Since this is a flying boat this might be more appropriately called the Bridge. Much of the equipment was test equipment for the initial test flights and high speed taxi runs. The skin at the top of the ceiling was approximately 1/4 inch thick. The skin thickness varied througout the ship with thicker skin for the boat hull and thiner for the top of the aircraft. All the ribs are made of wood up until the nose area, this area was made of metal. The thin stips of metal that run the length of the deck are stress sensors, if the aircraft flexes too much they will break indicating a potential problem. They were part of the flight test equipment.