This morning I attached the GDL51 to the front side of the sub-panel. Since the battery backup unit was mounted to the aft side of the sub-panel, I fabricated two attachment strips to ease installation. The strips have #8 nutplates riveted to them which simplifies access to the limited space; particularly the top two screws.
Also installed the GD-40 Carbon Monoxide Detector. This unit is very light so I simply mounted it to the backside of the PFD. I cut a 1/2" bar of aluminum, drilled four holes for mounting screws, attached the CD-40 to the bar strip & then cantilevered the assembly off the two cooling fan's top two screws. I also attached two bumper pads to the bottom backside of the unit to ward off vibration.
