I just discovered a space built into the Manatee for running a/c heat ducts or wires, etc. I found it while disconnecting a a/c flex duct in the stateroom. See the photo, it is above the duct outlet and runs from side to side, probable 16" x 24" area. Good to know if your re-wiring, running flex-ducts, etc. If you open the hanging locker and reach up you can see the height of the plenum area.