Wednesday 27 March 2019

Support Beams

I meant to add a note to the previous post about the need for support when leaning into the hull to work on the boat. Copying other builders I fixed blocks to the tops of the cradle arms and clamped support beams to them, like this.

Without these it would be difficult if not impossible to work safely and comfortably when leaning into the boat. As it is I could only just reach the centreline when wiring in the bulkheads and floors. You need long arms for this build!

On the same subject it is essential to have the keel supported properly at the stern, to stop the boat tipping backwards. Here is the support block which I made.

Next phase is tack welding everything together with epoxy. Should be fun!

Fitting Bulkheads & Floors

With the transom in place and the hull reasonably rigid, I fitted the bulkheads and floors working forwards from the stern.

Bulkhead number 8 went in easily. Here it is wired in place.

I have switched to using galvanized steel garden wire for the stitches. Copper wire is no good where a strong stitch is required and I realised that the plastic covered wire I had used in the bow panels would be problematic if I had to use a heat gun to remove it from the epoxy welds and fillets. I resolved to replace it with steel wire as I progressed along the hull.

Next came bulkhead number 7. Here is it is wired in place.

This was slightly troublesome. It is not clear to me if this bulkhead is supposed to align with the build cradle or not, because here it did both!

In a previous post I stated that the cradle is not totally rigid or dimensionally accurate, so I stitched in the bulkhead where it is designed to fit and ignored its interaction with the cradle. For some stitches this meant drilling through the cradle. In the end it fitted nicely.

Then I fitted floors 6, 5 and 3. I also rewired floor 4 with steel wire rather than the copper I had originally used. It works much better. Here are the floors in place.

In order to keep the side and bottom panels aligned inside-edge to inside-edge in the run to bulkhead number 2, I fitted alignment blocks on each side, as here.

As it turned out they were not really necessary, but it reassured me to know that the panels were true.

Next came bulkhead number 2. I expected to have some trouble getting it to fit snugly against the bottom panels where they start to curve strongly, but in practice it went in quite easily. Here it is stitched in place.

There is a tiny sliver of daylight between the bulkhead and the bottom panel in the centre on each side, but nothing that a tack weld will not fill.

So far so good! Now for the bit that I was pretty sure was going to be tricky … bulkhead number 1 and closing the gap between the side and bottom panels at the bow.

First I test fitted the bulkhead and secured it temporarily in place with clamps, as here.

Then I tackled the gap between the panels, which looked like this. This is the port side.

Note that I have replaced the plastic coated wire with steel wire.

I thought the gap looked horrendous but the manual talks about how to close it and it is a regular feature in other builders' blogs, so I remained resolute and followed instructions.

I received some excellent advice from Tassie Pete and River Ron on the CLC PocketShip forum, so thanks to you both for your help. It's very reassuring when you know that someone else has encountered and solved the same problem.

First I made some adjustment tools to pull the edges of the panels into alignment, just as the build manual says to do. They worked well. Here they are deployed on the port bow.

Then as advised by my fellow builders I fixed a pair of blocks to the panels and used a clamp to close the gap, like this.

It was all turning out quite well.

I then repeated the process on the starboard side, which turned out like this.

The gap was now much reduced to the extent that epoxy tack welds will fill it, and I'm happy with that. Hooray!

Now it was time for bulkhead number 1. Here it is stitched in place.

You can just see a small block of wood that I fitted temporarily to pull the side and bottom panels together where they join at the bow. Here it is close up.

I now see that this is exactly where the bow eye will be fitted, and I think I will replace this piece of soft scrap with a piece of good hardwood to give the bow eye a strong seating. I will most likely do that when I do the fillets.

There is also a bit of daylight showing between the bulkhead and the bottom panels. I'm not sure it matters, but I will ask for advice on the PocketShip Forum before attempting to close it.

Also, having shed blood many times during this stitching exercise, I trimmed and taped all the steel wire stitches. They are lethal, and I don't want visitors bleeding all over my plywood ...

Lastly, as the build manual tells you, "Step back and admire the assembled hull".

This is the view from the bow.

And this is the view from the stern.

In the space of just a few days, PocketShip really has taken shape.

It's immensely satisfying. Time for a glass of something cold to celebrate!

Tuesday 26 March 2019

Fitting The Transom

The time had come to fit the transom - a day I had been looking forward to for a long time as the milestone event when the various panels which I had spent many weeks making would come together in the shape of the lower hull.

The hardest part of this task was holding the heavy piece of 18mm ply in place (single handed) when marking in the bevel. In the end I found it easier to measure the bevel with the transom held in place, and mark it in on the bench. The bevel is 4mm on the sides and 9mm on the bottom panels.

