I'll leave out the history (10 days of trying to find the problem) and start with what I now know for sure. The bilge pump in my Hunter 336 oscillates on and off continuously if there is just the right amount of water in the bilge. I just spent several days living on the boat and I observed this several times. Here's what's happening: when the water level in the bilge gets high enough, the float switch turns on the bilge pump. The pump then does what is supposed to do, it pumps the water out. When the water level in the bilge falls below the float switch lower limit, it turns the pump off. When the pump turns off, all of the water in the hose between the pump and the thru hull flows back through the pump and into the bilge. As luck would have it, this is just enough water to trip the float switch and turn on the pump again. This cycle continues until the battery runs down (when I'm not on the boat) or I take the float switch out of the bilge. If, on the other hand, I turn on the bilge pump with the manual switch and pump all of the water out of the bilge, the flow back water is not enough to trip the float switch. It seems to me that there are several ways to approach this problem: 1. Get a different float switch that has a bigger range between the "on" position and the "off" position. 2. Install a larger pump (not sure why I think this may work). 3. Install an anti-siphon loop in the hose (this won't work, because of the configuration of the boat there is no place to put a loop. 4. Install a smaller hose (less volume of water to flow back) 5. Install a check valve. My questions are: 1. Has anyone else had this problem? 2. Why do I now have this problem when I haven't had it for the past 7 years (I did install a new float switch this spring, but it was an identical replacement). 3. If any one else has had this problem, how did you fix it? Thanks, Tom
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Bilge Hose Backflow
Tom Everyone has this problem of backflow, but you just seemed to have found The Magic Point!!! for the new switch on your bilge pump. Your proposed solutions are all on the nose. With the following personal comments 1. Check valves have adherents and opponents. It'd stop your particular problem, but would lead to, as opponents say, yet another. Downsides: potential blockage, added flow restrictions, etc. I bought one, never installed it and finally figured if my goal was an absolutely dry (like let the spiders live there) bilge, I'd better work on that, rather than letting the water come in and just goofing around about how to get rid of it after it gets in!. I still haven't done that, but I sure notice the backflow. If there's never any water in there to begin with, why bother? It's, I know, a goal, but ALSO a reality because I actually know people who've done it! 2. Bigger pump probably won't help unless it's bottom line pickup location is physically higher (or lower) than the base of your existing pump. What's happening is that your switch and pump are now perfectly matched except for the backflow, and you've correctly figured out the reason for the issue. 3. Antisiphon loop and smaller hose - no need for either; smaller hose creates even greater restriction just where you need the least; antisiphon would only stop outside water from coming in thru the thru hull, but also create more pressure drop by extra hose to the loop itself above the waterline for the AS fitting. 4. You have a new float switch already, why spend any more $? The answer, it appears to me, could be very easy: put a shim under the float switch OR {that's OOORRR} raise the pump base with a shim. All you are looking for is to avoid that Magic Point!!! that you've somehow stumbled upon. (Even the new switch, if identical, would have a slightly different on and off point because of they way they're made - not finely tooled you can imagine.) When I say shim, start with 1/2" board, then 1" or a 2x4. Think about what you'd like best and least. A bit more water in the bilge all the time (higher pump) or more water in the bilge sometimes that gets pumped out less (higher float). Try looking at it sideways, like being a fish outside looking in (through your clear glass hull
and that should help explain. This seems to me to be the least intrusive and expensive answer, or at best a good first step to see if you can live with it. Good luck, any questions let us know. I'd be interested in knowing how it works. Stu
Tom Everyone has this problem of backflow, but you just seemed to have found The Magic Point!!! for the new switch on your bilge pump. Your proposed solutions are all on the nose. With the following personal comments 1. Check valves have adherents and opponents. It'd stop your particular problem, but would lead to, as opponents say, yet another. Downsides: potential blockage, added flow restrictions, etc. I bought one, never installed it and finally figured if my goal was an absolutely dry (like let the spiders live there) bilge, I'd better work on that, rather than letting the water come in and just goofing around about how to get rid of it after it gets in!. I still haven't done that, but I sure notice the backflow. If there's never any water in there to begin with, why bother? It's, I know, a goal, but ALSO a reality because I actually know people who've done it! 2. Bigger pump probably won't help unless it's bottom line pickup location is physically higher (or lower) than the base of your existing pump. What's happening is that your switch and pump are now perfectly matched except for the backflow, and you've correctly figured out the reason for the issue. 