My boat came with the three ballast pump motors attached to the transom. One was mounted with the pump head below the motor and the other two mounted with the pump heads above the motors. The problem with the head below the motor was that it was a pain to change the impeller. The problem with the pump head above the motor is that water inevitably drips into the motor and corrodes out the motor. The two motors that were below the pump heads were pretty severely corroded but surprisingly somewhat worked.
My project was to build HDPE shelves for the motors to sit on to eliminate both problems. Here is a picture of the center pump mounted already on a shelf with the starboard pump still mounted in the factory position.
Here's the lower bushing of one of the corroded motors.
Building the shelves was not complicated but I did have to ensure there was room for the pumps to sit on the shelves using the original pump mounting holes in the transom.
It was a little tight installing the shelves but it was well worth it. I did have to rotate the pump heads on a couple of the pumps to make sure water was still going in the right direction when I flipped the switches to fill/empty. The motor that had the pump head below it did not need a "reversal."
They look nice all in line. Next time I need to change impellers it will be an EASY 10 minute job.