Friday 24 April 2015

Building the mast slide

So this is where bits get big, and unwieldy. Bloody long sticks of wood, that have to be carefully processed and joined together accurately.

I prototyped a section of mast previously. The plan is to do a modified birdsmouth construction, from Jarrah and Tassie Oak (yes, these are my choice of timbers, both hard and dense), with comparatively thin walls, an integrated sail track, and slightly oval shape. Here's a piccie of my prototype, showing what I hope to achieve with the real thing:

The first step in construction is to create the sail track from Jarrah. This is made from two 30mm x 12mm staves, scarphed into a 6.1m length (plus a bit). I started by cutting half the sailtrack into each side with the router, and then cross drilling for 6mm dowels:

This took a little while - they're really, really long. Here are the two staves prepped and ready, in the hallway of my house as there's nowhere else with a long flat surface to do this:

Alas I didn't take a photo immediately after gluing, as I was distracted. I found applying thickened epoxy with a roller was the best way to get a consistent coat quickly, and I also found (again) that I don't have enough clamps. I made do, but there are some spots that I'll have to fill with thickened epoxy using a needle.

A piece of rag tied to a rope that was laid in the channel prior to clamping served quite nicely to clear excess squeezage.

In any case, here's the glued halves, with some slugs chucked into the track to ensure it works nicely:

My thought is that the dowels (every 30cm) will ensure the track doesn't split apart under the load from the sail.

1 comment:

Graeme said...

Mighty impressive piece of work modifying the birdsmouth method to incorporate the sail track. I'll be interested to see how much the mast weighs with the use of the denser timbers.