Abstract: A supplemental fluid tank, preferably having two chambers each partially containing a fluid, fluid communicated intermediate a fuel tank and vent to reduce fuel vapor emissions, particularly for a boat. More specifically, when fuel is used or cooled, pressure or volume, respectively, of the remaining fuel in the fuel tank is reduced in prior art systems. Accordingly, air is drawn into the fuel tank through the vent line and becomes saturated with fuel (i.e., fuel vapor). Conversely, when fuel in the fuel tank is warmed it expands and fuel vapor is forced out of the vent into the environment. An exemplary embodiment reduces entry of air in through the vent and escape of fuel vapor out of the vent using two intermediate chambers in fluid communication with each other, each preferably having a non-evaporative fluid (e.g., oil), to provide volume/pressure compensation of the fuel in the fuel tank.

Abstract: A marine vessel overflow tank system for use in the hull of a marine vessel that has a fuel system including a fuel vent line connecting a fuel tank to a vent that communicates with the atmosphere. The system comprises a first vent line fitting adapted for direct parallel communication with the fuel vent line. The internal cross sectional area of the first vent line fitting is approximately the same size as the internal cross sectional area of the fuel vent line. The system also comprises a second vent line fitting adapted for direct parallel communication with the fuel vent line. The internal cross sectional area of the second vent line fitting is approximately the same size as the internal cross sectional area of the fuel vent line. The system further comprises a fuel expansion tank. The fuel expansion tank comprises a plurality of walls defining an enclosed chamber and a first restrictive orifice located in one the walls.

Abstract: A marine vessel overflow tank system for use in the hull of a marine vessel that has a fuel system including a fuel vent line connecting a fuel tank to a vent that communicates with the atmosphere. The system comprises a first vent line fitting adapted for direct parallel communication with the fuel vent line. The internal cross sectional area of the first vent line fitting is approximately the same size as the internal cross sectional area of the fuel vent line. The system also comprises a second vent line fitting adapted for direct parallel communication with the fuel vent line. The internal cross sectional area of the second vent line fitting is approximately the same size as the internal cross sectional area of the fuel vent line. The system further comprises a fuel expansion tank. The fuel expansion tank comprises a plurality of walls defining an enclosed chamber and a first restrictive orifice located in one the walls.