engine powered bilge pumps

[Brian Degulis]

im pretty sure swimming pool pumps need to be primed / bled and also be below water line making them useless to dewater a boat.

Lots of commercial boats have centrifugal pumps (pool pumps) if they have a reservoir they may self prime but you can't depend on it. So they mount the pump below the waterline and pipe it to a thru hull and a bilge suction with valves. So the pump is started and primed up on the thru hull then switched over to the bilge suction. With this set up the pump can be routinely tested and you can keep it primed using the thru hull if the pump is faster than the leak. It's a good emergency pump cause they move a lot of water.

Brian

 

[krush]

A pool pump does NOT need to be below the water level. They will self-prime within reasonable limits and pump like a banshee, plus have a strainer in the intake already.

They'll also massively "outpump" a bilge pump but are NOT submersible.

It depends on the setup. Unless you install some type of check valve, most will lose prime if mounted above the pumping level and air is exposed to the intake. Additionally, centrifugal pumps usually do not do as well "sucking" as positive displacement pumps.

Throw in the fact that centrifugal pumps can have a major reduction in flow rate as head increases. Most pool pumps are high volume/low pressure. I'd go with a fire pump style instead.

And last but not least, there is only so much water you can pump with such a limited amount of power (110v). Those engine mounted pumps probably take 10-20hp or more.

 

[drburke]

Actually, I bought a Harbor Freight stainless 110V pump (1HP) to keep around; they are only $59 bucks. I do worry that relying on the cheapest China product for such a task ain't smart on my part, though.

http://search.harborfreight.com/cpisearch/web/search.do?keyword=dirty+water+pump&Submit=Go

DAN