43 open keel bilge vs mid bilge

[bnr@dur-a-flex.com]

I have two bilge pumps in the engine room and was wondering if someone could confirm my theory.  One of them looks like a regular bilge pump, sits under the batteries and has a float switch, named mid bilge.  The other one is called the keel bilge and is a pump sitting on the port side of the port engine.  The breaker for this pump is normally in the off position and anytime I turn it on, the pump turns on.  My assumption is that the keel bilge is a larger pump designed as an emergency back up.  This would make sense because the design of the batteries being so close to the bottom of the bilge has always concerned me.

Can anyone confirm this for me?

Thanks!!!!