Our 25′ Contender test boat came from the factory with only one bilge pump. And even though a bilge pump is not marine electronics per se it is still an extremely important piece of marine electrical gear that we cover in our reports.
After much research we determined this single pump approach was inadequate for a boat of this size and use.
The Contender bilge is a single compartment and the original pump was properly located just forward of the transom.
Still, with mostly offshore usage in mind and large diameter through-hull fittings to service the boat’s in-deck bait tank the need for more pumping capacity was indicated.
To remedy the inadequate pumping capacity we elected to replace the original bilge pump and add a second.
The additional pump provides a backup pump and increased capacity in the event of a single pump failure or emergency.
Testing Bilge Pump Capacity
This re-evaluation of our test boat led us to run a full review of bilge pumps currently on the market. First, we devised a test procedure, then we divided the pumps into groups based on their advertised capacity.
Test results let us pick the best pair of pumps for our Contender. We planned for a total installed pumping capacity in the 2000 to 3000 gallons per hour range. Adding a second pump required fitting another pump outlet, in addition to the one already installed.
We finally settled on a total capacity figure of 3000 GPH based on the size of the seacocks installed in the boat. If one happened to break clean off and start flooding the bilge with water, the two pumps together should be big enough to keep up with the incoming water long enough to give us time to find the hole and plug the leak.
A smaller main pump backed up by a larger secondary pump minimizes our everyday electrical power usage yet yielded our desired combined GPH rating.
Bigger Boat, Bigger Pumps
In a larger vessel with bulkheaded compartments, each separate area should have both a primary and backup pump installed.
Any retrofit or replacement pumps must be properly sized for both the vessel and the bilge compartment they will drain.
Power consumption, GPH rating, outlet pipe diameter, and physical pump size must all be taken into consideration when selecting a pump.