3. Antisiphon loop and smaller hose - no need for either; smaller hose creates even greater restriction just where you need the least; antisiphon would only stop outside water from coming in thru the thru hull, but also create more pressure drop by extra hose to the loop itself above the waterline for the AS fitting. 4. You have a new float switch already, why spend any more $? The answer, it appears to me, could be very easy: put a shim under the float switch OR {that's OOORRR} raise the pump base with a shim. All you are looking for is to avoid that Magic Point!!! that you've somehow stumbled upon. (Even the new switch, if identical, would have a slightly different on and off point because of they way they're made - not finely tooled you can imagine.) When I say shim, start with 1/2" board, then 1" or a 2x4. Think about what you'd like best and least. A bit more water in the bilge all the time (higher pump) or more water in the bilge sometimes that gets pumped out less (higher float). Try looking at it sideways, like being a fish outside looking in (through your clear glass hull
and that should help explain. This seems to me to be the least intrusive and expensive answer, or at best a good first step to see if you can live with it. Good luck, any questions let us know. I'd be interested in knowing how it works. StuThere's a very simple solution
A "dinghy bailer" and a bucket. There's not a bilge pump installation on the planet that can eliminate 100% of the water running back down from the top of the loop without risk of defeating the bilge pump altogether and sinking the boat. Try as we will to make 'em so, boat maintenance will never be fully automatic...there are just some things that that will always require a little effort. So if you want a dry bilge, there's only one way to have it: you're gonna to put a little effort into it. Route everything you can into a sump and keep the sump clean if you don't want it to stink...and accept the fact that the only way to get rid of the water the bilge pump leaves behind is a hand pump, a sponge and a bucket. I've been there...and finally just had to accept that part of closing up my boat each time had to include getting out the pump, bucket and sponge...pumping, mopping and dumping that d'd bucket overboard...and then putting it all back in the dock locker.
A "dinghy bailer" and a bucket. There's not a bilge pump installation on the planet that can eliminate 100% of the water running back down from the top of the loop without risk of defeating the bilge pump altogether and sinking the boat. Try as we will to make 'em so, boat maintenance will never be fully automatic...there are just some things that that will always require a little effort. So if you want a dry bilge, there's only one way to have it: you're gonna to put a little effort into it. Route everything you can into a sump and keep the sump clean if you don't want it to stink...and accept the fact that the only way to get rid of the water the bilge pump leaves behind is a hand pump, a sponge and a bucket. I've been there...and finally just had to accept that part of closing up my boat each time had to include getting out the pump, bucket and sponge...pumping, mopping and dumping that d'd bucket overboard...and then putting it all back in the dock locker.
Consider a second pump
If you're feeling like a bit of extra work, you might want to consider the virtues of installing a second, independent bilge pump complete with its own switch, tubing, etc. The beauty of doing this is that you can use a tiny pump with narrow tubing (so very little backflow) and your large electric pump only runs if you have a fast inflow. This idea comes up fairly often: I've added a link to a Sailnet article with one of the detailed writeups available.
If you're feeling like a bit of extra work, you might want to consider the virtues of installing a second, independent bilge pump complete with its own switch, tubing, etc. The beauty of doing this is that you can use a tiny pump with narrow tubing (so very little backflow) and your large electric pump only runs if you have a fast inflow. This idea comes up fairly often: I've added a link to a Sailnet article with one of the detailed writeups available.
the real problem is the dead battery
I'm not concerned about a little water in the bilge, what was happening was the continuously running bilge pump was draining the battery in less than a day. So, I either have to stop the oscillating or just remove the float switch. If there's a serious leak, the float switch, bilge pump, battery system is not going to save my boat unless I'm already on it. As Colin's article pointed out the battery is going to drain in only a matter of hours if there is a real hole in the boat.
I'm not concerned about a little water in the bilge, what was happening was the continuously running bilge pump was draining the battery in less than a day. So, I either have to stop the oscillating or just remove the float switch. If there's a serious leak, the float switch, bilge pump, battery system is not going to save my boat unless I'm already on it. As Colin's article pointed out the battery is going to drain in only a matter of hours if there is a real hole in the boat.
