Every-day Science: Volume 7. The Conquest of Time and Space

by Henry Smith Williams; Edward Huntington Williams

In diving, the Holland type of boat takes in sufficient water ballast to lower it to the surface of the water. The horizontal rudders are then brought into use causing it to descend to the desired depth, and keeping it at an approximately uniform distance from the surface while running submerged. By this arrangement the boat can dive very quickly, requiring only a matter of eight or ten seconds for reaching a depth of thirty feet. Record plunges have been made in less time than this.

The armament of the Holland boat was originally designed to consist of three tubes, two of which were for throwing aërial torpedoes and shells, and the third for discharging Whitehead torpedoes. One of these aërial guns was placed in the bow, and one in the stem; but later the stern tube was abandoned. The bow gun was designed to discharge projectiles a distance of about one mile, such projectiles weighing something over two hundred pounds and carrying one hundred pounds of gun-cotton. The tube for discharging the Whitehead torpedo was practically the same as the submerged tubes in use at present on battle-ships.

Although this Holland is now the type of diving boat most familiar to the majority of people, and the one in use in several navies, it should not be understood that the Holland boats were the only successful submarines constructed up to this time. France and Russia had produced successful diving boats; and in America those invented by Simon Lake, some of which are used for wrecking and salvage work as well as for war purposes, have proved quite as practical as the Hollands. In recent tests of these two types by the United States Government the Holland boats showed themselves to be slightly superior to the Lake boats in certain particulars, but the margin of superiority was a very narrow one.

The boats of the "Octopus" type are strictly speaking "diving boats," while the Lake boats are of the "even-keel" type. These terms refer to the method of submergence, the diving boats changing their horizontal trim when submerging, while the even-keel boats retain their horizontal trim, or nearly so.

The Lake boats have some features not usually embodied in other submarines, since some of the boats are designed for purposes other than warfare. Thus, they are equipped with wheels, or buffers, on which they can roll along the bottom of the ocean or bay. In the bow is an air-tight compartment with an opening in the bottom through which a diver can emerge and work on wreckage, or laying and disconnecting mines. These boats have also a safety device in the form of a detachable keel weighing several tons. In case of accident, when it might otherwise be impossible to rise to the surface, this keel can be detached simply by pulling a lever, thus giving the boat sufficient buoyancy to rise to the surface. This particular feature of the detachable keel is not peculiar to the Lake boats alone, some of the foreign submarines using a similar arrangement as a safeguard.

THE AMERICAN SUB-MARINE BOAT "CUTTLEFISH" IN DRY DOCK AT THE BROOKLYN NAVY YARD.

Technically speaking the name "submarine" is now used only as applying to those boats that are operated solely by electric power, have little buoyancy, and do very little running at the surface. The term "submersible" is applied to a submarine boat, actuated by electricity while submerged, but using gasoline motors for motive power while running at the surface. These gasoline engines are used at the same time for charging the storage batteries; so that the submersible is a much more practical boat than the submarine, and at the same time is quite as good a diver. Indeed, although many naval writers are very careful to make a distinction in the use of these terms, there seems little need of doing so, since only one type of boat—the submersible—is now considered practical. But as the word submarine is the older and more popular, it is used here to cover both classes except in specific cases.

For several years there were two classes of submarines under observation—those possessing no floatability when submerged, and those having some reserve buoyancy. The advantage claimed for the no-floatability class of boats is that, having no buoyancy, they are kept more easily at a certain depth below the surface of the water instead of tending to come to the surface constantly as in the case of boats of the other type.

But in actual practice the theoretical possibilities of such boats have not come up to the expectations of their advocates. For keeping the boat at a uniform depth, the most universally accepted method is by the use of horizontal rudders. The fact that the vertical direction of a boat may be controlled by horizontal rudders, when her buoyancy is small, has long since been established in submarine navigation; and the simplicity of this method naturally helps its popularity. If there were no shifting of weight in a submarine, or no wave disturbance, it would not be difficult to set the rudders at such an angle that the boat would travel for long distances at an approximately uniform submergence, the depth of submergence being indicated by gauges acted upon by the water pressure on the surface of the boat. And in actual practice it is possible to do this at the present time, part of the problem having been solved by automatic and other devices.