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LittleWingCA 09-16-2010 03:31 PM

Shower Sump Thru-Hull
Hi Everyone:

While gathering information on a toilet problem posted in another thread, I noticed while fishing around the plumbing of my toilet, that the hose from my shower sump pump to the exit thru-hull has no seacock on it as it exits the hull. :eek: I was quite surprised to see that. Not sure how I missed that. The hose just connects to a 90 degree elbow that attaches to the thru-hull. While the thru-hull sits at the water line mark on the hull, and due to my normal slight starboard list, sits above the water while not sailing, it certainly is below the water when on a port tack with any kind of slight heal. There is a service loop in the hose run that probably keeps the entire hose assembly from being completely below the water, and the pump is up high well above the water line, but the pump is the only thing between the open sea and the shower pan drain. :eek: There isn't an anti-syphon valve on it either. I can't believe this is normal / acceptable???

In this case, given the tight constraints, ( it is behind a toilet paper storage bin) is it adviseable to add a proper seacock to the hull ( would need some kind of 90 angle one ), or given its function, just a ball valve attached to the elbow coming off the thruhull?

erps 09-16-2010 04:01 PM

I think your instincts are good. Plan for the worst case senario and put some sort of a shutoff valve in any hoses going overboard. We have a sink in the head that we have to shut off when we're sailing hard because the sink goes below the waterline when we dip the port rail.

oceanscapt 09-16-2010 05:15 PM

I'd install a sea **** even if you have to go with a gate valve (as opposed to a ball valve). If you have to use the 90 elbow, that's what you have to do, but I'd think that sharp a bend might lead to problems (blockage?) down the road.

LittleWingCA 09-16-2010 05:17 PM


Yea, I have a proper seacock on the sink drain in the head for this reason, but was shocked to see the shower sump didn't have one, even though the exit is at or slightly above the waterline depending on list. I have also heard that anti-syphon valves are good to have until they fail open, and act as a leak source, so I guess it depends on preference. I might have to add a anti-syphon and a shut off of some sort.

LittleWingCA 09-16-2010 05:20 PM


Yea, my preference would be a proper seacock, but I don't know if I can find one that will fit the space. I have to do some looking. As a short term fix until I haul out for my next bottom job, I should at least put a shutoff valve in as a minimum or cap the thruhull since we don't use the shower.

erps 09-16-2010 06:01 PM

Can you T-into the sink drain?

Sapperwhite 09-16-2010 06:14 PM


Originally Posted by erps (Post 644692)
Can you T-into the sink drain?

this is what i have on Jessica Anne. The shower sump is Tee'd onto the head sink seacock. The only problem if you do that is what to do with the old hole in the hull.

LittleWingCA 09-16-2010 06:18 PM


Technically yes, but I wonder if that is wise? Is there a reason shower sumps are plumbed out above the water line? Since the shower pan drain is lower than the thru-hull, that could be another failure point since you might want the sink drain active but not the shower when underway and healing. Hmmmm. Not sure but my gut says that may not be a good idea either.

Sapperwhite, have you seen any issues when underway and the sink drain open? I would worry about that being a ingress point if the shower pan was lower than the seacock, even with a long service loop of hose. I guess you can cap off the old thru-hole.

Sapperwhite 09-16-2010 06:28 PM

my shower sump has a large loop that goes above the waterline to prevent back flooding. also, in all honest, i never have the head sink seacock open. if i need it for the shower i open it then and reclose it immediately when done.

i don't use the head sink, i brush teeth in the galley sink, wash hands in galley sink, etc etc etc. the head sink gets zero use. i would remove the head sink if i didn't think it would hurt resale value.

Also, a concern of yours about the Tee being a failure point. When i said mine was tee'd i wasn't being exactly truthfull. It's not a simple Tee fitting. I have a 3-way ball valve mounted atop the seacock. with the 3way ball valve in position 1 the sink drains to the seacock. in position 2 the shower sump drain to the seacock. No two can be lined up at the same time.

Its not the best system out there, but it isolates one drain from the other, and if there is a problem with both, i can just isolate the whole damn thing with the seacock.

WanderingStar 09-16-2010 06:31 PM

Interesting, I recently had the same experience. I'm doing head plumbing and my shower/sink discharge has no valve. I think I'll add one too. Though cutting the sink hose showed me how strong this stuff is. It's rubber, two layer, (red outer, black inner) with fiber between. I had to saw through with a serrated rigging knife.

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