Bilge Pump Size

[Cheers]

I am replacing my burnt out Rule 1100 gph bilge pump. What is the acceptable size (min and max) to use?
Is there an official rating system? eg; a boat of 35.5' size must have atleast 1100 gph.
Thanks.

 

[Don S/V ILLusion]

No single bilge pump system is large enough to keep up with a leak caused by hull damage. Bilge pumps are designed for small quantities of water and are not damage control pumps like the ones the USCG helicopters drop.

Having said that, it's easy enough to find out the flow rate of a specified hole diameter and size your pump(s) accordingly if that is what your intended goal is. If so, keep in mind the rating and the actual volume of water it can pump are mutually exclusive things.

Or you can abide by the other theory that you should have the largest pump you can physically fit in the available space (with a correspondingly large enough hose to not restrict it's flow).

 

[Franklin]

Cheers:

You should have two pumps.

First pump should be fairly small. The bigger the pump the bigger the hose and the bigger the hose, the more run-back you get when it stops. You can have a hose that holds as much water as it takes to flip the switch so it is a continual cycle...pump...drain...pump....drain. So you don't want too big of a primary pump. Plus, if you ever get a mild leak, you want the pump to be overpowered (See next pump)

Secondary pump should be connected to a switch a few inches above the primary pump switch. The switch should also be connected to a high water alarm. So when the primary pump is over run, the secondary pump will turn on and also an alarm will inform you that there may be trouble below (other possibility is the primary pump is not working). If you make the secondary pump as big as you can fit, then if you do get a leak below the waterline, it will help keep the water level down which will help you find the leak. That's very important because it's hard to find a leak when the leak is covered with water.

I have a rule 2000 (too big) for my primary pump and a rule 3700 for my secondary. Contray to belief, they do pump a lot of water and can handle 4 open thru-hulls wide open. Gotta make sure the engine is running when both are running for a long time or it will kill my batteries in a 8 hours if on a full charge. And yes, I've had a need for the rule 3700 before.

Rule 8000 takes a 3" hose
Rule 3700 takes a 2" hose
Rule 2000 takes a 1" hose
....

 

[Cheers]

Thanks for the helpful info. Much appreciated.

Thanks.

Cheers:

You should have two pumps.

First pump should be fairly small. The bigger the pump the bigger the hose and the bigger the hose, the more run-back you get when it stops. You can have a hose that holds as much water as it takes to flip the switch so it is a continual cycle...pump...drain...pump....drain. So you don't want too big of a primary pump. Plus, if you ever get a mild leak, you want the pump to be overpowered (See next pump)

Secondary pump should be connected to a switch a few inches above the primary pump switch. The switch should also be connected to a high water alarm. So when the primary pump is over run, the secondary pump will turn on and also an alarm will inform you that there may be trouble below (other possibility is the primary pump is not working). If you make the secondary pump as big as you can fit, then if you do get a leak below the waterline, it will help keep the water level down which will help you find the leak. That's very important because it's hard to find a leak when the leak is covered with water.

I have a rule 2000 (too big) for my primary pump and a rule 3700 for my secondary. Contray to belief, they do pump a lot of water and can handle 4 open thru-hulls wide open. Gotta make sure the engine is running when both are running for a long time or it will kill my batteries in a 8 hours if on a full charge. And yes, I've had a need for the rule 3700 before.

Rule 8000 takes a 3" hose
Rule 3700 takes a 2" hose
Rule 2000 takes a 1" hose
....