Seacocks

[Peggie Hall HeadMistress]

I suggest the twist lock prevents siphons from both inlet and waste lines. Why?

The motive forces for inlet sea water and exit waste is started by the pump and can continue if siphon breakers don't work. Locking the pump stops both siphons. The high point loops prevent back flow and so do good sea cocks.

Nope....Doesn't work that way 'cuz the intake line isn't connected in any way to the discharge line. The intake pulls water to the top of the pump and pushes it into the bowl via inlet fitting at the top of the back of the bowl.--which doesn't actually start a siphon...the intake line on a below-waterline toilet just provides a path for water outside the boat to seek its own level INside the boat.) The pump pushes bowl contents out the discharge at the bottom of the pump...that does not start any siphon either. Bowl contents will continue to move through the discharge line only as long as the pump is pushing them or gravity takes over. Those two functions are totally independent of each other. You can stick a plug in the discharge fitting, and the pump will still bring in water in the wet mode...you can also close the intake seacock and the pump will still push bowl contents out. Vented loops are just air breaks, they don't prevent backflow.

I like it because once the flows stop, siphon break plugged or not, i statically secure my inflow line from continuing to fill bowl.

Sorry to burst your bubble, but you don't. The only effect that securing the pump has on the intake is to make it impossible to operate the pump, thus makingi it impossible for YOU to continue bringing in any flush water. It can't stop any flow that's already started or prevent new flow from starting. A siphon break (vented loop) can't prevent any new flow from starting either, but it CAN interrupt the flow started by priming the pump with an air break that stops it.

 

[JamesG161]

Nope....Doesn't work that way 'cuz the intake line isn't connected in any way to the discharge line. The intake pulls water to the top of the pump and pushes it into the bowl via inlet fitting at the top of the back of the bowl.--which doesn't actually start a siphon...the intake line on a below-waterline toilet just provides a path for water outside the boat to seek its own level INside the boat.)

Nope. Not on my boat.

You all should make sure of your Head design. This friendly discussion does point that out.

Below picture is from the Jabsco manual and it what i have my boat except I have a hold tank and not a direct shot to the water. My boat would flood if I didn't have a high point loop on the inlet. Hmmmm I wonder why they have siphon breaks on each loop?
Take care...
Jim...

PS: Passes all a schooner of beer or favorite adult beverage.

 

[Peggie Hall HeadMistress]

ALL below-waterline toilets, manual and electric, should have a vented loop in the intake...and I do hope you paid enough attention to the instructions to put it where it belongs and NOT the line between the thru-hull and the pump. The illustration includes a vented loop (siphon break) on the discharge line because that discharge line is connected to a below-waterline thru-hull...a safety standard that applies to all hoses connected to below-waterline thru-hulls, but not needed in systems that flush only into a tank.

Are you sure you want to keep trying to tell an ol' gal who spent 25 years taking every marine toilet ever made apart and putting 'em back together for a living how they work? If you are, by all means keep trying...you'll learn something new each time.:dance:

 

[VF84Sluggo]

Are you sure you want to keep trying to tell an ol' gal who spent 25 years taking every marine toilet ever made apart and putting 'em back together for a living how they work?

Better you than me...so I for one am darn sure willing to take your word for it!

 

[woodster]

If you put the siphon break in the sea water intake line to the pump it will not pump water from the outside water it will only suck air the membrane opens up and let's air in the line and will not pump The only place the anti siphon will let water through is when it is being pushed by the pump (not pulled by the pump)

 

[Lodi47]

Well, this is the last thing troubling me. I bought a 1978 Spirit 23 and have made numerous changes and repairs. The bilge pump (manual) works fine, the outboard is fine.... the last thing is the seacok that looks old and brittle. I have not touched it as I know nothing about them, this is my first boat. I have no toilet just the seacock under the cockpit. Any suggestions I have not had it in the water yet but I return in one week from an ASA 101/103 class and will put her in the water then.

 

[kloudie1]

Seacock for the sink drain? probably a good idea to go ahead and replace it with a Marlon one so ya don't have to worry about it.

 

[JamesG161]

yawl better contact Jabsco and Hunter and warn them of their poor design!

If you put the siphon break in the sea water intake line to the pump it will not pump water from the outside water

True!

If you look at their diagram, I posted, closely....

The hand pump pushes sea water over the top of high loop to the top of the bowl and "swishes".

Thus...

The siphon stops by vent or stopping the pump and locking it!

No need to respond on this anymore!

If you don't want a Jabsco twist lock design, don't do it. Mine works as shown.

Good flushes and no flooding wished for all....

Jim...

PS: passes more beer, the result is easier flushes.

 

[Joe]

But wait!!! You have to stop and ask yourself: "Why would the twist and lock feature only be offered on Jabsco's CHEAPEST marine toilet (in fact it's just about the cheapest of all currently made marine toilets)? And.... if it works so well.... why do they still recommend a vented loop on the discharge line.... which would make the twist 'n lock unnecessary any hoo.?"

I admit I have a new Jabsco twist n lock on my 38 year old Cat 27 and so far so good... it replaced the crappy old WC head mate... but the reason I bought it was because it was on sale for $129 at WM... I really was hoping to find a Raritan PHII on sale... but...you know...

Anyway... I would never trust the twist n lock feature as an anti siphon feature.... why???? because you can't insure that every guest and crew will use it properly... so what's the point?

 

[Peggie Hall HeadMistress]

But wait!!! You have to stop and ask yourself: "Why would the twist and lock feature only be offered on Jabsco's CHEAPEST marine toilet (in fact it's just about the cheapest of all currently made marine toilets)?

That's because it's Jabsco's only MANUAL toilet. Twist 'n' Lock wouldn't work on an electric toilet because there's nothing in one to twist OR lock.

