Installing automatic bilge pump in series with diaphram bilge pump... - SailNet Community

 
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post #1 of 7 Old 10-26-2009 Thread Starter
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Installing automatic bilge pump in series with diaphram bilge pump...

I recently purchased an automatic rule bilge pump. My sailboat, a Yamaha 30C is equipped with a manual diaphragm pump. Is it ok to connect the automatic bilge pump outlet directly to the input of the manual diaphragm pump?

The two pumps will then be in series instead of having separate inlets and outlets. The diaphragm pump should act like a check valve I believe. Has anyone else done this? Any issues? Any input will be greatly appreciated. Thank you.

SD
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post #2 of 7 Old 10-26-2009
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You'd be seriously degrading the performance of the electrical pump (if it worked at all), and you'll really have no redundancy in your systems. A clog of any kind anywhere would incapacitate both pumps.

You'll be far better off with two separate systems, including discharges.

Ron

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You do realize that doing this will probably reduce the output of the Rule bilge pump by over 50% of its rated capacity... Generally, centrifugal pumps, like the Rule, should have as short a run with smooth walled hose and no check valves as possible. The diaphragm pump will act as a set of check valves and cut the output drastically.

You're really better off putting each pump on its own output..... I'd also point out that if you're taking on water, having the two pumps in series means that you're limited to using one or the other... not both... and that might cost you your boat—pennywise and really pound foolish.

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post #4 of 7 Old 10-27-2009
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Run it separately

I went through this a while back. And there was a discussion on SailNet. (But I can't seem to post a linkback to the Gear-Maintenance Forum thread 44434 from 6/25/2008 without the automatic shopping link interrupting!).


End result: Rather than putting another hole in the hull, I dumped the output from the second (electric) bilge pump into the cockpit, from whence it drained out the (sizeable) scuppers. Side benefit: when your feet get unexpectedly wet, you've just been informed you have a serious problem.

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post #5 of 7 Old 11-07-2009 Thread Starter
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Thanks everyone for the advice. I am going to routing the discharge to the cockpit sounds easy and a good idea.
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post #6 of 7 Old 11-07-2009
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In our boat, either Sabre or the dealer separately routed the outputs from the rule pump and the manual aft. They then joined them in a "T" about 12" from the overboard discharge. Works beautifully. Note that I discarded the check valve that someone put on the rule pump and installed a vented loop to minimize backflow.

To be honest, if I'm ever in a situation where I need both pumps to keep the boat afloat, I'm breaking out the bucket and switching the engine intake to bilge intake!

Sabre 38 "Victoria"
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First, a good manual bilge pump would work better, and let you pump longer and faster than a bucket would... and second, using the engine to empty the bilge is IMHO a relatively stupid idea, as most sailboat diesels pump relatively little water and running the risk of compromising the engine when its power may be needed most is not very smart. Most bilges have a fair amount of debris and such that are likely to clog the engine cooling passages.

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To be honest, if I'm ever in a situation where I need both pumps to keep the boat afloat, I'm breaking out the bucket and switching the engine intake to bilge intake!

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