lewmar hatch leak - mounting a new gasket

In the summer 2017 I sealed the hatch with some butyl sealant and sikaflex 295 UV but the humidity levels are now to unevenly so I change the rubber gasket to a new one.
This is the first time I do a hatch gasket change so I don't know how tight it must be.
After completion of the filming and editing I plan to make it more tight so the gasket will hold it self on the acrylic glass plate.
I have measured the old gasket and it is 188 cm. long.
The glue I used is Loctite ALL PLASTICS : www.loctiteprod...
Rubber gasket : www.svb.de/de/...
Rubber for one hatch : 38 US Dollars
Loctite all plastics glue : 11 US Dollars