: On the side of both bow & stern hatches furtherest from the cockpit I'll
: epoxy a wooden finger to hold that side of the hatch in place.

I think two wooden fingers, each about 1/3 of the way across the hatch would be better, safer.

........ A longer length of pvc pipe will be epoxied to the underside
: of the deck in line with the 1st & will extend thru the bulkheads to a
: point just short of being visible in the cockpit. through this pipe I will
: insert a dowel rod.

Instead ....How about two pipes, again located about 1/3 of the way across , containing much much shorter (6") dowels , each spring loaded with bungee cords... to force them into the PVC ... and a line led back to the cockpit which is pulled to bring the dowels back to clear the pipes. a small plastic jam cleat in the cockpit area could hold the cord when you want the dowels retracted to open the hatch. Say one inch PVC on the hatch, 4 inch PVC as a guide for the dowel, and 6 inch dowels , , long enough to get some pressure from the stretched bungee cord.

I guess I do not wear both belts and suspenders, but with something as critical as hatch covers. LOL I might.

I want redundancy, and absolutely firm closure on both left and right sides of the hatch lid curved covers. I would also worry about a long dowel all the way back to the cockpit breaking, or jaming in the PVC pipe with sand or dirt .... hence two wooden fingers,and two dowel /PVC pipes . As well, careful slant cutting the one inch hatch pipe, and the dowel ends might make it possible to "snap" the hatch closed from the outside..... maybe ...

But its all just a matter of engineering refinements.

Its still a fantastic idea .. Congrats !!!!!!