Adding an Engine-driven Bilge Pump

The boat originally came with just an anemic 2.8gpm electric bilge pump, which was also used for the shower sump in the aft head.  Because we could bail with a bucket faster than that, I decided to add a bigger pump.  While we could have added an electrical pump, their capacity is actually suspect with any kind of deep lift.  So, I decided to go with a powerful engine driven pump.  The Jabsco is good for an honest 26 gpm.

While it is true that an engine powered bilge pump requires the engine to be on, it is also true that once an electric powered pump exhausts the batteries, it too will require the engine (as well as the alternator).  In the mix, I decided that the engine powered pump would supply the capacity and reliability that I wanted.

Engine-driven bilge pump
The engine powered bilge pump can be seen at the right. It is activated by throwing a clutch.  The custom aluminum bracket is under the pump. The new sheave can be seen at the left.

The stock Yanmar comes with only one sheave on the main crankshaft.  Fortunately, Cascade Diesel of Seattle, Washington, offers a bolt on triple sheave as a stock item.

To hold the pump, a custom bracket was fabricated out of aluminum.  It was designed to be bolted on to the front of the engine, where Yanmar had thoughtfully provided some holes for just this purpose. The bracket was designed with a slot that allows the pump to be moved left and right in order to adjust the belt tension.

Top view of engine-driven bilge pump
A (fuzzy) view from the top of the pump.  The adjustment bolts that allow the belt tension to be adjusted can be seen.

Hal Thesen of Lummi Island, Washington, did most of the installation.