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.

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