I made the bevel with my jack plane, like this.

It did not take long. Then I fitted it in place using temporary dry wall screws, as here.

I am using small pads of ply to protect the hull from the screw heads. It fitted very well first time. Here is the view from inside the hull.

Now it really does look like a boat!

Saturday 16 March 2019

Fitting Side Panels

With the bottom panels in place I installed the side panels. This was relatively straightforward, but again the copper wire only works where there is little tension in the joins. Steel wire was necessary at the bow.

Here is the starboard side clamped and wired in place.

And here is a view of the bow section, wired in place.

Next the port panel was wired in.

The sides were wired together at the bow, like this.

It's starting to look like a boat, at long last!

Fitting Bottom Panels | Third Cock Up

With the keel assembly now resident in the build cradle it was time to install the bottom panels. I wired in the port panel first, without much difficulty. I initially thought the copper wire supplied in the kit would not be strong enough to pull the panels into place, but it is adequate where there is little or no tension to overcome.

It was only when I wired in the starboard panel that I realised there was a significant problem with the keelson. I had clearly put too much rocker into the top of the nose block, causing the keelson to have excessive upward curve from the forward face of the centre board case to the end of the keelson.

The bottom panels and the unhappy keelson looked like this.

I would obviously need to modify the nose block so that the bottom panels would lie snugly alongside the forward end of the keelson. I let the panels fall where they wanted to against the nose block and scribed in the correct curve.

I removed all the wires and set the panels aside. As I moved the keel on its wheeled cradle I managed to snap the tip off the keelson when it knocked against the wall. What a great way to end the day.

It was now clear that I would need to make a new section of the keelson rather than reuse the weakened old one. The third cock up had unfortunately turned out to be non-trivial!

The following day I took the plunge and cut the keelson away from the nose block with a panel saw, back to the point where the excessive curve began. Cutting into something that took weeks to make is not a good feeling …

This was the result.

You can see that there is far too much rocker in the top of the block, which surprised me because I took great pains to make what I thought was a fair curve from the top of the keel. Oh well.

Next I used a tenon saw to make short vertical cuts down to where the true curve was marked, like this.

Then I pared away the waste with a chisel.

And then I faired it to a smooth, even surface. Here is the reprofiled nose block, ready for its new section of keelson.

I used the piece I had removed from the keelson as a pattern to make a new part, and fitted it. Here it is in place.

I left it to cure for three days to be sure it was strong enough to survive any strain in the next round of panel fitting.

Then I fitted both bottom panels by wiring them along the length of the keelson. They fitted snugly alongside the new section.

I left wiring the two panels together at the bow until last. There is a lot of bend in there and it looked like it would be difficult. It was. They really fought back.

The copper wire was obviously not up to the job for this so I used plastic covered steel wire. It worked really well.

The build manual recommends using hot water to make the plywood more flexible, so I used a couple of tea towels soaked in hot water to warm the bow area. I am not sure it did much good - they cooled very quickly.

A ratchet clamp however helped enormously to pull the panels together.

With patience, the strong wire and the clamp the panels were successfully joined together.

I chamfered the inside edge of each panel at the bow to get them to sit snugly together, and drilled a lot more holes.

Lastly I wired floor 4 in place.

It seemed to fit quite nicely in the hull, where it should, but it did not fully align with the build cradle as the manual said it would. That is because the cradle is quite a crude structure, made of MDF and studding timber. It could not possibly be dimensionally accurate to the extent of the CNC cut ply components, so I just wired the floor into the correct place and forgot about the cradle.

All is well, and the boat has a bottom!

Monday 4 March 2019

Finishing The Keel

With the lead all poured it was now time to complete the keel by fitting a cap to the rear keel and then installing the keelson.

But first I had to clean up the lead in the front keel. I poured a bit too much lead into it and the excess had to be removed.

I thought an angle grinder would make short work of this and I bought an inexpensive one from the DIY store. Following the instructions I set it up and tested it, coming to the final page of the manual which states that grinders are not suitable for soft metals such as lead and aluminium. Oh dear.

Undeterred I tried it anyway and sure enough it was useless! It merely pushed the lead around, like trying to spread cold hard butter. So I gave up on that.

Out came the mallet and chisel, which was only slightly more successful and promised to take a very long while to do a good job.

Finally I did what I should have done in the first place, which was to deploy the Shinto saw rasp. It is intended for this sort of thing and made an excellent job of cleaning up the front keel. Like this.

Next I coated the inside of the rear keel buoyancy compartment with clear epoxy, which I had neglected to do when assembling the keel. I used a long handled roller, like this.

Then I used the keel blocking pattern to cut a cap to fit into the top of the rear keel.

