I'm lucky in that the two huge, gas-spring assisted easy lift hatch sides [whose leading edges meet together in center of salon sole] are each piano hinged on their outer edges. Although I've not tape measured the opening by length and width... my guestimate is the opening provided by both hatches [with no center beam] amounts to around 6' x 5'. Berber carpet lays uncut over recessed piano hinges and under trim that borders hatch edges. When closed the hinges are non apparent and the hatches other three edges are bordered with carpet trim.
When both are pulled open [and then standing upright] they provide grand expanse over the engines as well as fairly ez access to most other equipment; e.g. batt bank toward aft, two 100 gal tanks to either side and gen set toward bow.
Slotted teak wood walk-way between engines with stand-up room galore.
It is a bit of a stretch to get directly over top of the tranys and can also be same for topping off the rear most wet cells on batts.
There is also room in multiple areas of the engine compartment for relatively ez access to items such as pressure water pump, water heater, trim tab hydraulic pump and its reservoir, batt charger. etc
I've had a few marine professionals get into out Tolly's engine compartment for various reasons. Each mentioned the expansive room and great layout.
MOF... when Linda and I were first aboard this boat [and in a short time of looking we realized this was/is the boat for us] I was standing on the engine compartment's teak walk-way when we winked at one another.
The big, stand-up engine compartment is one of many reasons we own this 1977, 34' Tollycraft tri cabin.