Small submarine vehicles present a particularly difficult and chanllenging engineering and human factors problem. The pioneer Italians discovered taht their magnetic compass-equipped mounted torpedoes had to be held by a special ballast near the surface to enable the pilots to hold their heads above water and do a visual approach. Rendezvous with the mother submarine, was so hopeless that each operation had to end with a surrender to teh enermy. The Kaiten suicide torpedo was a typical Japanese solution to the same problem