Goose neck

A goose neck is the inverted-U bend at the top of a tank air pipe or vent, shaped so the opening faces downward to keep rain, spray, and green water out while letting the tank breathe as it loads and discharges. Air pipes from fuel, ballast, and water tanks on the weather deck terminate in goose necks fitted with a flame screen and, where required by the load line rules, a float-type automatic closing device to stop downflooding. The goose-neck height above the deck is set by the Load Line Convention. The same term describes the bent neck on certain crane and davit fittings.