Sink trap (gray water setup)

[wkearney99]

Are there any traps available for marine sinks? My existing setup drains two head and galley sinks into gray water tanks (along with two shower drains). The sink levels are nearly at the waterline, thus it's impractical to run them directly overboard.

We use the boat recreationally, so there's sometimes enough 'down time' to allow the gray water tanks to get a stink going. The result is a musty smell coming up from the sink drains. This was made worse last week by discovering one of the gray water tanks had overflowed due to a failed float switch (typical Rule float switch unit).

It seems like a trap would be a relatively simple fix, in that it'd provide a water trap to block the stink. Although, with Whale gulper pumps emptying the sumps I suppose there's a risk they'd get pulled dry. The gray water sumps aren't vented. I'm thinking that there should be enough available air from the shower drains to avoid added traps being pulled dry.

 

[FoxtrotCharlie]

I would think regular home/HD or Lowes/Ace p-traps would work. I would probably use the 1 1/4" size to save a bit of room. Should be a relatively easy job. Yep, that Gulper may pull the water out, but as you said, the shower may provide enough 'air behind water' - or you could just be mindful and run some water and refill the traps. Good luck.

 

[ben2go]

If you have standard 1.5 inch home drains in your sinks, then using a standard or deep P trap would work well for you, I would think.


This flexible Snappy Trap could be your answer. The corrugated tubing is smooth walled inside so no worries about trapped soilds.


https://www.amazon.com/Special-Vert...1913d3d3487b36ccd15258b6fa134d&language=en_US

 

[FF]

Plan B might be to simply vent the tank to get the smell outside.


Although plastic P traps are cheap and work well.

 

[ben2go]

Plan B might be to simply vent the tank to get the smell outside.

That's true but I was under the assumption that the tank was vented. Ya know what "they" say about ass-u-me ing things.

 

[FF]

"That's true but I was under the assumption that the tank was vented."


Vented to allow water to enter the tank (tiny) and vented to allow smells to depart would be different in size.

 

[psneeld]

Shower and drain sumps usually don't need to be vented as there is no vacuum to pull against as the drains are open to the atmosphere.

 

[koliver]

A regular Rule float switch? A non vented tank with that float switch inside? Something else? How do you get at the float switch?

My aft head sink is on centerline, so it and both showers drain into a sump in the bilge. That in turn is emptied with a Rule pump activated by that regular Rule float switch. It gets enough flow from the three inputs so the water gets pumped out before any stink develops. It is also small enough that only a cupful of water remains after pumping. There is no top on that sump, except that it is covered by one of the bilge floor boards. If it ever overflowed it would be pumped by the fwd bilge pump.

 

[wkearney99]

A regular Rule float switch? A non vented tank with that float switch inside? Something else? How do you get at the float switch?

My aft head sink is on centerline, so it and both showers drain into a sump in the bilge. That in turn is emptied with a Rule pump activated by that regular Rule float switch. It gets enough flow from the three inputs so the water gets pumped out before any stink develops. It is also small enough that only a cupful of water remains after pumping. There is no top on that sump, except that it is covered by one of the bilge floor boards. If it ever overflowed it would be pumped by the fwd bilge pump.

Which is how quite a few (most?) sump/bilge setups are arranged.

What I've got are two Whale gray water sumps, older models that are just gray poly with round white inspection hatches. The are not vented. Inside each is a Rule-a-Matic 40A switch (the rectangular kind, not the open paddle type). These trigger Whale Gulper pumps.

Replacing the switch was a simple matter of opening the inspection hatch, unscrewing the stainless nut holding it down and threading the wires out of the tank top. Replacement was likewise simple, just splicing the new one back into the existing wiring.

The float inside one died, resulting in that sump overflowing (by forcing water out of the lid). Which, in turn landed in the bilge below which, like many, never pumps 'entirely' dry... leading to stagnant waters from sinks causing a stink.

Looks like Ambassador has some traps that could work in my situation.

Drains

I'd replace the existing flange/tailpiece under the sink itself. Their flip-up variation would eliminate the need to keep the stopper on a chain (or scramble to find it later).