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Sea toilets


Guest plesbit

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Okay, this may sound like a stupid question, but since Silver Dream had a Thetford C2 toilet from a caravan, we know very little about normal boat toilets but in particular sea toilets.

Ours is a particularly odd setup in some respect, but appears to be fairly normal in other respects. As far as I can tell it has two hoses, connected through the hull, one for drawing in raw water and one for pushing out waste water when the flush is set to overboard. Both hoses have sea cocks. As well as that there appears to be a vent pipe which goes up to an outlet in the hull just beneath the side decks and there is a larger hose for pumping out the holding tank. I've encountered a very similar type of toilet on the Richardsons hire boat San Elena. She had no overboard flush, of course, but essentially the toilet itself looked to be the same - set the hand pump to pump in raw water, pump vigorously, then set the hand pump to drain the bowl and pump vigorously some more. If you're lucky, everything in the bowl will disappear down the hole and into the holding tank.

Okay, so that's the setup, now the questions.

1. Not sure what the rules are governing toilet paper. Don't want to gum up the system! I can think of jobs I'd rather do than having to unblock a sea toilet.

2. What is the story with the sea cocks? Obviously we close them when we leave the boat - but do they need to be closed when cruising? I am sure I remember Rachel (Mrs Antares_9) telling me a sorry story of some foreign "friends" who left the sea cocks open and caused a water spout when Kingfisher was running hard on Breydon. I'd prefer not to experience the same thing. Our surveyer didn't think it would be a problem because he thought the setup of the toilet was different but that doubt has been placed in my mind....

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Hi Simon

In answer to question 1. Toilet paper is designed to dissolve in a very short period of time, I have never experienced a problem. However, we did learn from the mistake of using kitchen roll in an emergency as we run out of toilet tissue. This blocked the pipes very quickly necessitating a rather unfavorable repair.

Question 2. From memory, think providing the pump handle is in the down position Raw water is not able to enter even under pressure. I also understand that the skin inlet and outlets fittings are designed to act as a ventury when in motion, (pardon the pun). To be on the safe side we always left the valve switched to empty to tank as well. We never turned the Sea cocks off on the Princess as they were inaccessible anyway, although we did struggle when we left the boat.

cheersbar

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In answer to question 1. Toilet paper is designed to dissolve in a very short period of time, I have never experienced a problem. However, we did learn from the mistake of using kitchen roll in an emergency as we run out of toilet tissue. This blocked the pipes very quickly necessitating a rather unfavorable repair.

Simple

everything else expands in the pipe thus blocking the pipe up where as toilet roll doesn't :lol::lol::lol:

I learnt that out when using tissues as an emergency :roll::roll:

Jonny ice sliceice sliceice slice

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the trick i found handy when we had a sea toilet on our last boat and becky was younger.

kids tend to use handfulls of the stuff and are more likely to block the system so

i started buying the boxes of soft toilet tissue as they come out one sheet at a time. :naughty:

it saved the job of having to explain to visiting kids.

jill

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cheers Simon! last year when I spoke to someone at Jabsco about fitting one of their toilets and a holding tanks, I was advised to use the cheapest toilet paper I could, as it breaks down and disolves better, so now I only buy budget own brand stuff, a lot of the newer toilets are the twist lock type to stop back syphoning if yours is more than a few years old, you may want to fit an anti syphon loop in the toilet discharge pipe if it dosn't already have one, as for the Seacocks the only time I ever turned them off was when I was away from the boat, a site you may find usefull, flip through it has loads of info,

http://www.tek-tanks.com/sanitation/layouts.html

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cheers Frank, great bedtime reading your toilet link!

Seriously though, a useful link to learn and to look back to. I discovered at the weekend that someone has actually fitted an electric flush to it so you can either pump vigorously with the pump handle or just press a button. Nothing else useful was discovered! ;)

We opened the seacocks both on the flush intake and on the waste water outlet (even though the system is switched to holding tank as we're on the rivers) and closed them again when we left. We didn't sink - but then again we were only doing 6mph. In fact most of the time it was more like 4mph as no-one was in much of a rush.

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  • 4 months later...

Hi Simon, Just found this thread.

You should not need to switch to dry bowl as the idea is that the water coming in on the up stroke is dispelled through the system on the down stroke so you should only be left with the amount of water that you started with in the bowl, leaving water in on the rivers is a sensible option as there is no trap in the bowl to stop the smells from your holding tank just a rubber flap that closes when you pull the handle up to stop it sucking everything from the holding tank up. The same rubber flap should seal if there is presure from outside water to stop that coming into the bowl.

You mentioned a vent pipe, is this from the holding tank? strictly speaking this should be the same size as your pump out hose 1 1/2 " to allow the arobic bacteria to break down what is in the tank withot smelling, it is anerobic bacteria that smells and these flourish when the aerobic bacteria are starved of air.

As already mentioned buy the cheapest home brand stuff going, this is identical to the very expensive marine toilet paper sold in chandlers.

Have never closed the sea cocks on the toilet on Clanny or White Lady while on board, underway the water can be sucked out of the bowl but shouldn't be able to go the other way unless someone has been messing with the rubber seals, they work as flaps closing against their seat when presure is exerted against them.

