My backup (third) battery is under the nav seat. On the E381, with the galley to starboard and the nav station to port, that's conveniently right next to the house bank, so the cable run is short. I don't know if that's true of the 38-200.
We're supposed to have strong hold-downs, and at least passive ventilation even for AGMS.
Passive vent? woudl that be just a little louver metal vent venting to the cabin space? Or does it needs to vent outside? The setup on the 38-200 is reverse of yours with the galley on port and nav on starboard
I think so--simple vents. With AGMS I don't see it as critical anyhow. There are guidelines from--American Yacht Council or somebody. Surveyors might see it differently, but common sense works here. I don't have vents in my nav seat, and the tie-down for my twin Group 31s is weak given the bad attach points, so I just screw the lid down for offshore stuff. I do think big heavy batteries should fit very snug, so as to not move around at all in a heavy seaway.