Sea toilet sea cock. Open or closed when underway? Daft question time!

[Sneds]

We have a new, to us, Sealine F36 with Jabsco manual sea toilets and no holding tank (yet)
That's not the problem as our mooring spots are well served by convenient conveniences!
My question is this,
Should the inlet and outlet sea cocks be closed when underway?
Can the sea come up the pipe from outside and come into the toilet bowl and potentially flood the boat?

 

[Seashoreman]

I have a Jabsco and only shut the cocks when leaving the boat unattended on the mooring for a few days.
Certainly never experienced problems when underway, no matter what the conditions.

 

[Montemar]

We have never bothered to close off any seacocks. Have not had any problems with it.

 

[[2068]]

I tend to keep the seacock for the holding tank discharge closed, unless discharging.
At least this way it gets moved a few times each season.

 

[Sandyman]

Its HEADS bloody heads, not bloody sea toilet.

 

[rafiki_]

Its HEADS bloody heads, not bloody sea toilet.

No need for that. Sneds was seeking clarification, and therefore giving detail that we can all understand.

 

[prv]

The toilet has two valves inside the pump which should stop major surges of water. They're not 100% effective though, and in any case are only made of thin rubber, so you shouldn't rely on them to keep the sea out long-term.

If the toilet is mounted well above the waterline then you should be fine - the water won't climb up the pipes for no reason. If the toilet is below the waterline, then it should have been installed with the pipework looping upwards well above the waterline, so that again the water would have to climb upwards (which it generally doesn't) to get into the boat. The slight wrinkle here is that it can siphon over a closed loop if something starts it moving, so there should be a valve at the top of the loop to let in air and prevent siphoning.

Some toilets are installed incorrectly, below the waterline without loops or with loops but no siphon-breaks, and then they can back-flow into the boat. This is obviously dangerous and should be fixed, but some people seem to be willing to live with it and just close the seacocks instead to work around the problem. Coupled with the early days of boat plumbing in lead and gutta-percha and whatnot, when pipes breaking was actually a real risk, and we get the idea floating around people's heads (no pun intended ) that valves need to be opened and closed all the time as if we were living in submarines.

(One caveat here - I'm a sailyboat person and not particularly familiar with the dynamic effects of fast motorboats. But I'd still consider a toilet installation defective if it needs valves to be manually closed or risk sinking the boat.)

Pete

 

[ari]

Its HEADS bloody heads, not bloody sea toilet.

My understanding is that 'heads' refers to the whole toilet compartment. In the OPs 'heads' he has a sea toilet which he is asking questions about, so seems to me he's right to use 'sea toilet'.

 

[ari]

And to answer the question, the sea toilet in my heads seems to fill with water underway even on 'dry bowl' so I always close the sea cocks underway.

 

[Mr Googler]

This wot happens when lounge dwellers venture here

Its a bog or lav on our boat!

Good thread though, im going to check my pipe runs tomorrow as i just replaced my loo and didnt see an upwards loop. Need to get a tape measure to see how high it actually is above the water line. Thanks sneds.

 

[[2068]]

Its HEADS bloody heads, not bloody sea toilet.

Hardly any pages show the device in question referred to as "Jabsco Manual Heads".

 

[A_8]

You should definitely close them underway particularly if you don't have a holding tank connected. I would not be surpriced if that is part of the safety instruction for the boat, it was on mine, big sign on the wall.

It was properly installed and on several occations I forgot to close it and it filled up with seawater. Particularly in large following seas at speed, surging down into the next wave would pressure water up through the piping.
If a holding tank is connected the water first fills the holding tank and most likely you won't notice or if its full it will be pushed out through the air drain.

 

[Sneds]

Interesting answers, on both topics!
��

 

[rafiki_]

We don't close ours underway, and have had need to use them on a long passage. Ours are the Sealand vacuflush sea toilets.

 

[KINGFISHER 8]

Thunderbox.

 

[syc1]

big sign on the wall.

Go on then I can't resist:

It's BULKHEAD, bloody BULKHEAD, not wall!,

 

[David2452]

We had visitors who left the Jabsco manual toilet valve in the fill position after use and the pressure of water whilst on the plane caused quite a bit of flooding before it was noticed, we no close the valves and check the lever is in the discharge position.

