Galley sink waste outlet

[jon]

Thanks, yes good point, however 180mm (at v best) does not seem much!
As I have not installed the manual bilge pump yet, incorporating a diverter valve for the sink is a relatively easy job at this stage.

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[MainlySteam]

Fine Jon.

We have double sinks, bottoms I guess about 200 mm above the waterline and the outboard one would be further out than yours and I have never known it to back flood. That is in a boat with quite alot of form stability so might float the basins higher above the waterline when heeled than a narrower traditional craft.

In any event, in the case of any doubt of them being free from flooding, Mirelle's suggestion which, as always /forums/images/icons/smile.gif, is founded on sound experience is sure to work.

John

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[Mirelle]

Subject to the views of the Headmistress...

I agree with you that the nonreturn valve above the outlet is probably unnecessary; I incuded it simply as a belt and braces measure against siphoning back at high angles of heel - since the diapraghm pump already has a pair in it and one can shut the seacock the extra valve is overkill.

Assuming that you pump enough to get air past the U bend I see no point in a siphon breaker, but I would defer to Peggie Hall on that.

I agree the Jabsco diverter is better than the Whale; had I known of it at the time I would have used it.

The outlet need not be at any great height in the topsides - I would suggest about the same as the engine exhaust - the safety point is that it should be above water with the boat at anchor or moored and unattended.

With this sstyem one can use the sink at any angle of heel; the plug does not pop out, annoyingly, after being put in, with changes in the boat's motion, (indeed, the pug is unnecessary) and one can dispose of quite sizeable food residues (porridge, rice and pasta saucepans come to mind) down the sink without worrying about blocking something.

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[HeadMistress]

Re: Subject to the views of the Headmistress...

I didn't take into account the idea of pumping water through a drain, but allowing gravity and the pressure from water flow to empty the sink.

A vented loop/siphon break only interferes in a line in which liquids are pulled...air is pulled into the line, preventing it from priming (priming is how a siphon is started). It has no effect on anything pushed through a hose. So in a drain in which water is only being pushed, the pump should be enough, provided the pump is well above the waterline and the seacock is kept closed while the boat is underway except when the sink is actually in use. If someone is at the sink, it's a simple matter to close the seacock should a geyser develop...a problem otoh, if no one is aware of it till the sink overflows.

Re diverter valves. Have you ever taken a Jabsco y-valve apart? Instead of a full "barrel" that rotates to move the openings to one outlet or the other, there's only small--and very flimsy--barrier that moves to block one side or the other. Any mineral buildup or anything else that can create any resistance is likely to break it. I have to admit that I do like the hose barbs that rotate to any position, though...it's just a shame that the innards aren't more substantial/durable.

I'm not all that taken with Henderson y-valves either...unlike Whales, on which the tailpieces are integrally molded with the body, the tailpieces on Hendersons are held on with bolts and sealed with rubber gaskets. Just last month, while doing some consulting work for a boat dealer, I found 3 in a row on 3 separate boats that leak at those connections.

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