B.P. Backflow Reduction
TOM: You and the other responders have a pretty good handle on the situation. Further to your list of possibilities: 1. Different Float Switch - The typical B.P. level switch (<$25) is a great moneymaker for the marine electrician (they’re ‘crap’). I always recommend the substitution of an “Ultra Pumpswitch” (>$90), preferably c/’w “Alarm” (audible outside). 2. Larger Pump - Actually, you could use a SMALLER pump &/or discharge hose. This will permit less back-flow water (being smaller). Don Casey’s article (referenced by Colin) suggests this. Or you could install a (full flow)wye-valve, allowing two separate pump discharges. The first discharge would be full-diameter, full flow hose, and the second (manually selectable, as prudence dictates) could be reduced to a much smaller discharge hose, permitting much less back-flow. 3. Anti-Siphon Loop - won’t help this problem, as has already been pointed out. 4. Smaller Hose - Perhaps, See 2 above. 5. Check Valve - Don’t do it!!! To your questions: 1. Yes, everyone has this problem (to a greater/lesser degree). See Peggy’s reply. 2. Why now? There is no such thing as an “identical” replacement. The manufacturing tolerances on a $20 item are (understandably) pretty large. 3. How to fix it? See Casey’s article, and (2) above, and also “Darden” (Surveyor) has something on his website (cannot recall the URL). They all say the same thing. Smaller = less backflow (for convenience). Also see Peggy - no magic bullet. Finally: As noted - the dead battery is the most significant consequence. A permanently connected battery charger could keep the battery alive, and the pump available. There are good & plenty reason to NOT leave a charger ruinning untended. My recommendation: Unless the accumulated water poses a significant danger to the vessell, I'd: a) Install an 'always on' high water bilge alarm. b) Turn off the Bilge Pump when untended. Regards, & good luck, Gord May
TOM: You and the other responders have a pretty good handle on the situation. Further to your list of possibilities: 1. Different Float Switch - The typical B.P. level switch (<$25) is a great moneymaker for the marine electrician (they’re ‘crap’). I always recommend the substitution of an “Ultra Pumpswitch” (>$90), preferably c/’w “Alarm” (audible outside). 2. Larger Pump - Actually, you could use a SMALLER pump &/or discharge hose. This will permit less back-flow water (being smaller). Don Casey’s article (referenced by Colin) suggests this. Or you could install a (full flow)wye-valve, allowing two separate pump discharges. The first discharge would be full-diameter, full flow hose, and the second (manually selectable, as prudence dictates) could be reduced to a much smaller discharge hose, permitting much less back-flow. 3. Anti-Siphon Loop - won’t help this problem, as has already been pointed out. 4. Smaller Hose - Perhaps, See 2 above. 5. Check Valve - Don’t do it!!! To your questions: 1. Yes, everyone has this problem (to a greater/lesser degree). See Peggy’s reply. 2. Why now? There is no such thing as an “identical” replacement. The manufacturing tolerances on a $20 item are (understandably) pretty large. 3. How to fix it? See Casey’s article, and (2) above, and also “Darden” (Surveyor) has something on his website (cannot recall the URL). They all say the same thing. Smaller = less backflow (for convenience). Also see Peggy - no magic bullet. Finally: As noted - the dead battery is the most significant consequence. A permanently connected battery charger could keep the battery alive, and the pump available. There are good & plenty reason to NOT leave a charger ruinning untended. My recommendation: Unless the accumulated water poses a significant danger to the vessell, I'd: a) Install an 'always on' high water bilge alarm. b) Turn off the Bilge Pump when untended. Regards, & good luck, Gord May
A check valve solved it for me.
Before installing the check valve, the pump would cycle several times in five minutes, and when it did finally stop, the bildge was just below the threshold of causing the float switch to come on. Since installing the check valve, the pump came on once and I've not heard it again. Meantime, the bilge is nearly dry, with only about a pint of water in it. As Peggy recommended, I clean it out with a hand pump and sponge every time I come back to the boat. The reasons for not using a check valve are well known, but I installed a bronze (oversized) valve about a foot up-stream of the pump. It's been in there for awhile and works like a charm. However, I do keep an eye on it, and check the hoses and clamps about once a month. ~ Happy sails to you ~ _/) ~
Before installing the check valve, the pump would cycle several times in five minutes, and when it did finally stop, the bildge was just below the threshold of causing the float switch to come on. Since installing the check valve, the pump came on once and I've not heard it again. Meantime, the bilge is nearly dry, with only about a pint of water in it. As Peggy recommended, I clean it out with a hand pump and sponge every time I come back to the boat. The reasons for not using a check valve are well known, but I installed a bronze (oversized) valve about a foot up-stream of the pump. It's been in there for awhile and works like a charm. However, I do keep an eye on it, and check the hoses and clamps about once a month. ~ Happy sails to you ~ _/) ~
Thanks, Everyone
Thanks for all the information and suggestions. I installed a check valve (I know most people didn't like this idea) as a temporary solution. I'll put in a better solution when I haul the boat for the winter-it's so much easier to work on the boat in the yard than on a mooring. Thanks, again
Thanks for all the information and suggestions. I installed a check valve (I know most people didn't like this idea) as a temporary solution. I'll put in a better solution when I haul the boat for the winter-it's so much easier to work on the boat in the yard than on a mooring. Thanks, again
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