In the original configuration of Leading Star, this room contained two 6'0" berths. We basically removed the lower berth and used the area to house two heat pump units (providing the boat with air conditioning and heating), diesel filters for the engine and generator, and various other mechanical equipment and tools. The upper berth is still servicable and the lower berth could be "reclaimed" ... but we wanted to have easy access to the engine, to facilitate easy inspection and maintenance of our key systems.
The photo below shows the aft part of the mechanical room, viewed from just outside the doorway (i.e., standing in front of the Nav Station). The cabinet on the right side of the photo contains the diesel filters (mounted on wall) and various other items. The silver insulation to the left of the cabinet is insulation around the ducting from one of the heat pumps.
The engine, located under the center cockpit, is accessable from this room (as well as a second access panel in the starboard passageway). There are storage lockers below the berths to starboard.