Custom shim behind trim tabs

[buckeye]

I have Bennett trim tabs on my board and because the mounting location is on a radius there is a teak shim between the tab and the boat. Anyone have any tips on the best way to replicate the radius of the transom so I can build a new board? The present one is all but rotted away.

 

[Ken W]

Scribe it. Hold the new wood block to the transom, and tape a pencil to a 1" block of wood. Follow the transom and it will trace the shape perfectly.
If you have a compass or set of dividers you can use it in place of the pencil & tape rig.