Take the foam gasket, peel the backing off the four stickers (this could do with a couple more along the length of the gasket) and place it on the Kayak where the hatch is to go then mark out the pilot holes for the bolts to go through.

Then drill small pilot holes where you've marked & then re-fit the gasket to check the holes are correct. From there you can drill the holes to the proper size (I used a 9mm drill bit)

I drilled holes at each end to make cutting the corners easier and lessen the chances of making a nasty mistake!

Notice the tub of bits, I keep it for plugging any unwanted holes should I ever make a drilling mistake or need to make a repair.

Sorry about the blurred image but I was alone & trying to crack on. The jig saw cut through the soft plastic with ease so be careful as not to wander off-line with it while cutting.

When I got to the corners I cut back over & tried to make them as neat & tight as possible.

I applied a layer of sealant around the hatch to ensure no leakage even though the gasket supplied would probably keep water out.

You can see the wet grab sealant at the bottom of the pic to the right there. It's good stuff but messy & difficult to clean up so have some white spirit & a wet cloth to hand to wipe off the excess from around the edges of fittings.

I've got a fairly new 24v JCB cordless drill (seen left) that was made for industrial work and I used it on my hatch which proved to be a big mistake. The weight of the drill alone is about 5lb's and was too much when coupled with my heavy handedness when tightening a tiny bolt as it pushed the bolt through the plastic, so make sure you use lightweight gear!

I filled the hole with wet grab sealant though & it seems fine & I'll replace the bolt when I have more time.

So there you have it, a fully fitted hatch. Ready for going on the water. All we need now is a good bowl/basin to fit under it to store gear in & keep it dry...