Ian

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Have never closed the sea cocks on the toilet on Clanny or White Lady while on board, underway the water can be sucked out of the bowl but shouldn't be able to go the other way unless someone has been messing with the rubber seals, they work as flaps closing against their seat when presure is exerted against them. Ian

Not so Ian, if you leave the inlet seacock open and some dork leaves the ITT Jabsco type lavie in pump in mode instead of switching over to pump out there is a direct unrestricted path to the bowl for the sea water. Not much of an issue at river speeds but the pressure generated by planing allows the bowl's transformation to a fountain, how do I know this? some daft sod despite repeated instruction did it and completely flooded the heads before we noticed. Needless to say they were never invited aboard again. The valves are designed to prevent backfow from the outlet side but nor to resist pressure from the inlet side, that's why seagoing yachts have a syphon break on the inlet as most of the time the lavie is below sea level and if not then it can be when heeled on passage.

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A bit more than the shower pump was needed Ian, the heads overflowed into the bilges as well, good job it was only seawater. :o

They didn’t leave the pump handle up, Just leaving the flip switch in the fill position will do it, the flap valve for the inlet side is designed to allow water to flow through the top of the pump into the bowl on the upstroke when the switch is on fill. If you don’t turn the switch which flips a hook under that inlet valve to “empty†holding that flap closed then any pressure generated by planing can force water through the top of the pump and into the bowl. Remember the flap in question is designed to prevent water being pumped back out through the inlet not to stop it coming in, if it were not so then you would never be able to pump water in through it. If you examine the Jabsco manual you will see exactly what I mean. Obvioulsy this will also depend on the position of the water intake, some positions especially further aft may even cause a venturi suction effect rather than pressure.

From the Jabsco site, for below the waterline you can substitute pressurised as it is the same thing effectively.

"SPECIAL NOTE 1: The smaller bore inlet pipework is more hazardous than the larger outlet pipework. Unless there is a ventilated anti-syphon loop in the inlet pipework, water will flow into the bowl whenever both the inlet seacock is open and the rim of the bowl is below the actual waterline.

Although moving the Flush Control Lever (key 23) to the "Shut" position will restrict the flow, this lever CANNOT be relied upon as a shut-off valve.

SPECIAL NOTE 2: Making a loop in the hose without fitting a vent may be just as hazardous as no loop at all, because water may syphon over a loop. It is the vent that actually prevents the syphon."

I was always taught "an open seacock is a hole in the bottom of your boat if it doesn’t need to be on, turn it off", sound advice regardeless of any other considerations.

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You are quite right David,

Now I think about it the water could come in. Then again it was the Raske RM69 that was fitted to both Clanny and White Lady so maybe the design is a bit different., the way that was configured the water was put in through the rim and if the handle was down that would be the only direction the water could go, in order to obtain a fountain the water would have to come up through the bottom so it would have to come in through the outlet, something that the one way valve should stop.

On both of mine the rim was well above water level though and I would think unless you have a fairly deep draught on a pleasure Motor Boat it would be very difficult to set it low enough that it was below the waterline, the toilet is a good 18" high in itself and by the time you are high enough to be out of the V that has to be at least 3'6" from the bottom of the boat. When you are planing you would not have much more than a few inches in the water, so at speed surely it would be even higher.

Obviously the fact that yours did let the water in should be a cautionary tale but I can't work out how it managed it.

Ian

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It can only have been the pressure of water being forced up the inlet pipe by the speed of the boat Ian. A fluid (or gas) passing rapidly over a tube can give one of two effects dependant on the angle of attack, at one angle it will force water or gas up the tube whilst at a slightly different or negative angle of attack it will produce suction using a venturi effect, it’s how water scoops work at the former angle and how say a carburettor works using the latter principle. With the angle of bow up when planning especially with the inlet mounted forward it is presented to the water at an angle that can allow water to be forced up the tube at some considerable pressure. Couple that to the slamming up and down when hitting waves and you have a very effective pump.

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Just noticed this.

For reasons best known to themselves the previous owners of our boat fitted an electric pump connected to the fresh water supply so the toilet can be flushed with a quick push of a button. The manual pump handle is therefore pretty much exclusively in the pump out position, though we have an additional level to select the tank or the hull outlet.

I presume the discharge and intakes have completely separate pipes and therefore a seacock on each? There are two readily accessible seacocks in the locker forward of the heads and on the "if in doubt" basis we have closed both on previous occasions when leaving the boat or running across Breydon. I haven't yet figured out which one is which put presume the larger one must be the discharge pipe.

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Simon

The discharge to sea pipe on our boat is about 2" dia, whereas the inlet is only about 1/2". If you have a valve to select between discharge to sea or the holding tanks, then the sea outlet pipe will be connected to that, so you can tell which is which assuming you can see it!

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Can't see anything Mark. The pipes just emerge through a stiffener from under the heads into the storage compartment. It's not a top concern at the moment anyway - as she's out of the water but it's the kind of thing I will need to sort out ahead of next season.

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For reasons best known to themselves the previous owners of our boat fitted an electric pump connected to the fresh water supply so the toilet can be flushed with a quick push of a button

I would suggest that this was to stop the Sulpher smell you get predominantly in salt water but also in brackish from the lavvy. In this environment the organisms in salt water when left a few days in the inlet break down resulting in a strong sulpher type smell for the first few flushes. A way that this can be avoided is to use fresh water to flush which is what it appears Grenick's previous owners did.

You will have a sweet smelling Lavvy when you venture salt side :grin:

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