Balt 25 ft cabin cruiser batterys

Question

i am trying to locate the batterys on a friends 25 ft cabin cruiser they are really elusive my friend thinks the boat manufacturer is balt thes batterys have not been serviced since the boat was new that was now three years ago and the boat only gets used in the summer season so they will probably be due a top up of electrolyte ar at least a charge but due to being unable to locate them we are unable to even inspect them even the engineer for the boat safety certificate was unable to locate them i have googled for the manufacturer hoping to find them so i could approach them directly but no joy