here's the second mount I built.
I've never sailed with a helmet before - but I got a standard Gath model and drilled two holes in it. the closeup shot clearly shows the polycarbonate sheet attached to the outside of the helmet.

there is a layer of neoprene cushioning the bolts from the camera casing - and to complete the design cable ties hold the entire thing rock solid.

here are some shots taken on the first 45 minute test run.
[my wave kit][G21 gets ready][dan doesn't fall in]
[mid vulcan][wave threesome #1][waterstart]
[mid tack, port][wave threesome #2][jump]

some additional notes:

I made the vulcan.
One of those waves was mast high - don't remember which one.
The jump is my favourite shot.
Dan can actually sail.