Front hatch install

I have a Cobra Fishing Navigator. I recently was gifted a large "triangular" front hatch for it like the one that comes on the front of the tourer. There is a fair amount of curve to the bow and I'm hoping you guys can share insights or previous threads on how to make sure I install it correctly. I heard weatherproof material used as a seal to compensate for any surfaces that don't flush mount?

I appreciate the wealth of knowledge!