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Old 10-10-2019, 06:14   #1
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Engine Bilge Pump

On another forum that I look at there was a story and video of a boat that suffered a large leak in the engine room . I will not get into the details of the failure here as it will cloud the answers
What they did, I believe was disconnect the seawater intake and stick it in the bildge ,which was very clean I might add.

My question is has any one inserted a valve in their intake line that would allow for this to be done with a quick throw of a lever ? I have 3gm yanmars similar to the boat in question
I understand the concerns may be refuse plugging the line , air leak in normal operation and perhaps loss of prime in water pump.
My friend is captain on a 57 sport fisher and has a way to do this . In theory he has two 1250 hp bildge pumps!!

The boat in question sailed back overnight to port with the diesel on idle pumping out the bildge
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Old 10-10-2019, 06:23   #2
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Engine bildge pump

The amount of water your raw water pump pulls is quite small, very small.
Much better to have a back up bilge pump.
If you really must have an engine driven water pump, they are made that fit on the drive shaft and when there is no water, they pump air out bringing more cool air into the engine compartment, and they can move a huge amount of water. Nothing to engage, the pump runs whenever the shaft is turning.

I have never seen one myself, but I can’t find fault in it.
http://www.yachtwork.com/product-bilge
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Old 10-10-2019, 06:32   #3
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re: Engine Bilge Pump

https://www.groco.net/products/valve...ves/sbv-series
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Old 10-10-2019, 06:32   #4
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re: Engine Bilge Pump

You have seen how much water comes out your exhaust. Not much, right? I agree with 64, add more high volume bilge pumps. Just be certain to give each pump its own unique overboard discharge. To not do that is to risk a backflow back into the boat. You might also want to add a high water level alarm to give you a heads up as to when you do have a leak. All that is, is a float switch and a buzzer.

If you are concerned about your electrical system shutting down and your electric pumps not working, then install a Y-valve with an overboard discharge in your raw water inlet. Something is better than nothing. The downside to that is you have just added another way to flood your boat.

Be sure to have a hand pump/foot pump with a discharge tube long enough to reach overboard if all else fails.
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Old 10-10-2019, 09:48   #5
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re: Engine Bilge Pump

Personally I am not worried,I have pumps in each engine room , I was just thinking about a little redundancy. It seems a simple way to get a bit extra with the advantage of running through the night etc .
Does anyone think there is a down side other than those I brought up .
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Old 10-10-2019, 09:52   #6
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re: Engine Bilge Pump

Quote:
Originally Posted by Gary S View Post
Thanks Gary cool item
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Old 10-10-2019, 10:05   #7
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re: Engine Bilge Pump

On large power boats it’s a great idea. I rigged the intake on my 210 hp Cummins so that by turning two valves it would pump the bilge. It had an 1-1/4” pump. Sailboats often have 3/4” pumps on their engines. Might not be worth the effort but it costs almost nothing and you don’t have to install a thru-hull for the discharge.

A belt driven pump is a great idea.

You’ll hear people argue that you’ll damage your engine using it to pump the bilge. If your boat sinks, the engine is pretty well damaged anyway. Even if your bilge has trash in it, your strainer should catch it. Keep your bilge reasonably clean and it won’t be a problem.
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Old 10-10-2019, 10:59   #8
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re: Engine Bilge Pump

Stick a bucket under your exhaust for a minute. At idle my 3GM30 was about 1.5 gallons. I think we can assume linear relationship because it is a positive displacement pump, so under 7 g/min at wot. 420 g/hr. Compare to bilge pumps made for the purpose.
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Old 10-10-2019, 11:14   #9
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re: Engine Bilge Pump

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Originally Posted by cal40john View Post
Stick a bucket under your exhaust for a minute. At idle my 3GM30 was about 1.5 gallons. I think we can assume linear relationship because it is a positive displacement pump, so under 7 g/min at wot. 420 g/hr. Compare to bilge pumps made for the purpose.
That is interesting, It would be a substantial % increase to most of the pumps used for this
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Old 10-10-2019, 11:15   #10
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re: Engine Bilge Pump

The engine turning an alternator is often the only way to power the electrical bilge pumps for an extended period of time on smaller boats. To lose that powering ability because you sucked something into the water pump would be catastrophic too. At least fit a strainer to the blige intake.

We have this set-up on our boat, but the Jabsco three-way valve leaked air and caused all kinds of problems until I located the culprit.

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Old 10-10-2019, 11:25   #11
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re: Engine Bilge Pump

They dont pump much.
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Old 10-10-2019, 12:05   #12
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re: Engine Bilge Pump

Been there did that -- believe me, you want extra bilge pumps; however, the engine pump will work, albeit not being the preferred method...

See: https://www.sailblogs.com/member/awing/69884
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Old 10-10-2019, 12:15   #13
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re: Engine Bilge Pump

I worked on a fishing boat that had a high volume pump hooked up to a GM 6-53 via a electrical clutch, we could empty the ice melt very quickly. So maybe not the raw water pump, but a belt driven pump is the answer.
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Old 10-10-2019, 13:12   #14
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re: Engine Bilge Pump

Hydraulic dewatering pump would be nice and hope you'll never need it.

We don't have one but do have 3 x 3500gph bilge pumps set at different levels with floats and the last one alarmed.
And 2 x 3700gph 240v submersibles brought on line at the flick of a switch
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Old 10-10-2019, 13:24   #15
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re: Engine Bilge Pump

how about a impeller style pump on the drive shaft. I have seen pumps used on military Duck boats that have an impeller inside a closely fitted housing around the prop shaft. They draw water in around both sides of the shaft to a vane style pump and discharge overboard above the water line. No friction or seals to worry about and they only pump when submerged. I guess that they probably move a little air when not submerged. I saw a demo and i think that these were moving many thousands of gallons an hour
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