Bilge Pump Blues

[Mark Wey]

I  searched the board, could not find this one. My bilge pump is driving me nuts. Not having had the boat very long,  this being my first season, I wondered why the bilge pump had to cycle twice before it stopped. Oh well, new boat-new idiosyncrasies. Now, it will cycle up to ten times before it satisfies itself that it has removed the maximum amount of water. It appears that all of the water is not exciting from the discharge hose and therefore running back in to the bilge. I watched it cycle and I think it is fooling itself. As the water comes back to the bilge the pump senses the back flow and starts the cycle again. The drain hole from the front bilge compartment to the rear bilge compartment doesn’t help either. The water doesn’t all drain out of the front compartment  before the float switch cycles off (to the bottom position). It keeps draining through the hole. This combined with the returning water from the drain hose seems to work against the float switch. It appears as if the rush of water simulates a rising water level.
 There is not a lot of water in the bilge. Even after it has satisfied itself that the bilge is empty. I can initiate the whole procedure over again just by starting the pump manually and then switching it to auto.  Of course I think there is a loop in the hose with a siphon valve at the top. I repeat I think. I am not at the boat right now and forgot to look last weekend. To many other jobs on the go.
 
 Here’s the questions.
 
 1) What would make the cycling action repetition get progressively worse?  
 2) If there is a check valve in the system where would I look for it?
 3) If there is no check valve, is there a problem with putting one in?
 
 Thanks all.
 
 Mark

[rirvine]

Mark:
 
 The standard boat does not come with a check valve in the bilge pump discharge line.  Your problem is that there is a considerable amount of water in the line when the pump stops.  This water runs back into the bilge when the pump stops activating the switch again and the process starts all over again.
 
 Adding a check valve will solve this problem but could cause you other problems. Because the amount of water in the line behind the check valve causes too much back pressure (about 3 feet of water) for the pump to open the check valve after the first time.  
 
 My solution was to solve all the problems of how the water got into the bilge – mostly from around the keel bolts and various rainwater leaks.
 
 e

[Mark Wey]

Ray and Ron
 
 
 You might be right. I know where the leak is coming from. There is a leaky fitting on the hot water heater. I a m having a heck of a time trying to find a replacement. How ever I have been tied up with many other things, and have not had time to get serious about it. Sounds like I have to change my priorities. Last weekend I replaced the AC/DC panel. This weekend I guess I know what I have to do.
 
 Again thanks for everything. You folks sure make owning a C-34 a pleasure.
 
 Mark

[Mike Smith]

I don't know where I read this, probably Cruising World or Sail magazine, but here goes: The problem is that the main bilge pump operates on a centrifugal principal without a check valve and can never get the water in the hose completely out of the boat before the float switch bottoms out and turns the pump off.  The water in the hose and pump then runs back into the bilge.  The volume of returning water may or may not be sufficient to turn the pump back on to produce cycling but you still have water in the bilge.  The solution I read is to mount the main bilge pump and float switch on a platform slightly above the floor of the bilge and mount a small displacement pump and float switch on the floor of the bilge.  Snake the smaller diameter output hose of the displacement pump alongside the main pump output hose and install a small through hull fitting next to the main bilge through hull fitting. The small displacement pump and float switch will handle the relatively small amount water which returns to the bilge after the main pump turns off and the diaphram of the displacement pump will act as its own check valve after it turns off. The result is a dry bilge.
 
 Mike and Jan Smith
 S/V Breezer
 www.mikejansmith.com

[Ken Juul]

Rather than cut another hole in your boat, teeing into the A/C water output line is another option.  Putting in a slight hump or check valve will prevent any back flow of A/C water.

[kmorton16@comcast.net]

Hi Mark,
 I stopped the recycling in Trident - 1300 by installing a check valve.  Boaters world has them and it fits between the pump and the discharge hose. Prior to that I installed a larger volume pump. This is the 3rd or 4th year for the unit and it sure solves the recycling problem. A counter and flashing LED's have been added to keep track of the pump's operation. I plan to place the information in a Mainsheet article in the future.
 Ken Morton