I glued it in place and when cured trimmed it flush with the top of the keel sides with a sharp chisel.

With the cap in place I next test fitted the keelson, as here.

I found that the top surface of the keel was not absolutely level along its entire length, only by a millimetre or so but enough for the bubble in the level to not sit squarely where it should.

So I made some blocks out of MDF, each fixed with a  pair of drywall screws to hold the keelson down against the curve of the keel and by adjusting the pressure of the two screws I was able to get it exactly flat and level along its whole length.

And after some further experimentation I glued three small hardwood shims where needed to level the keelson on the starboard side of the centre board case, and fastened them in place with small bronze ring nails.

Then I applied plenty of thickened epoxy to the top of the keel and fastened the keelson in place, testing that it was still flat and level along its whole length.

For some reason I forgot to take any photos of the keelson at this stage, all fastened down and curing, but here it is after the fastenings were removed and the keelson cleaned up.

The keel was now ready to be dropped into the build cradle, which I had assembled while finishing the keel.

Here is the completed build cradle.

I didn't take many photos because it didn't seem that interesting, to be honest. The two halves of each cradle end are joined by a length of 3 1/2" by 1 1/2" timber along the bottom edge. I glued and screwed them for strength. I fitted backing pads on the other side at each corner and mounted the cradle on braked casters, so I can move the boat around easily during the build.

Each caster is rated for 120 kilogrammes so the cradle will easily support the hull and my weight when I need to get inside it to work.

And here is the keel dropped into the build cradle.

You can see the port bottom panel in the background, leaning against the workbench and waiting to be fitted.

The keel's centre of balance is at the rear of the centre board case, right where it rests on the stern build cradle. It tends therefore to tilt when being moved or handled, so I clamped a piece of scrap against the aft end to keep it level. Like this.

The keel will need to be securely blocked up during the build to prevent this being a problem.

Finally I rounded over the edges of the centre board case which will be visible inside the cabin.

I used a 1/2" round over bearing guided cutter in the router. It worked well.

That completes the keel and it is now ready for the bottom panels to be installed.

The hull will, at last, start to take shape.

Saturday 2 March 2019

Pouring Lead

At last the cold wet weather cleared, and the morning of the 19th February (my birthday!) dawned bright and dry. So I immediately set about getting the lead pour underway outside on the driveway.

I tackled the centre board first, for practice, with it requiring a relatively small amount of lead and being easy to set up.

Here is the centre board clamped to the saw horses and levelled flat.

I wanted to know exactly how much lead was going into the centre board and the keel, so I could be sure the boat is correctly ballasted.

I had previously cut all the rolled lead into pieces for melting, and weighed it all out using the old fashioned balance kitchen scales and brass weights. In the process of doing this I discovered that this method was only roughly accurate, so for the pour I used an accurate set of scales and switched to measuring in kilogrammes.

The drawings state that the centre board requires 9 kilogrammes of lead. I weighed this amount out in three lots of 3 kilogrammes, because as mentioned in a previous post I was doubtful that it would all fit into the aperture and I wanted to pour in smaller amounts until it was full.

Then I donned face shield, respirator, boots, overalls and heavy gloves. I think the neighbours were wondering what was going on.

Breaking Bad in Eynsham? Surely not?!

Then I fired up the burner and somewhat nervously started to melt the first batch of lead in one of my old stainless saucepans.

In no time at all it melted, so I skimmed off the dross with a stainless spoon and poured the first lot into the board.

It all went smoothly and I filled the aperture half full, immediately realising that as I thought there was no way it would take 9 kilogrammes.

The second pour filled it to just slightly overflowing, with a total of 6 kilogrammes used.

Here is the freshly poured and cooled lead.

So far, so good!

I then got set up to pour the front and rear keel ballast. I improved the shelter around the burner, partly to protect the flame from the light breeze but also to deter curious passers by from getting too close.

Then I set up the keel, like this.

Heavy building blocks hold the keel securely upright, and a pair of heavy duty F clamps hold them in place against the sides of the front keel so they won't bulge when I pour the molten lead into it.

This went smoothly and the front keel took 7 kilogrammes to slightly overfill it, so the drawings are correct here.

The rear keel pour then went ahead, with the clamps moved aft.

The compartment did not seem big enough to take the 42 kilogrammes specified in the drawings, but it easily swallowed it all up. Here it is full, with a gap left at the top to take the keel cap.

I poured in batches of 6 kilogrammes, since I thought that was the most weight I could safely handle in one go.

So that was the lead pour successfully completed. It took four and a half hours in total. I left the keel outside to cool until the evening before moving it back into the workshop. It is now too heavy to lift without help!