Submarine Warfare, Past, Present, and Future

by Herbert C. Fyfe

None of these boats used the principle which Mr. Nordenfelt applied to pull his boat down by mechanical means, while relying upon its always retained buoyancy for rising; so that if the mechanical apparatus failed the boat rose at once to the surface. Again, they did not have the tendency to steadiness given by the two forces of constant pulling down by the vertical screws, acting all the time, whether still or moving, against the pulling upwards caused by the buoyancy.

Mr. Nordenfelt considered it most dangerous to rely upon a detachable weight in case of emergency, as the apparatus for detaching it would be always liable to fail. He confessed that he could not imagine how the longitudinal instability of a submerged boat could possibly have been satisfactorily controlled by any of the means applied to the previous boats. Even Goubet’s system of moving water or weights fore and aft inside the boat must act more slowly and cause more diving and oscillation than his rudders which always remained in the horizontal, and thus controlled the slightest tendency of the boat to get out of the longitudinally horizontal position. He considered it absolutely essential to keep the boat horizontal when moving, as he believed that any inclination downwards with the impetus of a heavy boat would almost to a certainty carry the boat below its safe depth before it could be effectually counteracted by shifting weights.

The reason which led Mr. Nordenfelt to construct his submarine boats was the almost insuperable difficulty in carrying the Whitehead and Schwarzkopf fish torpedoes with any degree of certainty up to the short distance at which they could be considered infallibly effective. It seemed to him that a much greater chance would be given for carrying the torpedoes within striking distance, if, instead of trying to rush the distance by many boats, all the time exposed to the destructive fire from machine guns, he could carry the torpedo secretly up to this distance without the probability of being seen at all, and without any probability of being struck by the enemy’s shot even if seen.

The tactics to be adopted by his submarines in action were thus laid down by Mr. Nordenfelt. Out of sight of the enemy the vessel ran on the surface with its cupola and about three feet of its turtle back out of water, but by forced draught, blowing out its smoke under the surface. When she arrived within such distance of the enemy that she might be discovered, she descended into the water so far that the cupola alone appeared above the waves, this was done by taking in water into the cold-water tanks sufficient to reduce the floatability to what the horizontal screws were capable of overpowering. The “reduced floatability” was never done away with, but the descent from the “awash” position was effected by starting the vertical screws, thus overcoming mechanically the buoyancy of the boat, which was pulled down to a less or greater depth depending upon the speed given to the screws.

The three main points in Mr. Nordenfelt’s system on which he laid special stress were these:

1. That by using water as the means of storing up energy he was in possession of a reservoir which could never get out of order, and which could be replaced at any hour in any part of the world, and without any extraneous assistance from shore or other ships. The reason of all others which at once decided him to adopt the hot-water system was the enormous factor of safety obtained by his being able to blow out, by steam pressure without the use of machinery, large weights of water which would lighten the boat and counteract any leak likely to occur. Mr. Nordenfelt had little faith in electricity as a motive power, which is not surprising considering the accumulators then in use.

2. The submerging the boat by mechanical means: Mr. Nordenfelt was convinced that previous attempts had proved unsuccessful, mainly because either they depended upon varying the displacement of the boat by taking in water to submerge her and to regulate the depth at which they desired to operate, or they descended by steering downwards. His objection to the first-named method of descending, by taking in water and thus increasing the specific gravity of the boat, was that practically there was no difference in the specific gravity of water on the surface or at 50 feet depth; thus when the boat had lost its buoyancy at the surface it had also no buoyancy at any given depth, and the risk was thus very great of suddenly descending beyond a safe depth.

3. The horizontal position Mr. Nordenfelt found to be a sine qua non for a submarine boat.

When Mr. Nordenfelt built his boats electric accumulators were very much inferior to those of to-day; no designer of an under-water vessel would think nowadays of using the steam given off by heated water for under-water propulsion. As to his theory that a submarine boat must always descend on an even keel, this has since proved to be entirely erroneous; the modern diving torpedo boat goes down at an angle and is brought to the horizontal position at the required depth either automatically or by hand-worked mechanism.