If you have played with boats much, you know that the least reliable item on board is likely to be the pressure switch on the fresh water pump. To make matters worse, these are usually difficult to change.

We have been averaging a year of use on our pressure switches, and a year ago decided to install an industrial pressure switch. But it wasn't until a recent failure during Steve's evening shower that action was initiated on this long overdue project.

This is a "Square D" pressure switch, connected to a schedule 80 plastic PVC "T", ready to insert into the pressure line just after the pump.

In case you are taken with this concept, the above photo shows the ordering data.

An oversized look at the guts of the switch. There are two sets of contacts, each with many times the surface area of the usual marine pressure switches. You can use the two sets in parallel, or save one set for later use. The contacts can be cleaned with a flat file. The springs are used to set the cut-in and cut-out pressure.

Switch installed. It works great, and the pump is operating at a much higher flow rate, indicating the old switch probably had a voltage drop across it, reducing voltage and therefore motor speed.

Switches like this can be bought in industrial supply houses for about US$35.