Saturday, 16 March 2019

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!

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