I've paddled Valley boats for about 15 years now. I have had a pretty decent experience with their hatches, though I do seem to get random leaking some days. I seat the covers the same each time, snapping the cover down and then carefully seating the lip into the well between the hull and the recessed coaming flange. I usually give the whole hatch cover a solid twist back and forth to make sure it is seated in its 'lowest energy state' or basically where it seems to be mated the best with the flange. Some rough days not a drop gets in, but on other days punching into a steep wind chop I may get multiple cups of water into the compartment. My Valley hatch covers last for many years since I store them indoors in the winter and I treat them with some UV protectant once or twice a year. The random leaking annoys me though. My stuff is protected in dry bags, but still, a leaking kayak sucks. I just ordered some Sealect Designs hatch covers as they are billed as being direct Valley replacements. I got two ovals and one round to replace all my Nordkapp covers. They all pop on very easily and are a joy to remove. The construction looks super. I tried a garden hose spray test on the oval (Sealect #K745170-1) and was really disappointed in the results however. After about 30 seconds of a solid stream of water pointed at the juncture between the cover and the hatch coaming (no spray nozzle, just an open hose emitting a strong stream), I got significant water in the compartment. The hatch cover seems to rotate a few degrees suspiciously easily when I try to spin it when installed. I made sure it seemed to be centered in this range of rotation when I tested it. I put my Valley hatch back on the usual way and did the hose test on that cover too. The boat was dry inside. I tried the Sealect again and got significant amounts of water in once more. The hatch cover is definitely fully seated all the way around, so it's not a matter of incorrect installation. Being advertised as a direct Valley replacement I figured the Sealect coamings must use the Valley dimentions, but maybe they are slightly different and the Sealect covers work better with the Sealect coamings. Maybe not. Has anyone had experience with these things? Eddyline boats seem to use these hatch covers as do some other manufacturers, presumably with the Sealect-made coamings. Do they preform better on Eddyline et al boats? At this point they seem to be pretty inferior to the stock Valley covers and I may return them unless something improves dramatically.