The Northern California Fly Fishing Board

A buddy presented to me his dilemma: the valve on his Wood River float tube or U boat is missing. It is not the typical tire valve, but rather something else. Anyone familiar with this product will know what I am talking about. I am assuming that this company went out of business, so it would be difficult to get a replacement part. Anybody have a solution or source for replacement part to this problem as the fellow prefers to fish this tube over his donut style float tube?

Thanks in advance!!