now I,m worried.

derekh

derekh

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seeing jims post on the wet p65 got me thinking. how long should brass loo intake fittings last before they become liable to failure. I have A single through hull intake and a seperate outlet I would never dream of turning them off, up untill now that is.
My old girl is almost 20 years of age and it is a sunseeker (next to sink according to earlier post). umm check insurance, but is it advisable to replace fittings after a while.

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The fitting itself (which I suspect is actually bronze, not brass) should last forever. The dangers when seacocks are left open are:

1. Hose clamps that fail resulting in a parted connected below the waterline.

To prevent such an occurance from sinking your boat, inspect all below waterline connections regularly and maintain as necessary. Check the thru-hull itself for signs that it may be leaking and require rebedding. Keep the seacock well lubricated and in good repair.

2. Reliance on the wet/dry valve in a toilet that's at or below the waterline to keep water outside the boat from seeking its own level inside the boat via the toilet bowl. Wet/dry valves fail...people fail to leave 'em in the "dry" mode even more often.

The safest solution is, of course, close the seacock when you leave the boat. Strict adherence to safety standards actually require that it be kept closed at all times except when the toilet is actually in use...but these days, boat builders are putting thru-hull in places that are so inaccessible as to make that impractical, if not downright impossible. So as an added fail-safe to protect the vessel while you're asleep at night, or away only for a few hours, a vented loop that's at least 8-12" above the boat's waterline should be installed in the head intake and in any other line--toilet or tank overboard discharge--that's below the waterline.

The loop serves two funtions: it provides an air break that prevents a siphon, and also creates a "hill" in the line that's higher than water outside the boat can climb over to flood the bowl.

If the boat has a manual toilet, the loop must be installed between the pump and the bowl (replace the short piece of hose that goes to the back of the bowl from the top of the pump with the loop and enough additional hose)...if it's installed between the thru-hull and the pump it will interfere with the pump's ability to prime.

If the toilet is electric (unless the intake pump is separate and remote from the toilet), there is no hose between the pump and the bowl...so it has to go between the thru-hull and the pump...which requires that an electric solenoid siphon break be installed and wired to operate when the button to flush the toilet is pushed.

The loop, coupled with regular inspections of all below-waterline connections, should allow you to sleep at night without worry that your boat will sink if you forgot to close a seacock.

<hr width=100% size=1>Peggie Hall
Specializing in marine sanitation since 1987
 
Thanks for the kind words!

One more thing I should have included: ALL sanitation system hose connections, and all other below waterline connections, should be double-clamped...two clamps--the screws on opposing sides of the hose. Not only does this help to prevent a parted hose connection, but it's also necessary to prevent leaks.

I'm glad to help solve problems--better yet, help you learn how to prevent them. However, I'm not altogether familiar with products and equipment made in the UK and Europe that aren't also distributed in the US, so you may have to help me out with information or direct me to a mfr's site before I can help you.

And you may have to help me learn a second language, too: English! I thought we spoke it too...but I've read entire posts here without a single clue what the person is talking about! :)

<hr width=100% size=1>Peggie Hall
Specializing in marine sanitation since 1987
 
<<<If the boat has a manual toilet, the loop must be installed between the pump and the bowl >>>

Not necessarily. If one uses a siphon breaker with a rubber duck bill valve or similar in it (such as the Forespar ones) it is possible to take the little valve out and replace it with a small piece of small celled open cell porous foam rubber (cut off that such as used for sealing access panels, etc). It will provide sufficient resistance to reverse air flow to enable the hand pump to prime and pump but allow enough air through to break the siphon when pumping stops (after installing you should check that air does flow back through it)

I was a bit sceptical of this when I first saw it done by the builder of my own boat, and kept a close eye on it for quite a while. However, it has never been a problem and the original piece of foam is still in there after 7 years. It doesn't seem to salt up.

The advantage of having the loop on the suction side of the pump halves the amount of pipework in the open between the pump and wherever one hides the siphon breaker loop so is a matter of tidiness in the toilet compartment only.

John

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Very interesting

And an idea I've never heard of before. Next time I'm in a chandlery, I'll make a point of investigating various vented loops to find out which ones have air valves that would allow this to work.

'Cuz not all will. Most vented loops have only nipple on the top into which an air valve is threaded. Because they're shipped and sold separately, many chandleries don't even stock the air valves...and most boat owners don't even know the valve exists. B ecause it's missing, the loop squirts when the toilet is flushed...so they clamp a hose onto the nipple that's either tied into another hose or goes to a tiny vent thru-hull (which, because it's so tiny, promptly becomes clogged by sea water minerals (or, in a discharge hose, waste), which makes the loop useless as a siphon break...but at least it still provides the arch in the line that's above the waterline.

Thanks for a VERY interesting idea!



<hr width=100% size=1>Peggie Hall
Specializing in marine sanitation since 1987
 
Re: Very interesting

No trouble Peggy.

I know it works with the Forespar ones. I think one of the reasons why the foam does not get gummed up with salt etc is that because it is on the suction side of the pump air is always trying to get into the siphon loop through it (in little amounts). Whereas in the normal application water is trying to get out, except of course when the loop drains down after flow ceases.

Pretty obviously, one needs to be sure that the foam is indeed permeable.

Regards

John

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