Saturday, 16 February 2019

Centre Board | Second Cock Up

I started the centre board at the very beginning of the build, while I was constructing the keel. The first step was to glue the two halves together to form a strong 18 millimetre thick board.



Here is the centre board glued up and clamped, and with plenty of lead weights to squeeze the two halves together.



This the board, cured and with the squeeze out cleaned up.

The eagle eyed PocketShip builders out there will see that I had made a simple but important mistake - I had glued the outer faces of the two halves together!

The result was that the designed rebate around the inside of the aperture to retain the poured lead ballast was no longer a rebate. It was now a sort of ledge, like this.



Quite what made me do this I really cannot say. And it wasn't until much later when I put the centre board drawings up on the wall for reference that I realised what I had done! I would need to think of a way to fix this. I could not see how this could retain the lead securely.

Before I tackled the aperture problem I cut a rebate in the leading and trailing edges of the board, as recommended in the manual.



I used my router with a 3/8" two flute cutter. It worked just fine.



Then I filled the rebate with thickened epoxy. This will provide the board with an armoured edge to protect it from damage.



I used pieces of ply covered in sealing tape to hold the epoxy in place while it cured, so it could not run down the vertical part of the rebate.

This was done in two or three stages to fill both leading and trailing edges, with the board clamped to a saw horse.

Finally I sanded the edges flat ready for shaping later, like this.



Then I moved on to the ballast aperture problem. I decided to cut back the 'ledge' to restore a clean, straight inside face to the aperture, and then to cut a rebate in that face. The router would be able to do all this, and a look through the Trend catalogue suggested that a slot cutter would be required to do the latter.

A trip to the nearest Trend stockist confirmed this. A slot cutter consists of three parts. The arbor is the spindle which is held in the chuck of the router; the slot cutter is the rotating blade which goes on to the arbor; and finally there is the bearing which guides the cutter and determines the depth of the slot. The cutter and bearing are separated by spacers and they are all held in place on the arbor with a nut. It looks like this.



Fifty six quid. That'll learn yer.

Here is the finished aperture.



I think it looks pretty good. It will take a bit more lead to fill it but that doesn't matter.

Next I fixed a piece of scrap ply over the aperture on one side of the board, like this.



This is to stop molten lead from leaking out of the underside of the board when it is poured to fill the aperture. I used plenty of temporary drywall screws.



The centre board is now ready to receive its lead ballast!


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