Normally bilge areas are connected by pvc type piping. On inboard models, there should be two pipe outlets coming through bulkhead into engine bilge area. One is from forward bilge area, and the other from fuel cell compartment. NOTICE that pipe coming from fuel cell compartment comes with removable plug on small chain that should be installed before running engine. This way, any possible leaking fuel or vapors from fuel tank will not enter engine compartment. At least that was the theory when they built them this way.