Removing the sea-hood over the companionway revealed an extremely dirty space, clearly never accessed during the 42 year lifetime of the boat. But its all gel-coat so it cleaned up very easily. This part of the deck was dry. I found out why when I drilled out a screw hole to core-bond: its already done! (I suspect the deck prism was also done at the factory since that potentially massive leak area of the deck was also bone-dry.)
The area on the sea-hood where the instrument pod abuts the non-skid shows some stress-cracks in the gel-coat. Since I don’t want those reappearing in my new paint job I decided to reinforce this area. Can’t put a stringer here because of clearance issues, but four layers of ten ounce cloth should do the trick.
The underside of the sea-hood was also super-filthy but being rough layup did not clean easily. Formula 409 cleaner was only marginally effective, as was Interlux Fiberglass Solvent Wash 202. The area surrounding the new glass shows how well they worked: still darkly stained. Good old MEK (methylethylketone) did the trick, however. I also abraded the area with a rotary Scotch-Brite disk before laying in the glass.
On the rest of the deck I got rid of the old non-skid by simply sanding it away. Its composed of gel-coat, not fiberglass, so adds little to the strength of the deck. But here I didn’t want to weaken things at all so decided to fill and fair the area instead. Before sanding.