How should I fill this hole in deck?

[jeffrey.bean]

I removed a 10” inspection hatch, from the deck of my C-Hawk. I want to put in a plywood core and fiberglass over.
How do I support the core, no access inside?
Can I soak to strips of ply with resin, then screw them to the underside of the deck?
Thanks

 

[Scott Danforth]

why not just reinstall the hatch?

 

[Chris1956]

OK, kinda like a drywall repair, but needs strength. OK a dirty idea, assumes a round hatch. Not round would be easier.

Cut a piece of plywood 1" larger in diameter than hole. Cut it in half and install hinge along cut. Drill hole near center and install nylon rope. Now cut a couple of layers of mat to cover plywood, with hole in center to allow rope to pass thru. Saturate it with resin, fold it and put it thru deck and pull it up tight and secure the rope somehow to hold plywood tight to underside of hull. After resin cure, cut off rope flush and fill with plywood plug and glass.

 

[Wildey]

For a very strong invisible patch, bevel the edges, make a matching plug slightly smaller.
Mix some thick PB and gently "bed" the plug till its flush with the deck with a straight edge.
Let it set up then sand it flush, glass it as desired.

 

[jeffrey.bean]

Thanks for the ideas, I think I’ll go with Wildey