: Thanks everyone. I'm fairly limited with the tools that I have (no router, no
: "sander spindle").

Hi Doug,

My 2 cents [a bit late maybe :-)]. I drew the patterns on one piece of ply (inside, outside and coaming lip lines) and srewed 3 pieces of ply together. Then cut the outer coaming lip, then inner cutout. Took off the bottom piece of ply 9so I had 2 still screwed together) then cut the outer ring (i.e. cut off the coaming lip on these 2 bits, down to the smaller outside dimension).

I cut out with a jigsaw, then screwed the three back together and sanded the inside with asanding drum attachment on my power drill (you can usually get sets of different sized drums from tool shops, just slip on sandpaper sleeve and chuck in drill, you have a spindle sander).

Outsides I sanded with a detail sander (small random orbital one) and they all came out neat and the same size. You can use the sanders to round over the coaming edges too.

Hope this helps (and the explanation makes sense).

Regards,
Darren