Kayak Hatch Cover Oval Valley Sea Kayaks In the 1980's Valley became the first company to develop a watertight hatch system especially for kayaks. Although other companies offer similar products, their original system remains the benchmark by which these other systems are judged. Strong yet supple polywhatsit rubber creates a reliable seal with easy access. This is the oval replacement hatch cover for Valley Sea Kayaks. This oval cover is also used on many other manufacturers kayaks including Current Designs, Necky, Impex and Wilderness Systems.