There are some general ideas. Either hatch, the closer to the middle of the boat, the bigger the hatch can be and the easier it is to fit things through it. Of course the bigger the hatch the easier it is to leak. If the hatch is in the middle of the storage compartment it's easier to reach the ends, everything is a trade off. For the forward hatch it's usually placed right in front of the bulkhead because the storage compartment at the front is usually pretty small to start with and to get any use it's handy to reach the widest and deepest spot that part furthest aft.

Bill H.