 

[vas]

You should definitely close them underway particularly if you don't have a holding tank connected. I would not be surpriced if that is part of the safety instruction for the boat, it was on mine, big sign on the wall.

It was properly installed and on several occations I forgot to close it and it filled up with seawater. Particularly in large following seas at speed, surging down into the next wave would pressure water up through the piping.
If a holding tank is connected the water first fills the holding tank and most likely you won't notice or if its full it will be pushed out through the air drain.

sorry but doesn't sound right to me!

so on passage, you want to use the toilet you have to:
A. stop
B. lift carpet (if fitted), lift hatch underneath
C. turn the seacock (or seacocks in which case I sincerely hope they are nearby!)
D. use the toilet (hope you don't have to refit hatch and carpet in order to open and close heads door etc)
E. do the same lot again
F. start the engine and go on

And you don't think that's something wrong in the way someone fitted that lot then?

Funny as I was about to ask a similar question (might as well do it here if you don't mind )

jabsco style el. seawater toilets (x2) above waterline
108lt black water tank (below waterline)
massive 1.25inch diaphragm pump on the verge of being above the w/l
loop above waterline between tank and pump
Trudesign 1.25inch seacock by the keel (blackwater tank discharge)

Question is:
Should I leave the seacock open at all times (when I'm on board that is, not over winter...) or should I just open it for emptying?


cheers

V.

PS. shit shouldn't be able to push up through the air drain as A. should be relatively high B. there's a carbon filter somewhere in between which I'm not sure is happy to let fluids through it...

 

[A_8]

sorry but doesn't sound right to me!

so on passage, you want to use the toilet you have to:
A. stop
B. lift carpet (if fitted), lift hatch underneath
C. turn the seacock (or seacocks in which case I sincerely hope they are nearby!)
D. use the toilet (hope you don't have to refit hatch and carpet in order to open and close heads door etc)
E. do the same lot again
F. start the engine and go on

And you don't think that's something wrong in the way someone fitted that lot then?

Funny as I was about to ask a similar question (might as well do it here if you don't mind )

jabsco style el. seawater toilets (x2) above waterline
108lt black water tank (below waterline)
massive 1.25inch diaphragm pump on the verge of being above the w/l
loop above waterline between tank and pump
Trudesign 1.25inch seacock by the keel (blackwater tank discharge)

Question is:
Should I leave the seacock open at all times (when I'm on board that is, not over winter...) or should I just open it for emptying?


cheers

V.

PS. shit shouldn't be able to push up through the air drain as A. should be relatively high B. there's a carbon filter somewhere in between which I'm not sure is happy to let fluids through it...

My experiance is from a CE Cat B boat and a very std install, optional with and without holding tank and nothing wrong with it. I could switch between direct discharge or to the holding tank. The op has a manual jabsco as far as we can tell and without a holding tank which I am familiar with and simply sharing my experiance, really not interested in understanding your setup.

Normally it's a non issue and they can be open but when the weather gets bad and the waves grow big you will get water pushed up through the piping and the valves won't be able to withstand the back pressure fully. For those who don't believe me ask what the the rag and stick guys with same setup do when the wind gets strong and the waves grow big.

Consider this, you cruise in following seas and hit a 2 m wave at 17 knots and the bow is almost submerged for a bit, the head compartment and valves are in the front of the boat. Will the joker valve and whatever else is in there be able to withstand the backpressure fully?

I am sure Jeanneau put the warning sticker on the BULKHEAD just for fun, why not add an extra €30 becouse they could...right? Beeing a low cost brand and all.

If there is a holdning tank its less likely to be an issue and if you shut off the discharge valve from the holding tank you will be secure and also be able to use it.

 

[prv]

And to answer the question, the sea toilet in my heads seems to fill with water underway even on 'dry bowl' so I always close the sea cocks underway.

If it's the normal Jabsco toilet then putting the lever to the "dry" side won't do anything to stop that anyway. All the lever does is jab a little plastic finger into one of the valves on the "flush" side of the pump, holding it open so that the pump no longer functions. Then when you pump, the amount of water sent into the bowl is much reduced (not usually stopped fully) - but if the water is being pushed in from outside for some reason, it will still flow. In fact if anything, the valve held open will make it easier!

Pete