Making Scarph Joints in Plywood Panels

When your plywood sheets aren't long enough, they must be joined end-to-end.

Butt joints aren't strong enough. Backing blocks can cause problems when you try to bend the panels. CNC-cut puzzle joints work great – if you have a CNC cutter. So the good old scarph (scarf) joint is the standard solution.

Here's how to make one.

Criticality One

Anything that people make is going to break. This is inevitable. It's a direct consequence of unavoidable, fundamental laws of the universe.

Part of the art of engineering is to control where, and after how long, things will break. We can't prevent failure entirely, but we can focus our efforts on the most critical items and we can ensure that the complete system – an engine, boat, spacecraft, whatever – is unlikely to fail at all within a certain service life.

Crossbeam bits & pieces

Progress on the Starwind 860 prototype continues. It does seem, however, that I've fallen behind in posting updates about the boat.

The aft crossbeams are nearly done; they still need the fibreglass tape on their outer edges and a final fairing coat before painting.

The front crossbeams now have their upper mid-beam structure installed and are ready to be closed in. That task will probably take place tomorrow.


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