The Bilge Pump Switch Adventure

Saying “adventure” always makes it sound like more fun right?  Well this wasn’t too much fun, but it was necessary, and I’m glad we got it fixed.  Remember back in this post when I mentioned the bilge pump switch not working?

The bilge is where the water collects in the bottom of the boat.  Ideally you don’t want too much water collecting down here on a day to day basis, but there are various parts of the boat that leak a little, some by design and some not.  Every boat has one of these, and there is a switch and a pump in the bottom of the bilge so that when the water gets high enough the pump kicks on and sends it outside the boat.

Here’s a highly sophisticated diagram of how the bilge is set up on our boat.  The squiggly line going into the bottom of the bilge (under the engine) is the switch and bilge pipe.  The actual pump is mounted up on the wall next to the engine.  As you can see, half of the assembly sits in the “impossible to reach” zone.  The bottom of the bilge is maybe 4 feet under the engine.


So this is a side profile of the bilge, but if you were to look at it head on it is very narrow at the bottom, maybe 8″ wide at most.

Most float switches are mounted to the bottom of the bilge and have an arm that floats up, like this.

Image result for bilge float switch
A typical bilge pump float switch.

However, since you can’t get anywhere close to the bottom of the bilge in our boat to mount a switch like this, the previous owner used a sump pump float switch.  This isn’t typically what you would see in a boat, but I like it, it’s simple and effective (and probably cheap too, since it’s not “marine”).  The entire plastic housing floats and there is a contact switch inside, as the bilge fills with water once the switch is close to vertical it activates the bilge pump, and as the water level goes down it turns it off.

Image result for sump pump float switch
A household sump pump float switch.

However, since the entire plastic casing floats, and seemed to float in whatever direction it wanted to, the float switch kept getting stuck against the sides of the bilge, either in the off (didn’t come on when it was supposed to), or on position (didn’t turn off when the bilge was dry).  This isn’t as disastrous as it sounds because we have a backup bilge pump that kicks on when the bilge is a little more full, but then where is the backup for the backup?

So to get it out, I had to snake the semi-rigid plastic tube out of the bilge in between the bottom of the boat and the bottom of the engine, which involved lots of hanging upside down.

Fixing the bilge pump switch
Playing in the engine room.

Once out, I zip tied a small piece of PVC tube to the assembly, at just the right spot so the bilge pump switch would rest against it.  My hope was that this would give the pump just enough tilt so that as the water rises in the bilge it will float up in the right direction.  I dropped the whole assembly back into the bilge, and hooked everything back up.

Bilge pump switch solution
PVC pipe zip tied to the bilge pump float switch / pipe assembly.

To test it, I used a water hose to fill the bilge a few times, everything seemed to function fine.  However I thought the current of the water rushing out of the hose might be affecting the results, so I turned it down to a trickle and ran it through 2 more On/Off cycles, after which I was satisfied.  It seems to be working so far, in the 5 or so days we’ve had it rigged up this way it has turned on and turned off at exactly the right times.

2 thoughts on “The Bilge Pump Switch Adventure”

  1. I’m not sure if I should comment here or on facebook, but I am so glad that you are journaling and publishing your experience. I’m hoping you’ll swing by Houston so we can at least visit you and float around the Gulf for a couple of days before you travel the whole world.

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