Give me the poop on my vented loop

[Seattle Scott]

I have a starboard side head with the holding tank a foot way with no Y valve, all waste goes into the tank. After the tank the waste hose has a Y with one hose going across the boat to the port side deck pumpout and the other hose going across the boat, up to a vented loop and down to the manual pump and then to the through hull with ball valve. The vented loop and the deck discharge hoses (3) all ran through a hanging locker on port side ( remember head and tank are on starboard). When the hoses started stinking I starting thinking. I don't need a vented loop because the through hull value is only open when pumping overboard, which is rare, so there is not going to any unattending syphoning. So ( with new hose) I re-routed the deck discharge to starboard right above the tank and took out the whole 8 feet of vented loop hose. Then I put an inline valve at the tank exist collar, which I keep closed to keep poop from sitting in the hose. immediatly after the inline valve is a Tee with one line going to the deck and the other to the manual overboard pump, with the pump being 6 inches above the water linem then down to the through hull. The pump and through hull valve are in the same locker.So when I have the boat surveyed before year end for insurance renewal, is the surveyor going to say, put the vented loop back in? Everything smells sweet, meaning everything does not smell, and that is swell.

 

[Peggie Hall HeadMistress]

The answer to your question: most likely yes

If the surveyor is compentent. An incompetent one will prob'ly let it pass. There are more incompetent surveyors than competent surveyors, so the odds are better than 50-50 in your favor. But if you want to do it the right way anyway, the vented loop was in the wrong place...it belongs between the the pump and the thru-hull.I got lost in your description of the rest of the plumbing. Nothing about it seems to make any sense at all!

 

[Richard19068]

Thanks Peggy

I thought I was dense trying to understand what he was saying. I just thought to myself " Peggy will know what he's talking about".

 

[Seattle Scott]

Hey I resemble those remarks.

OK Peggie was right, the old vented loop was between the overboard pump and the thru hull. So here is a "precise" question: If there is no possible way to directly over board discharge from the head, why do I need a vented loop downstream from the holding tank, since the thru hull is closed except when pumping the tank overboard?

 

[Bill Roosa]

You don't

Hydrodynamically speaking your estimate of the plumbing is accurate. With that said the next guy will not have a clew and leave the thru hull open all the time and dump black water into the bilge. While you can get away with it other folks are not as able bodied seaman like.You could get around the whole issue by dumping to a thru hull that is above the waterline. Then you only have to make sure the boat is heeled enough to submerge the thru hull. This would aid the draining of the tank too. ;-) I would not try this solution for a live aboard however. ;-) ;-)

 

[Peggie Hall HeadMistress]

Bill is right...

IF you're infallible and never leave the seacock open, you could get away without the vented loop. But humans are not infallible, and as Bill pointed out, the next owner may be a doofus who's too lazy to bother with opening and closing seacocks. So if you're gonna err, do it on the side of caution...you can never go wrong doing it that way.Although I'm definitely NOT a fan of above waterline sewage discharge thru-hulls, I wonder why Bill thinks it's an even worse idea for liveaboards...'cuz I can't imagine there are very many liveaboards anchored outside the "3 mile limit," so he must be implying that a lot of liveaboards are dumping tanks illegally.