Wednesday 1 May 2024

Centreboard | Pendant & Pin Holes

As mentioned in a previous post, I decided to reinstall the centreboard pivot pin and pendant while the board was out of the boat.

The first task was to drill out the holes in the keel sides for refilling them with thickened epoxy.

I marked up the hole on both sides of the keel. This is the starboard side.


I decided to increase the diameter of the epoxy plugs to 25mm.

Next I drilled out new holes. Here I am drilling the hole in the port side, using the drill guide clamped to the keel and a 25mm Forstner bit in my little cordless Bosch drill.


This is the new hole drilled out on the starboard side.


That will provide a much larger area of cured resin for drilling the new pivot pin holes.

Then I did the same thing with the centreboard pendant holder. This is the marked up board, with the hole enlarged from 20 to 35mm.


Then I set up for drilling the new hole with the drill guide and the board clamped in place, like this.


This the new hole, drilled out with a 35mm Forstner bit.


That will allow for a much bigger opening to hold the knotted end of the pendant.

The access hole for the pendant will also need to drilled, filled and redrilled for the same reason. This is it before improvement.


I then filled the starboard keel hole with thickened epoxy, using a piece of thin plywood covered with plastic tape clamped inside the trunk, and a plastic card and a piece of ply clamped to the outside.

I squeezed epoxy into the hole while gradually moving the plastic card up the outer keel side before clamping it in place. Like this.


Next I set up for filling the enlarged pendant knot hole with thickened epoxy, with a plastic squeegee clamped under the board to seal it. Like this.


And here it is filled.


When fully cured I drilled a 30mm hole with a Forstner bit and the drill guide, as here.


Now it was time to tackle the pendant access hole, so I set up the board with a new drill guide which I got specifically for this task. Although it would have been useful for a lot of things, had I known about it!

Here it is taped in place.


The guide has six bushes to guide the drill bit - 4, 5, 6, 8, 10, and 12mm. Two pins (nails) drop through opposite corners of the plate to allow it be centred exactly over the edge of the board.

I drilled the hole out to 8mm and filled it with thickened epoxy, and when cured I then drilled a 6mm hole with the assistance of the drill guide.

That worked well. Here are both the new pendant holes after drilling.


That looks a lot better than the original holes, although I did closely follow the build manual's instructions.

Now came the time to drill the new 10mm pivot pin holes in the keel.

This time I used the new drill guide simply held in place with a pair of spring clamps.

Here I have just drilled the new holes from the port side, right through the keel and out the other side. It was an easy way of ensuring that the holes lined up exactly.


And they did. I pushed a 10mm bolt into the hole and it slid easily out the other side.

Here it is, viewed from the port side.


However, somewhat bizarrely the bolt emerges on the starboard side in a different place to where I marked up the centre of the hole. This is it.


I was somewhat alarmed at first but remembered that the initial mark up the holes and their centres was done by eye, and the drill guide made sure that the holes are in line and perpendicular.

We will find out for sure when I test fit the centreboard, which will be soon.

And that's the new holes all taken care of ... hooray!

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