Lav sink flooding.

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Steve Frost
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Lav sink flooding.

I would like to know if anyone has come up with a solution to the problem of the lav sink flooding on starboard tack. I took a group out for a Bay Tour on Saturday, coming across the bay from Suasilito to San Francisco we were hard on the rail on a starboard tack for about ten to fifteen minutes. I went check on the head as I had failed to shut off the through hull for the sink. I found the sink full and about eight inches of standing water on the wall behind the sink and the floor had about six inches of standing water. Using the shower pan sump pump is futile as it just pumps to the sink causing the level to go higher and generating a lovely water fall effect over the counter. I shut off the through hull, flattened the boat out and then used the sump pump to drain the head compartment.

One thought I have had was to have a spring loaded sink stopper like the type used on aircraft, this would seal the sink closed until you pushed the lever down to drain the sink. This may be a bit more inconvenient when using the sink but, better than sinking the boat on a long starboard tack because you forgot to close the seacock.

Cepheus dream
C36 MK I # 825
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dwarburton
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One answer might be a check valve. The ideal type would be the kind that uses a ping-pong ball like float to seal when the water is flowing up instead of down, since any kind of spring loaded check valve may have too much cracking pressure to allow the sink to drain. Plus, the check valve has to have enough flow area to pevent clogs.

I will look on the Mcmaster Carr website to see what is available.

I would also be inclined to experiment with some PVC fittings and a soft rubber ball like a handball or racketball.

My crew does not let me heel far enough have this problem :)
Dave

Dave
Ballena 1995 Mk II #1445

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Steve Frost
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Dave, I considered this but, water is water the ball will float regardless if the water is coming from the inside or outside the boat. I understand the spring and cracking pressure thought but, if you slowly heal over you may never have enough flow to overcome the spring pressure.

My congrats on your finding McMaster Carr if it is not in their catalog it is probably not made yet. It is Rube Goldberg's Bible. They do not have much in the way of marine products but, are a great source of materials and non marine items.

Cepheus dream
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dwarburton
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Steve,
I am an engineer by trade, and I have made good use of McMaster Carr over the years. I have ordered items from their west coast warehouse at 8pm EST, for 10 am delivery the next day.

Most of their marine hardware is disguised as "corrosive environment” It is a great place to buy hard to find SS fasteners (Like M5-20mm) etc.

The ball check valve will work if it is located above the waterline. When the sink drains, the column of water below the ball, but above the waterline will drain down, creating a continuous suction on the ball even if it is floating in the float chamber.

When the boat is heeled, and the check valve is below the waterline, the column of water below the valve is now pushing up against the floating ball, holding it against the valve seat.

The sink won't drain in this position, but the water will not backfflow either.

A spring loaded check valve requires a slight cracking force. Typically the short column of water above the valve will not have enough weight to compress the spring. Consequently the sink will not drain.

The interesting thing about this project is that you can build a few yourself in the basement and experiment until you find something that works.

Then you can take pictures and show the rest of us!

Dave

Dave
Ballena 1995 Mk II #1445

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Steve Frost
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Dave, I have two issues. One I understand the check valve would be moved above the water line, if I have the rail in the water this could be quite high and how do get the sink to drain when the boat is level. The water can not run up hill from the sink to the check valve in this hemisphere.

The second problem is, I do not have a basement.

I was thinking of the keep it simple system. Just a standard bathroom sink drain valve spring loaded that you need to press down to open.
(page 1970 of the McM.C cataloge 114) This does not rely on a float valve that can get gumbed up with schmutz or my no close due to slow inflow.
It also would help promote water conservation, the ladies would not just keep the water running when using the lav.

Cepheus dream
C36 MK I # 825
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dwarburton
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Steve,
The spring loaded drain will certainly work. it is simple and easy to clean too.

Just a note on the check valve for others considering the project. It needs to be above the waterline when the boat is level, allowing the sink to drain. When the boat is heeled, it must be below the waterline to allow it to seal.

Up in New England, not only do we have basements, but many of them have bilge pumps just like boats, since from March through May, the basement is below the waterline. At least when the bilge pump fails, the house doesn't sink, although all the boat stuff I have stored down there for the winter gets soaked, which is ironic.

Dave
Ballena 1995 Mk II #1445

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bfissel
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Last year I installed a whale check valve (same check valve in my discharge line from the frig) just below the sink drain above the waterline. It keeps the sink from filling on starboard tack. At times the drain needs a small push from a small plunger to drain if any foreign material is in the sink.

Bill
2000 MKII
#1896 Sweet Caroline
Chesapeake Bay

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Steve Frost
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Bill, thanks for the input, glad to hear that this works. I thought it may be to easily contaminated and not seal but, I have been wrong before.
This is most likely what Dave was thinking about and I may have misconstrued his thoughts. I some how envisioned that he was suggesting a check valve mounted above the sink in his plan.

Having the check valve right at the bottom of the sink would not effect the performance of the sink as it will not drain when the sink in below the water line anyhow.

Cepheus dream
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stu jackson c34
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Far be it from me to thwart your plans for an upgrade and improvement to your boat, Steve. We have a head sink, too. I almost never open the thru hull for the sink drain. We use the head, of course, but use the galley sink for hand washing. Of course, our head is closer to the galley than yours. Just tryin' to get you more sailing time! :D

Stu Jackson, C34IA Secretary, C34 #224, 1986, SR/FK, M25 engine, Rocna 10 (22#)

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