These present handicaps need not be permanent ones, and there is no more reason why a submarine should not take on fresh stores in the open sea than a surface vessel. Indeed, a submarine should be able to replenish her fuel tanks and to ship provisions under some circumstances even more securely than its rivals that run upon the water.
In short, a submarine should be capable of sinking to the sea-bed and there, beyond the reach of its foes, of drawing new strength, so to speak, from a suitably designed submergible supply boat. This scheme is not at all visionary. In part it has already been done in the past by vessels planned by me for commercial work, and there is no inherent difficulty in modifying both the military submarine and its revictualling consort so that they can thus function in unison for the purpose of giving the fighting undersea boat a wider field of action.
While the torpedo-boat destroyer, the submarine's logical pursuer to-day, is battling with wind and wave, jarring well nigh her sides out, and hunting over the tumbling seas for elusive periscopes, the submarine can lie in ambush upon the ocean-bed if the water be not too deep, or at rest at any desired depth, held in suspension between the surface and the bottom by her anchors, thus conserving her energies so that when she does rise for a peep through her observing instrument she can strike more certainly with all of the sinister force of her chosen weapon of attack. She can lurk in wait for her quarry not only for one day but for weeks at a time, especially when sand banks a hundred feet below the surface offer the needful haven.
What I propose is to provide every seagoing submarine with one or more mobile submersible bases of supply in the form of boats without motive power of their own which can be towed by the military under-water boat and sunk upon the sea-bed at convenient points where they will best suit the purposes of the subaqueous torpedo vessel. Naturally you ask what would happen if submarine scouts should sight a submarine towing a convoy of this sort. Wouldn't the submarine have to desert her supply vessels and sink alone beneath the surface? My answer is no.
Of course, this assumes that the submarine at the time is traversing waters that are not too deep for her to go to the bottom. She would take her tender or tenders down with her under such circumstances, for the supply boats would be built to stand safely the test submergence of the military submarine; that is, a depth of two hundred feet. The question may arise as to how I can control the sinking of the crewless consorts, holding as they would only supplies, and having none of the operative mechanisms that constitute a necessary functional part of the fighting undersea boat.
This is illustrated by the method with which I controlled the submergence of a tender with which I salvaged the coal from a sunken barge in Long Island Sound years ago. That cargo boat had tanks into which water could be admitted from the sea, and certain of the inlet passages were closed by means of check valves which were automatic, seating themselves by the tension of springs. In order to submerge the boat it was only necessary to admit water purposely and to open a valve on the deck for the escape of the air as the water entered.
To refloat the tender after it had reached the bottom and was loaded, a diver went from the submerged Argonaut by way of the diving compartment and attached a hose to the deck vent. This hose was then connected to the compressed-air flasks in the submarine. The air was blown down through the pipe into the ballast tanks and the water forced outboard, past the check valves that yielded in that direction, but reseated and closed themselves as soon as the air pressure stopped. In this fashion buoyancy was reacquired and the tender rose to the surface.
Of course, the initial sinking operation required the presence of someone in a small boat alongside the tender which I have just described. This would not be feasible in the case of the military supply boats I have in mind. These must be made to sink by suitable controlling devices manipulated from within the military craft, but in principle the cycle would not differ from that which I have outlined.
The deck valve allowing the air to escape from the tanks and the inlets admitting sea-water could be operated by suitable electrical mechanisms, and, once opened, the sea-water would enter and destroy the reserve buoyancy, thus causing the tenders to sink. Again, compressed air supplied from the submarine or compressed air carried by the supply craft themselves could be turned on by electrical control, and the boats brought to the surface at the will of the military commander.