Bilge Pump - Check valve?

[flapbreaker]

I was wondering if the bilge pump hose should have a check valve in it? I was 30 miles offshore fishing halibut this weekend and noticed water accumulating in the bilge area faster than I thought it should. The pump would need to cycle every couple minutes. Needless to say there was a few moments of panic. I tightened the plug but that didn't seem to slow the accumulation of water. Since that's the only below water line hole my thoughts quickly turned to the possibility of a hull failure. For some reason I decided to remove the bilge pump from it's base and was pleased, or rather relieved to see water dumping out of the pump with each wave that would slop up the side of the boat. While under power the bilge exit port would never be underwater but while at rest in sporty seas and a few guys standing in the back fishing that port can at times get submerged. I want to add a check valve but don't know if there's a certain kind for this task. Also would it be ok to put it inline near the pump instead of near the exit port? Ideas?

[tsturm]

[Sea Wolf]

Spencer-

tsturm's idea of a loop above the outlet is the best solution. Just keep it only high enough to stop the water from flowing in, otherwise the extra height will limit the pump's output.

You don't want a check valve in the system. It is a restriction and will limit the output volume of the bilge pump, which could be disasterous in an emergency.

Joe.

[thataway]

Also the check valves have a fairly high rate of failure in the marine environment. There are other types of bilge pumps--such as diaphragm pumps, which have valves, rather than the cheaper, high volume vane pumps that most boats come with.

The loop will do the job, but without a siphon breaker can back siphon if the water is high enough and the discharge hose fills with water.