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Old 06-15-2015, 03:14 PM   #1
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Bigfish's Avatar
City: Salem, Oregon
Country: USA
Vessel Name: My Lady
Vessel Model: Formosa 42 Double Cabin
Join Date: Jan 2013
Posts: 81
Electric Pump to replace Westerbeke Mechanical Raw Water Pump?

Anyone tried this? I'm now working at West Marine and my employee discount is pretty good. I just pulled my raw water pump off my 7.7 kw Westerbeke because it was leaking water. I did this two years ago when I bought the boat and the rebuild kit is almost $200. A customer at WM with the same generator and pump said his seal goes every two years. It's a major pain to get this thing on and off and another customer said he'd replaced his with a raw water air conditioning AC pump that turns on when he starts the generator.

I can get a 300gph March pump for about the same price as the rebuild kit but I'm not sure about the flow rate on the original pump at the 1800 rpms the generator runs at.

Any thoughts on this? I'd like to match the flow rate as closely as possible. Also could use some ideas on how to wire the AC pump to start when the generator does.

Thanks folks. I'm out on a mooring ball in Boot Key Harbor waiting on the two new exhaust elbows for my Lehmans to show up too. Slowly but surely..

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Old 06-15-2015, 03:17 PM   #2
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City: South FL
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Vessel Name: Oliver
Vessel Model: Nordhavn 47 Hull# 12
Join Date: Apr 2013
Posts: 3,601
We had a 3.5 Phasor genny and went with the March pump setup 500GPH I think it was. Worked like a charm. Wired it to the breaker on the generator so there was no way I could hydro lock the engine.

Thanks, Oliver
M/V Oliver
Nordhavn 47 Hull #12
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Old 06-15-2015, 04:33 PM   #3
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City: Sarasota/Ft. Lauderdale
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It will work. Just remember that those March pumps are not self priming.
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Old 06-15-2015, 04:56 PM   #4
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City: Friday Harbor, WA
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Vessel Name: Hobo
Vessel Model: Krogen 42-120
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Here's a link to someone who made the change on an 8 Kw Northern Lights generator. He addressed the priming issue.

Pages 12-15

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Old 06-16-2015, 05:50 AM   #5
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Join Date: Oct 2007
Posts: 14,908
Some of the March pumps use a magnetic drive , so there is no shaft seal to die.

Dont know if they come in large enough sizes.

But I have seen 4-107 and similar sail boat engines cooled with 12v bait well pumps with total success.
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