Originally Posted by SlowButSteady
If the vent line actually runs down and then up it essentially forms a "trap". Any moisture inside will pool at the lowest point and prevent air from getting through, hence the stink. I would re-route the line so that it has no low points. I would also install a second vent in the tank. A single vent will only act to equalize the pressure between the tank and the atmosphere, with little or no circulation. This results the tank becoming anaerobic and stinking. Having two vent lines, with their exterior fittings located as far apart as practical (for a slight pressure differential), will allow for exchange between the tank and atmosphere, and help to keep the tank aerobic (and MUCH less stinky).
I like the idea of two vent lines.
with the holding tank in the v-berth, my only real option to go up is to go forward. I just wonder what effect that will have those few times I bury the nose in the water. Is that going to fill my undersized 12gal holding tank?