Here I get help of Stefan to grind the coamings flat.that will take the hatches, more precisely the gaskets of the hatches. The bottom of the  holders of the gasket is also flat bebouse I have poured NM-epoxy into it. Thus agot two very flat matching surfaces. That will make a thight hatch.

The hatch and the rim that will hold the gasket. Into the rim I have poured NM-epoxy that makes a leval surface.

To be continued…

Regards Yrvind