A valve structure includes a valve body on which is mounted a first valve and a second valve. The first valve traverses the valve body at a first position and the second valve traverses the valve body at a second position spaced apart from the first position. The first valve may comprise a fill valve and the second valve may comprise a pressure relief valve. Alternatively, a single valve structure may incorporate both the fill and pressure relief functions. The valve structure may be incorporated with a bladder made of a flexible and elastic material. In this arrangement, the valve body is positioned in a valve receiving opening in the bladder material and is sealed to the bladder material around the periphery of the valve receiving opening so as to define a sealed bladder interior with the bladder material. Such a valve and bladder combination may be used together with a hull tube to form a portion of an inflatable hull for a boat.