I have been reading various posts re: hatch gaskets. Someone recomended neoprene. I just went down to the local dive shop and was told that neoprene has little durability when in an abrasive situation ( where it may be repeatedly rubbed). I am holding my hatches on with shock cord fron the inside and find that I have to slide the lids into position. The cord has to be fairly tight to keep the lid on. Also with the hatches being flush there does not appear to be a lot of room between the lip and the lid for anything very thick. As a matter of fact I will have to sand the lid down between an eight and a sixteenth inch (and reglass)to get them flush in spots, without thinking about gasket thickness. I was thinking maybe a piece of inner tube mounted on the lip and rolled under the lip to give it a bit of spring to seat against the lid. I am wondering what has worked for others?