Friday, 13 September 2013

Repairing the tiller pilot socket

One pieces of equipment that makes sailing the boat easier is the tiller pilot. On Auriga, it is inserted into a socket glued into the reinforced wooden lid of the starboard cockpit locker, and attaches to a pin on the tiller via a plastic end cap. Shortly before the single-handed Biscay crossing it became apparent that the wood around the socket was rotten and hardly up to the job - a consequence of pressure-fitting the socket directly into the wood and the non-slip layer trapping any moisture inside it. The socket pulled out easily, and cutting away the non-slip revealed the damaged area of approx. 10cm long, 4cm wide and 1-2cm deep. The moisture had predominantly spread along the fibers.

Affected area

 Removing the damaged wood using a chisel was easy. Once I got down to solid wood, I filed and sanded the surface coarsely.

Removing rotten wood
 A thin tube was very helpful in removing dust and shavings from the central hole. It is important to make sure the mounting hole is a few mm larger that the socket - this way the wood will be protected by a layer of epoxy.

Blowing out the shavings
 To ensure better grip of the epoxy filling, I drilled smaller holes in the surrounding wood.

Adding surface area for better adhesion

Ready to fill
 First, I mixed some West System epoxy and coated the wood surface thinly. Then, I mixed the remaining epoxy with microfibers and filled the cavity. Unfortunately, it turned out that the depth of 2cm or so is a little too much to fill in one go in the Spanish heat - the epoxy started setting quickly, and the resulting overheating lead to the appearance of a few bubbles in the epoxy bulk.

Hole filled and re-drilled - socket ready to fit
After a few hours, these had to be drilled out and the surface filed until only the solid filling remained. The central hole was re-drilled until the socket dropped in easily, leaving enough gap for a final epoxy layer.

Preparing for the final step
 For the last step, I used the same epoxy mix without filler to ensure good penetration into all the gaps. This time, it took significantly longer to set, owing to the thinner layer and the cooler temperatures in the evening.

Socket glued in place

Not pretty, but functional
The resulting fitting is at least as strong as the wood itself, with the epoxy filling distributing the load and protecting the wood from moisture ingress.

I only used the tiller pilot for a couple of hours the next morning, before setting up the windvane self-steering for the next 5 days. I engaged the former again as I was entering Plymouth and went forward to drop the sails. The push rod end cap broke almost immediately, leaving the boat spinning in the swell. There was no one to hear me curse.
While the tiller pilot is convenient in a calm, it is hardly essential otherwise - and I haven't missed it sailing into Portsmouth a few weeks later.

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