Doug,
I was aware of Colchide’s set up. But learnt something new with Trevor’s insight about the signal not penetrating a wooden hull.
Like Trevor’s installation, I already had a through hull hole, as well as both internal and external shaped pad pieces which follow the contour of the hull so that the transducer’s face sits horizontally.
Only slight problem is that it is very close to the boat’s centreline – which to be fair is where it ought to be – and risks fouling the trailer if I don’t watch it carefully.
Good luck!
Mike