I think this question was answered, but I would like to confirm. There's no good reason to have a sag (or two) in a freshwater tank vent line, is there? We scrubbed the tank on a new (to us) Y33, and found water and sludge in the vent line. It shouldn't be too hard to straighten out, but thought I'd check before performing surgery.
A low spot in the line will allow water (or fuel or the other stuff) to collect in the line, effectively sealing the vent. Think of the trap under the kitchen or bathroom sink. The trapped water will allow stuff to grow and in the case of the holding tank, plug it up and permeate the hose adding to the smell.
Water enters the trap because the tank will get over filled or it is filled to capacity and the action of the boat sailing causes some water to get into the vent hose. Or, if the tank is filled with cold water and it warms, the expansion will cause the tank to overflow into the vent.
I couldn't have said it better...except maybe to add that it's a good idea to have an ARCH in fuel and water tank vent lines to prevent sea water from contaminating them if/when you're heeled enough to put the vent under water for more than just a brief dip. Holding tank vent lines should be as straight as an arrow...no dips OR arches.
Thanks Miss Peggie, I've been studying, even spelled your name right.
While I have your attention, what's the hose diameter on a PHII from the pump to the bowl. I forgot to measure it last fall and I want to install a vented loop.
what's the hose diameter on a PHII from the pump to the bowl. I forgot to measure it last fall and I want to install a vented loop.
3/4", same as the hose from the thru-hull to the pump.