Sorry for the delay FrankEscalle. The hatch is under the fuel tank. That area is perfect for battery placement and creating a hatch makes it easier to get to. You can also use it to add lead weights if you need. You can see where I had some, but removed them later once I started adjusting the CG. Just make sure that you epoxy or use CG to seal the wood inside the compartment. This should be done anyway even if your don't make a hatch. Hatch just makes it easier. You can see how it is held in place with four small screws. Pictures can say a 1000 words.

I have attached some photos of my hatch. Let me know if you need any more photos or anything.