Bilge Pump Hose Length

[kcmarcet]

After reading about how wimpy bilge pumps are and looking at the specs for my pump I am a little concerned that my hose run may be too long. First my pump is a Rule 360 gph but the specs for the pump seem to put the output somewhere between 0 and 100 gph with a 12 foot hose run with a rise of about 12 inches. I think I might have to test the pump to check it's flow, I just am not sure how I should test it. Should I intentionally put some water in the hull to check it's flow? I am more concerned about it's pumping ability while the boat is anchored while I am not onboard.

[S/V Illusion]

It has very little to do with the hose length (as long as you use smooth hose) and everything to do with the head against which the pump has to push. At no head, your pump will push 360 gph theoretically. Measure the rise between the pump and discharge and any additional head from the backflow loop and you can easily read the advertized pump rate. If you have a check valve, it will be less still.
Fill up the bulge with water and test it. That should be part of your normal maintenance routine anyway.

[GordMay]

Originally Posted by S/V Illusion

It has very little to do with the hose length (as long as you use smooth hose) and everything to do with the head against which the pump has to push...

FRICTION LOSS IN WATER HOSE

At 5 GPM water flow (360 GPH) a clean 1-1/4" I.D. smooth hose will have
about 0.765 Feet of Head Friction Loss (0.32 PSI Pressure Drop), per 100 foot of hose.
The same 5 GPM discharge through a 1" I.D. hose will have about 2.194 Feet of Head Friction Loss (0.95 PSI) per 100'.

See Dave Gerr's
Boat Mechanical Systems Handbook
➥ Boat Mechanical Systems Handbook ... - Google Books

➥ http://www.ppt-hose-tech.com/Downloa...ion%20Loss.pdf