[C320-list] Head smell discoveries

[Jeff Hare]

Hi,

We have hull #809. Flush with fresh water and only this season after commissioning had bad smells whenever the head was flushed. Even after just one pump.

Pulled the medicine cab, opened the compartment with the holding tank and started experimenting. 

Poured a gallon of fresh water in and pumped one time. The first area to stink was behind the medicine cab. Nothing smelled near the tank itself and the hoses themselves didn't smell. 

From behind the med cabinet you can very easily reach the vent fitting. It wasn't very loose and the hose didn't seem to be loose either but showed minor signs of leaks. I should add that our vent is the small black capped version, not the chrome fuel vent style. 

The inner nut holding the vent in is quite unusual and looks more like a 2" plastic jar lid with a threaded hole in the center. But it can't form any real seal with the rough fiberglass wall. The outside has a plastic washer but barely covered the entire hole. So, long story short, because of the covered cap, the vent was venting gasses back towards the boat, but since there wasn't much of a seal it was blowing back inside the boat a little. 

To make matters worse, the hose is about 1" OD/ 3/4 ID but the vent fitting is only 1/2", so they stuck a smaller diameter hose inside the large hose and clamped them. I bet that was part of the problem.

Anyway, with the new vent hose left long and fed out the head hatch for testing, pumping the head left no smells inside the boat anymore. (I heard the neighbors running away outside however :)

So the question, can I just use a small open thru-hull fitting here that has a 3/4" opening (kinda like the propane or cockpit transom drain) so that I dont have to mickey mouse the hose fittings? I can't find anyone that makes a thru hull fuel vent larger than 5/8".

The only downside I can think of offhand is bugs making nests in there. There may be screened versions.

Thanks for any insight here. The boss said fix it. My suggestion of a new boat wasn't the correct answer apparently so now i'm asking you guys. Get me out of jail. 

--jeff