And.... if it works so well.... why do they still recommend a vented loop on the discharge line.... which would make the twist 'n lock unnecessary any hoo.?"

One has nothing to do with the other. A vented loop will not stop backflow, it can only break a TRUE siphon that gets started back toward the toilet through an open thru-hull...something that the pressure of the hull against the water when the boat is underway can cause to happen in certain conditions. A vented loop in the discharge line is not needed if the toilet flushes only into a tank....however a LOOP can be a good idea to prevent tank contents running back to the bowl when a boat is heeled.

 

[Scott T-Bird]

Hmm ... this thread seems to have drifted a bit, but I'm glad for it. I don't think I have a vented loop for the intake, just the discharge. I am going to take a closer look.

My variable is that the top of the bowl is just a few inches above the water line. I've seen the bowl fill with an open joker valve. I've also seen the bowl overflow on a few occasions when heeled to stbd more than 20 degrees for extended periods with the valve open. I always just assumed that it would be good practice to simply close the intake seacock when sailing heeled over to that extent so that you are not relying upon the joker valve.

It does make a difference that the seacocks are all easily accessible on our boat. I close them all simply because I can easily. If they weren't easy to get to, I don't know that I would close them all the time.

 

[JamesG161]

My variable is that the top of the bowl is just a few inches above the water line. I've seen the bowl fill with an open joker valve. I've also seen the bowl overflow on a few occasions when heeled to stbd more than 20 degrees for extended periods with the valve open. I always just assumed that it would be good practice to simply close the intake seacock when sailing heeled over to that extent so that you are not relying upon the joker valve.

Well if you have a vented loop and the vent is just a air intake valve that could be plugged too.

Assuming your water intake thru hull is always below water line, then a siphon could be started by wave action too. The wave kinda acts like a pump.

If you have a manual pump type head, email me and I will tell you a trick to see if you have a working vented loop or not.

Scott T-Bird, are you sure about the Head/water level ? That sounds a bit close NOT to have a high point, vented loop.

Jim...

PS: Inside joke.... Scott worry about spiders plugging the loop vent.

 

[Scott T-Bird]

Nope, I'm pretty sure mine looks exactly like this.

http://www.chessie.com/boat/documents/Head-Mate.WC.pdf

There is no vented loop. Just a short run from pump to toilet. If I leave the through hull open and the joker valve open, I eventually have a bowl that is full to within about 2.5" from the rim. I'm figuring that is by design. When sailing and heeled more than 20 d she will slosh out. I was always glad that the lake water is pretty clean & freshwater. I'm thinking about additional safeguards at this point, being in brackish water. I can see where a vented loop may not be such a bad idea.

 

[JamesG161]

There is no vented loop. Just a short run from pump to toilet. If I leave the through hull open and the joker valve open, I eventually have a bowl that is full to within about 2.5" from the rim.

From the picture, no high point loop for sure ( and no spider worries ).

On a calm, not underway, day the bowl water level should equal the boat static water line.

OMG 2.5"

When I drink with a straw, I can easily pull about 5" water pressure.

Heeled or not, wave action can push more that 2.5" water pressure. I would open fresh water supply sea cock, only when in calm water use. Close after use.
Jim...

 

[Scott T-Bird]

I have not found any circumstance where wave action would really cause an over-flow. There seems to be too much friction in the system from the length and small diameter of the intake line, and the pump mechanisms. If I leave the seacock valve open and the lever up (joker valve open), the bowl never fills immediately. It takes a fair amount of sailing to fill the bowl, and only rarely will it slosh out when heeled for long runs at 20 d or more. There seems to be enough buffer to prevent wave action from causing a problem.

It really hasn't been an issue so far, but I think I will change it to a vented loop. Peggy seemed to respond that vented loops are required only when the bowl is below waterline and she also indicated that the bowls are typically delivered with that short run for the intake and it is necessary to change it out. I didn't realize that.

 

[JamesG161]

Scott T-Bird, I would check with the Manufacturer, since they do both above/below WL work. They should offer you the correct high point loop design and parts.

If you make the loop too high/tall, their pump won't push flush water over the loop top.

I forgot I looked up your lake before. Not much high seas to worry with.
Jim...

 

[Peggie Hall HeadMistress]

If you make the loop too high/tall, their pump won't push flush water over the loop top.

Any toilet--manual or electric--that's working anywhere close to factory spec can move bowl contents at least 4 vertical feet. According to the "performance" specs on page 1 of the instructions for pre-Twist 'n' lock manual toilets Jabsco manual toilet pre Twist 'n' Lock , "waste pump discharges up to 3 METERS (9 feet) above the base." There's no reason to think they'd make the pump on the Twist 'n' Lock version any weaker.

How high the loop needs be isn't a 'one size fits all boats' number that the manufacturer can supply because different boats heel to different degrees. The loop needs to be at least 6-8" above waterline AT ANY ANGLE of heel. On most sailboats, that will put it 2-3' above the bowl to keep it that height at maximum heel. But it can be higher or lower depending on how much the boat heels. Big wide "wallowing cow" cruising boats may only heel about 15 degrees in any conditions...sleek performance hulls can heel 30 degrees or more.

Wave action isn't the issue... Scott, your own bowl fills up when you're sailing with the seacock left open...no matter how slowly that happens, it should be enough to tell you to install the vented loop in the intake...'cuz many boats sink in their slips when the intake seacock is left open and the toilet is left in the "wet" mode, or the wet/dry cam assembly fails. I've seen high winds pushing water toward a boat with an open head seacock and no vented loop fill a bowl while it's sitting in the slip. Fortunately people were aboard to close it before the bowl overflowed. Had there been no one aboard, that boat would have sunk in a just a few hours.