T&T: Bilge back flow problems

[John Baker]

Well, we went on our little trip over the weekend.  It was somewhat annoying to find out that water was finding its way into the bilge.  I think in the rawest purest since of the definition of the word "boat", it is something that floats and keeps the water on the outside.  So I don't care how nice your "boat" is, if it aint succeeding in this regard, it aint much of a boat.  Well, there I was with the high water alarm chirping at me.  I guess this was the most irritating thing because water would find its way back there into the bilge "compartment'(defined by stringers and such) and couldn't seem to find its way back to the lower water bilge pumps.  So while water was backflowing from the outside thru the pumps and into the bilge, obviously, the bilge pumps were doing their job and throwing that water right back out....except that water in the back corner where the high water alarm and pump is.  It has one of those holes in the stringers(I forget the proper word for those
 holes) but it is higher than the float switch for the emergency pump.
   
  So what does the sensible boater do when water is finding its way into his boat?  Why he disconnects the bilge pumps and plugs up the hoses!!!  I have 3 regular pumps with a giant emergency pump.  I disabled 2 of the pumps.  I just couldn't find it in me to do all 3 and I obviously left the emergency pump on line.  This did stem the flow greatly but it still did trickle in from the one active pump.  The bilge pump outlets are about 2-3 inches above the waterline while the boat is at rest but they go under water while under way(or at least a stream of water flows over the holes).  The plumbing comes straight from the thru-hulls and goes DOWN....never going any higher than the holes themselves.  I had never really noticed this because I have never really ran this boat for long periods of time(greater than 2 hours).  So while I did wonder where the water was coming from in a boat with a dripless packing gland, it was always very little.  BTW, all of the info above was thru
 lotsa problem solving while not sleeping staring at the ceiling.  It was taking on water only while underway and not while at rest.  The obvious culprits got consideration before coming to my final conclusion...which I am not 100% sure because I did not isolate all pumps.
   
  The question would be what is the fix.  Just simply put a loop above the "underway waterline".  How far uphill can a Rule 1100gpm pump?
   
  What is the theory of checkvalves/flapper valves in the bilge line?
   
  And what would be the thought of putting on/off valves in line(on the normal pumps only since the problem lay with them) and just closing them while underway and opening them whenever needed....which, theoretically in this boat should be never unless something abnormal is going on.  These should be reliable and controllable while a check vavle may unknowingly fail.   We all check our bilge while underway, right?  I was checking the bilge at least every 30 minutes on this trip...which made it tiresome especially when I wasn't sure if I was in a boat(by the pure definition above) or a future fish condo...okay, I am being a little melodramatic here.  My point is that it does not make for a relaxing trip when water is finding its way into your boat.
   
  Trawler on,
  John

       
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