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Channel Islander's picture
Channel Islander
Last seen: 9 hours 7 min ago
Joined: 10/8/11
Posts: 378
Bilge pump to sink drain?

Hi all,

I think I read somewhere of an owner who routed his 'nuisance' bilge pump discharge to his sink drain. Given that the sink is almost on the centerline, it seems that I could use a vented loop and safely discharge the bilge water down the drain hose with a tee. I can't find the article I think I read, so I'm wondering if anyone has done that on their C36?

I plan to follow Tom Soko's system for two bilge pumps, a serious one mounted a little higher and a small one for the nuisance water. Want to minimize backflow and the sink drain is the closest thing.

Any thoughts?

Thanks

nick

Nick Tonkin
*Former* Website Administrator, C36/375IA
*Former* owner, C36 tr/fk #255, Santa Barbara, CA

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Nick Tonkin
*Former* Website Administrator, C36/375IA
*Former* owner, C36 tr/fk #255, Santa Barbara, CA
TomSoko's picture
TomSoko
Last seen: 3 months 1 week ago
Joined: 2/15/07
Posts: 978

Nick,
If you are looking for minimal backflow, then you can put a vented loop up near the sink, and the backflow will only be the amount of water in the hose between the pump and the vented loop - a tiny amount. Here are the pix of my project, including the vented loop. I suppose you could tie into the sink drain, but it is always better to have each bilge pump with its own dedicated discharge at the transom, according to what I've read.
[URL]http://www.c36ia.com/node/944[/URL]
Hope this helps.

--

Tom Sokoloski
C36/375IA Past Commodore
Noank, CT

stu jackson c34's picture
stu jackson c34
Last seen: 1 week 5 days ago
Joined: 12/3/08
Posts: 1269

And tying into the sink drain would require you to leave that thru hull open when you're not there. We close all of our thru hulls when we leave the boat. Always.

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

Steve Frost's picture
Steve Frost
Last seen: 5 years 8 months ago
Joined: 12/14/07
Posts: 788

Another issue with using the sink drain is a safety margin issue. The Sink drain is way too low. In a significant flooding situation its outlet would be well below the water line greatly reducing the efficiency of the pump. It would also require a very good check valve to prevent back flow in the event of bilge pump failure. The issue is the seacock for the sink is below the water line, the sink drain and refer are above, though the refer can get sea water in it if its check valve gets clogged and the boat is heavily heeled to port.

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Cepheus dream
C36 MK I # 825
MK I Tech Editor No Mas

Channel Islander's picture
Channel Islander
Last seen: 9 hours 7 min ago
Joined: 10/8/11
Posts: 378

Tom, thanks, I've studied your guide closely. It was the inspiration for the two-pump plan to begin with.

Stu, I live on my boat, so it's just not practical to shut all the thru-hulls every time I leave. I would be opening and closing them multiple times a day. I guess you're right that I would want to close everything up if I was away for a spell. Although the current life plan has me never again crossing the railroad tracks on the other side of the harbor -- all travel to be seaward aboard True Friend -- maybe I'll have to go to the transom after all.

--
Nick Tonkin
*Former* Website Administrator, C36/375IA
*Former* owner, C36 tr/fk #255, Santa Barbara, CA
Channel Islander's picture
Channel Islander
Last seen: 9 hours 7 min ago
Joined: 10/8/11
Posts: 378

Tom, a follow-up question if I may . . .

Did you have to cut a hole in the bulkhead outboard of the bilge to admit the discharge hose for the new pump in the middle compartment? Both my existing bilge hoses have holes cut to fit, both leading into the aftmost compartment.

Also, if you reduced the diameter of the discharge hose from the aft compartment (because you downsized the pump there), did you fill in the hole around the hole to seal the bilge from the outboard compartment? The existing hoses almost look glassed in so I am considering routing the 3/4" hose through the existing 1 1/4" corrugated. Cut that outboard of the bulkhead, couple to a new section and rout into the middle compartment through a new hole. Does that sound reasonable?

Thx,
nick

--
Nick Tonkin
*Former* Website Administrator, C36/375IA
*Former* owner, C36 tr/fk #255, Santa Barbara, CA
Channel Islander's picture
Channel Islander
Last seen: 9 hours 7 min ago
Joined: 10/8/11
Posts: 378

Wouldn't the vented loop be under the waterline if the sink drain was?

And couldn't the standard bilge pump-direct-to-transom setup flood the boat if the stern was under water, as in a heavy following sea?

I must be missing something, can anyone help me understand?

[QUOTE=Steve Frost;12246]Another issue with using the sink drain is a safety margin issue. The Sink drain is way to low, in a significant flooding situation its outlet would be well below the water line greatly reducing the efficiency of the pump. It would also require a very good check valve to prevent back flow in the event of bilge pump failure. The issue is the seacock for the sink is below the water line, the sink drain and refer are above, though the refer can get sea water in it if its check valve gets clogged and the boat is heavily heeled to port.[/QUOTE]

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Nick Tonkin
*Former* Website Administrator, C36/375IA
*Former* owner, C36 tr/fk #255, Santa Barbara, CA
TomSoko's picture
TomSoko
Last seen: 3 months 1 week ago
Joined: 2/15/07
Posts: 978

Nick,
I THINK that Julandra came from the factory with the large hose for the manual bilge pump into the middle compartment, and the large hose for the electric pump into the aft compartment. I simply switched them when adding a second bilge pump. I did not have to drill a new hole when adding the second pump. The small hose goes STARBOARD under the cabin sole, aft over the stringer, then inboard and up to the galley sink area.

As near as I can figure, the boat would have to be 18-24" below her lines before the vented loop I installed near the top of the sink would be under water. If there is that much water in the boat, the nuisance pump would be one of the last things I would be thinking about!

As you may have learned by now, CY makes many changes on the fly, and not necessarily at model year or Mark changes. Your boat may be different.

The OEM bilge pump hose goes outboard to port, aft along the hull, then up to the TOP of the transom, then down to the thru-hull. Even if the stern was half-submerged, water should not flow into the hull thru the bilge pump hose.

I have read in many places that check valves should NOT be used in bilge pump hoses. Hope this helps.

--

Tom Sokoloski
C36/375IA Past Commodore
Noank, CT

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