Here's a link to the deck plates. I didn't get mine at Boatersworld, but they're the same plate.

What I did was take off the hatch cover and cleaned them. Applied a thick bead of rule around the inside of the hatch (to use as a gasket) and let it set overnight. I then mounted the deck plates and reinstalled the hatch adding extra screws. After tightening everything down, I ruled completely around the outside of the hatch. So far so good.

I had a difficult time with the screw on type plates because my hatch covers were not perfectly flat. This made it very difficult to screw the deck plate covers on and off and I think this is what caused them to leak.

Good luck with your mod!

http://www.boatersworld.com/product/166610451msk.htm