In spite of the many years that have passed since this competition and in spite of the tremendous progress that has been made in submarine construction these are still the essential requirements necessary to make a successful submarine boat.
The designs submitted by Mr. Lake provided for a twin-screw vessel, 80 feet long, 10 feet beam, and 115 tons displacement, with 400 horse-power steam engines for surface propulsion and 70 horse-power motors for submerged work. The boat was to have a double hull, the spaces between the inner and the outer hulls forming water ballast tanks. There were to be four torpedo tubes, two forward and two aft.
In an article published in 1915 in _International Marine Engineering_, Mr. Lake says about his 1893 design:
The new and novel feature which attracted the most attention and skepticism regarding this design was (the author was later informed by a member of the board) the claim made that the vessel could readily navigate over the waterbed itself, and that while navigating on the waterbed a door could be opened in the bottom of a compartment and the water kept from entering the vessel by means of compressed air, and that the crew could, by donning diving suits, readily leave and enter the vessel while submerged. Another novel feature was in the method of controlling the depth of submergence when navigating between the surface and waterbed. The vessel was designed to always submerge and navigate on a level keel rather than to be inclined down or up by the back, to "dive" or "rise." This maintenance of a level keel while submerged was provided for by the installation of four depth regulating vanes which I later termed "hydroplanes" to distinguish them from the forward and aft levelling vanes or horizontal rudders. These hydroplanes were located at equal distances forward and aft of the center of gravity and buoyancy of the vessel when in the submerged condition, so as not to disturb the vessel when the planes were inclined down or up to cause the vessel to submerge or rise when under way.
I also used, in conjunction with the hydroplanes, horizontal rudders which I then called "levelling vanes," as their purpose was just the opposite from that of the horizontal rudder used in the diving type of vessel. They were operated by a pendulum controlling device to be inclined so as to always maintain the vessel on a level keel rather than to cause her to depart therefrom. When I came to try this combination out in practice, I found hand control of the horizontal rudders was sufficient. If vessels with this system of control have a sufficient amount of stability, you will run for hours and automatically maintain both a constant depth and a level keel, without the depth control man touching either the hydroplane or horizontal rudder control gear. This automatic maintenance of depth without manipulating the hydroplanes or rudders was a performance not anticipated, nor claimed in my original patent on the above-mentioned combination, and what caused these vessels to function in this manner remained a mystery, which was unsolved until I built a model tank in 1905 in Berlin, Germany, and conducted a series of experiments on models of submarines. I then learned that a down pull of a hydroplane at a given degree of inclination varied according to its depth of submergence and that the deeper the submergence, the less the down pull. This works out to give automatic trim on a substantially level keel, and I have known of vessels running for a period of two hours without variation of depth of one foot and without once changing the inclination of either the hydroplanes or the horizontal rudder.