The Nautilus, as a matter of fact, was something vastly more than a toy or experimental model. It possessed real offensive powers, and a fleet of them, as Fulton proposed and as the British navy officials feared, would have been able to do real havoc. In estimating the offensive power of Fulton’s design, the picture of the modern submarine must be kept out of sight. The latter is called on to meet conditions of mechanical development and types of hostile vessels that are as much in advance of those existing when Fulton lived, as is the complicated mechanism of a present-day submarine over the hand-driven propeller proposed by him.
At the beginning of the last century, a ship-of-the-line was a very unwieldly affair. She was bluff bowed and high sided and consequently could be handled satisfactorily only when “off the wind.” Even under these favorable conditions, speed was comparatively slow. With a light wind, especially with a light adverse wind, she could make but little headway. Such a wind rendered capital ships practically helpless. That they were not destroyed by the opposing force was because at such times the opposing force was helpless too. A boat that had offensive power of attack and had means of locomotion enough to overcome tidal currents would have been an effective menace. As Fulton pointed out, the only measure of defense by a large vessel at anchor would lie in a cordon of small boats. But a boat fully, or even partially, submerged would have had an excellent chance to get through a cordon and destroy her prey. In spite of the limitation of speed and cruising range that today would condemn any such boat as absolutely worthless, these limitations were sufficiently generous when compared with the status of naval architecture that prevailed in 1800–1806 to make Fulton’s submarine, when he proposed it, a factor of actual and positive value.
If that can be said of the Nautilus, all the more it is true of the design that he submitted to the British Government. Between the Brest experiments in 1801 and his proposals in 1804, as evidenced by his “Drawings and Descriptions,” it is clear that he had given the matter considerable thought and to some purpose. The specifications as submitted to the British agent called for a boat 35 feet long and 10 feet beam as compared with the similar dimensions of the Nautilus of 21 ft. 3 in. and 6 ft. 4 in., respectively, giving at least three times the tonnage. It was to carry a crew of six instead of three men with provisions sufficient to enable her to be kept at sea for 20 days. The offensive capacity was 30 submarine bombs (or mines) as against a single trailing one with the Nautilus. The vessel designed for the British Government was a real sea-going boat that could independently navigate the Channel while the little Nautilus could not venture far from land or from some large vessel acting as a base.