Hi there,
This is not house related but rather boat related. However with a bit of luck the question is generic enough that it might find an answer here.
I am currently re-bedding the deck hatches of my boat, as they are all leaking. The hatches consist of a square aluminium frame on which the hinges and then the hatch panel are mounted. The alu frame is then mounted on the deck on top of a wooden frame. The frame is epoxy-glued to the deck. The whole assembly (alu frame, wood frame, deck) is then thru-bolted.
The leak happens to be between the wooden frame and the deck. So I am rebuilding new frames using plywood (2x12mm) glued with epoxy.

The problem is, the deck is not flat (of course). I need to trim the thickness of the frame so it sits flush on the deck. I made a template in MDF of the curvature of the deck. I need to remove about 12-15mm of thickness in the center of the frame.
How would you approach that? Sanding? Planing? using a router? a jig-saw?
Many thanks in advance for any advice!
Antoine - Berrimilla 2