I am replacing the fuel lines on my SL 780 and was looking at a fuel system schematic. I noticed that there is a tee fitting on the fuel tank vent. One is the air out and the other is the air in that connects to the tee fitting. I do not have a tee on my ski with the air in line. The schematic says its attached to the hull air intake duct. I am just wondering where this line connects. What does it mean connects to hull air intake duct?