[Tiara Open] 1993 3100 Open head question

[Ptikkala]

Question about head seacock location. Head isn't bringing water in (new in 2015 and little use since then). Mechanic on boat yesterday and we're guessing we may have a closed seacock but our hatch won't open all the way (at least not w/o 2 people) until we replace starboard batteries when we return in 2 weeks. When I look at schematics in owner's manual I don't see a seacock for the head, which doesn't make sense. Can someone tell me where it's located and if it's accessible from just opening the center engine room hatch?

And, yes, I know this sounds like a stupid question, but our mechanic was trying not to waste time looking for something that wasn't there. So, would just like to know if we should call him back before we return home and replace the batteries.

Thanks