Automatic bilge pumps come in different types, and in this video we show you the differences so that you can choose the right automatic bilge pump for you. The idea of an automatic bilge pump is that it senses when to turn itself on an off depending on whether you have water in your bilge that needs pumping out, but there are a couple of different ways in which automatic bilge pumps do this sensing.
Just to be clear we are talking about electrically operated bilge pumps here, rather than the ones with a handle that you pump the hard way, but within the category of electric bilge pumps there are the manual type where you have to manually flick a switch to turn the motor on and off, and there are that automatic type of bilge pump which have the ability to sense when to turn the motor on and off depending on what water level in your bilge.
The bilge pumps featured in this video, and many others can be purchased from the following link:
www.boatfittings.co.uk/c/mari...
In general the manual type of electric bilge pump has 2 wires, and the automatic type has 3 wires, for a detailed description how to wire bilge pumps please take a look at our article here:
www.boatfittings.co.uk/how_do...
Automatic bilge pumps come in different types, one type has a built in float switch, so when the water level in your boat bilge rises it lifts up the built in float and at a certain point the float activates a switch which turns on the bilge pump motor and then the bilge pump keeps pumping until the water level has been lowered.
The other type of automatic bilge pump does not have a float switch, instead it uses electronics to figure out if there is water in the bilge. Typically what happens is that every so often (eg every couple of minutes) the electronics turns on the bilge pump motor for a test. If water is in the bilge the motor will take more electrical current than if there is no water in the bilge - in this way the electronic ‘brain’ inside the bilge pump can decide if it needs to pump water out, or if it can go back to sleep again for another couple of minutes. If this type of automatic bilge pump does detect water it will keep on pumping until the water has gone and it starts trying to pump air, then it turns off and waits again.
There are advantages and disadvantages of these different types of automatic bilge pump. This float-switch type of bilge pump has the advantage that until it becomes activated by the water level, it sits doing nothing at all, so it doesn’t use any electrical energy and it doesn’t make any noise until it is needed. One possible disadvantage (though in our opinion not very significant) is that it has more moving parts, and therefore in some ways has more to go wrong (eg if the float switch go jammed). That said, the float switch is contained within the housing of the pump so is less likely to get jammed by random debris that finds its way into your bilge (rags, bits of rope, beer bottle tops etc.) than an external float switch would be.
The electronic type of automatic bilge pump has less moving parts which can be considered an advantage. A possible disadvantage is that what ever the case it is going to turn itself on every so often to test if it can detect water. If you are sleeping on the boat you might then want to turn off the bilge pump overnight (and remember to turn it on again in the morning) to avoid it waking you or disturbing the peace.