|Holland Submarine Number 1 Exterior Details / 07DivingPlane
Nice reproductions by the Intrepid Museum staff. On Gary McCue's site he writes that if they were defected downwards with any kind of positive buoyancy the sub slowed to a crawl. It was not an efficient design for a submarine and Holland learned from that. When you think about it, with the diving planes deflected downwards and the hull at a state of positive buoyancy, if the sub is submerged and the propulsion ceases, the sub will slide backwards as it rises towards the surface.