promptly returned to the store, and this one was purchased instead. It worked perfectly and I am very happy with it.

I pencilled in the waterline across the transom and used the laser level to continue the line around both sides of the hull. This is the laser line on the port side.

I pencilled in marks at short intervals and joined them with a straight edge to get a nice, fair, flowing waterline.

Here the line is crossing over the chine on the forward end of the hull.

So far, so good!

Happy with progress I taped in the waterline using some 3M Fine Line tape. It's really good tape, and conforms easily to curves.

Here is the view from the starboard bow.

But I soon realised that something was not quite right.

The waterline was symmetrical until it passed over the chine and back to the transom on the bottom of the hull. At this point it joined the transom at slightly different places port and starboard.

After some head scratching I worked out that this could only be because the hull itself is not perfectly symmetrical. The difference was very small - a few millimetres - but of course over the length of the boat this is amplified to a visible extent.

Given the method of construction this is clearly going to be an unavoidable issue. I needed to find a way to do this correctly.

I needed a datum point on the hull where I could be sure that the waterline was in exactly the right place.

As is often the case with PocketShip there is no such measurement in the drawings, so I examined photos of the prototype and noticed that the waterline crosses the chine at the front of the boat exactly below the forward edge of the forward porthole.

I used the laser level to check this on my boat and immediately saw a problem.

This is what the starboard side looked like.

It's way off where it should be, and wasn't even the same on the port side!

So off came the tape and the incorrect pencil line was sanded off.

Then I marked where the line should cross the chine on both sides and used the laser level to mark it from that datum point.

That went well and I now knew that the line on each side was exactly where it should be. The tiny visual discrepancy at the transom was removed by adjusting the waterline by a fraction on each side.

That looked great and I was happy, so a second waterline was taped up. Here is a view from the starboard bow.

That was very satisfying in a perverse and masochistic way! 

Levelling The Hull - Again!

I wanted to be certain that the boat was exactly level when I marked in the waterline, so I double checked using a long level taped to the keel, as here.

I had previously only used a short level to do this, and sure enough the much longer level showed that the hull was not level fore and aft.

A similar exercise on the transom showed that it too was not exactly level, like this.

So the bottle jack was employed to level things up at the stern, as here.

And at the bow.

All was now ready for the waterline to be added.

Bowsprit & Mast | Pivot Holes

I would soon be varnishing the spars so pivot holes in the mast and bowsprit needed to be drilled.

First I set the bowsprit in place to mark up the hole, as here.

Then I set the bowsprit up on the pillar drill and clamped it in place, like this.

A spirit level ensured that the bowsprit was level and that the hole would be exactly perpendicular. Like this.

Here is the drilled hole.

I found that the drill did not have sufficient depth of travel to drill all the way through, so it had to be drilled from both sides. All went well.

The mast was next.

Here the mast is set up in the same way as the bowsprit, checked with a spirit level.

Lastly here is the drilled mast hole, again drilled accurately from both sides.

That was fun!

Keel | Pivot Hole

While drilling the centreboard I also drilled the pivot hole in the keel.

When I assembled the keel way back at the beginning of the build I thought it would be a miracle if the the pre-drilled port and starboard holes lined up exactly.

I was right. First I drilled the starboard hole, as here.

That looks OK, but when I drilled through and out the other side this is what it looked like from port.

Hmmm. That needs to be filled and re-drilled.

First I enlarged the misaligned hole with a rasp, like this.

Then I filled the hole with thickened epoxy and clamped a couple of plastic cards in place to retain the mixture. Like this.

This is what it looked like when cured.

Lastly I sanded off the excess epoxy and drilled a new hole, as here.

 All's well that ends well!

Centreboard | Pivot & Pendant Holes

It was time to get the centreboard ready for installation.

So the pivot and pendant holes had to be drilled.

I used the drill guide to make the holes through the board, to ensure that they were perpendicular. Like this.

I then carefully drilled a 9mm hole in the edge of the board, like this.

I filled this hole with thickened epoxy. A bolt wrapped in tape and passed through the board kept the epoxy in place, as here.

Lastly I drilled a 6mm hole through the epoxy plug for the pendant itself. It looked like this.

So now we have strengthened waterproof holes in the centreboard.

And it's ready for paint!

Hull Exterior | Clear Coating & Sanding

 A lot of sanding was required to get the hull to a suitable condition for paint.

The manual states that we could easily spend a day sanding the hull. I 'easily' spent several days on the requisite three clear coats of resin.

This is the part sanded hull after its second clear coat.

I am using the Rotex 90 sander with a medium-soft head in finish-sand mode. It works really well on curved surfaces.

This the hull after its third and final clear coat.

This is what it looked like after final sanding to P80 grit.

The bits of blue tape mark where a small ding needs to be patched or faired. There were very few.

And while I was at it I sanded the rub rails and rounded them over with a rasp and some sandpaper. As here.

They are looking nice!

Hull Exterior | Bubbles & Patches

When I sanded the fibre glassed hull I discovered that there were a number of tiny air bubbles on the side panels only.

They looked like this, with a rule for comparison.

I wasn't sure if this was a problem or not, so asked the vendor for advice.

They said that the bubbles were tiny and I should sand them out and coat them with epoxy.

I decided to grind them out and use fairing compound to get a flat surface before applying more epoxy. I used a small burr in the drill, like this.

This is what the ground out bubbles looked like when filled.

 Here they are after sanding and a second coat of epoxy.

I also managed to sand through the fibreglass on the hull in one or two places, so I applied patches to them, like this one on a puzzle joint.

I made the patches oversized to allow plenty of room for feathered edges and to provide strength.

We're getting there, slowly but surely!

Hull Exterior | Transom Fibreglass

I decided to make a pattern for the fibreglass panel on the transom. Here I am cutting out the panel from the pattern.

Once again the stuffed chicken doorstops had their role to play.

This is the panel on the transom, held in place with tape.

 A second clear coat was applied to the hull, as here.

And lastly the transom received its first clear coat, wetting out the fibreglass. Like this.

Looking good!