Bilging Every 3 Minutes

[Plymouth Sailor]

Dear Sailors,

How common is it for the bilge pump to go off every 3 minutes? I understand that there should be no regular bilging as this represents a leak of sorts. I’m still endeavoring to find the leak but I’ve seen other boats regularly bilge. I have no less than 7 holes/thru-hulls below the waterline. Any wisdom, suggestions welcomed!

 

[odaydokay]

Is this an inboard engine? If yes, checking the stuffing box would be a place to start.

 

[Davidasailor26]

Every 3 minutes would definitely concern me. Routine causes of nuisance bilge water include keel stepped masts and stuffing box drips. Neither of those should cause enough water to trigger the pump every 3 minutes. One other thing to check is whether water is back flowing from the discharge line into the bilge, filling it back up right after the pump out. That could make it seem like more incoming water than there is.

 

[Plymouth Sailor]

Every 3 minutes would definitely concern me. Routine causes of nuisance bilge water include keel stepped masts and stuffing box drips. Neither of those should cause enough water to trigger the pump every 3 minutes. One other thing to check is whether water is back flowing from the discharge line into the bilge, filling it back up right after the pump out. That could make it seem like more incoming water than there is.

Thank you!

 

[Hollyberry]

How long does it pump each time? If very brief (and you don't see much water exiting the discharge) David could be on the money.. your foot valve might leak back.. Otherwise a leak that caused the bilge pump to run every 3 minutes should be easy to find!!

 

[PaulK]

We found our bilge pump recycling a lot too, but not enough leaks to account for it. Until... we determined that the bilge pump hose was really long, and had a check-valve in it to keep water that had been pumped from returning to the pump. And the check-valve was leaking. Essentially the pump would fill the hose and then the water would leak back into the boat, set off the pump and get pumped until it filled the hose again. Quite annoying.

 

[dlochner]

It is most probably cycling because of water back flowing through the hose. It should be easy to check. Watch the pump, do you see water draining back through the pump?

The typical pump has rigid vanes which work well when they are pushing water, not so well pushing air. Once the pump has emptied the bilge it can not pump water the rest of the way up and out the hose. The water drains back into the bilge and the cycle starts again.

Some Rule pumps have check valve in the pump outlet that stops the back flow.

 

[Stephan]

Many Automatic bilge pumps today have an electronic check system that is engineered to cycle the pump to see if there is sufficient pressure (water) to pump or run the motor. This is quite normal. It will turn on, see if it detects any water to "evacuate" and if it does it will go into pump mode.

Rule calls this their "RuleMate Intelligence" system.
This technology also works to detect debris in the strainer basket that can lead to a pump failure because it runs, but will not evacuate water due to the debris.

Stephan

 

[capta]

Many Automatic bilge pumps today have an electronic check system that is engineered to cycle the pump to see if there is sufficient pressure (water) to pump or run the motor. This is quite normal. It will turn on, see if it detects any water to "evacuate" and if it does it will go into pump mode.

Rule calls this their "RuleMate Intelligence" system.
This technology also works to detect debris in the strainer basket that can lead to a pump failure because it runs, but will not evacuate water due to the debris.

Stephan

Yep, Stephan, you are quite correct. Three minutes is about the normal cycle if memory serves. I guess it would help to know which pump we are talking about.

 

[capta]

We found our bilge pump recycling a lot too, but not enough leaks to account for it. Until... we determined that the bilge pump hose was really long, and had a check-valve in it to keep water that had been pumped from returning to the pump. And the check-valve was leaking. Essentially the pump would fill the hose and then the water would leak back into the boat, set off the pump and get pumped until it filled the hose again. Quite annoying.

If you are using a centrifugal pump (Rule style) check valves are a real no no. You will need to take it out of the line and add a vented loop in the system that goes well above the waterline (to the deck is best) to prevent the water from coming back through the pump if the exhaust fitting gets below the water. This will mean you will always have a bit of water that runs back from the vented loop, but it is reliable and safe.

 

[JamesG161]

check valves are a real no no.

Check valves plug up and need continuous maintenance. Not a safe thing for your boat.

A cycling bilge pump suggests its volume rate is undersized or your discharge line is too big.
Jim...

 

[LloydB]

How many gallons every three minutes? Somewhat important I think because you need to find out whether you have a slow leak or a slow pump. I can imagine a diaphragm pump with a pinhole in it taking that long to bring a pint of water to shut off pressure or a bad anti siphon valve. Otherwise for example if your auto pump switch turns on every time it gets a new one gallon of water then you had best find out where that 20 gph leak would be, just in case the pump stops working. A shop vac is your friend.

 

[Ken13559]

When at dock my bilge pump comes on regularly due to condensate from the running aircon.