"THE NURSE OF THE NAVY"
Just as a navy requires floating distilleries, floating coal stores
and floating docks, so does it find very important uses for a floating
workshop, which can accompany a fleet to sea and execute such repairs
as might otherwise entail the return of a ship to port.
The British Navy has a valuable ally of this kind in the torpedo depôt
ship _Vulcan_, which contains so much machinery, in addition to the
"auxiliaries" already described, that a short account of this vessel
will be interesting.
The _Vulcan_, known as "The Nurse of the Navy," was launched in
1889. She measures 350 feet in length, 58 feet in beam, and has a
displacement of 6,830 tons. Her bunkers, of which there are twenty-one,
hold 1,000 tons of coal, independently of an extra 300 tons which can
be stowed in other neighbouring compartments. When fully coaled she can
cruise for 7,000 miles at a speed of 10 knots; or travel at first-class
cruiser speed for shorter distances.
The most striking objects on the _Vulcan_ are two huge hydraulic
cranes, placed almost amidships abreast of one another. They have a
total height of 65 feet, and "overhang" 35 feet, so as to be able to
lift boats when the torpedo-nets are out and the sides of the vessel
cannot be approached. The feet of the cranes sink 30 feet through the
ship to secure rigidity, and the upper deck, which bears most of the
strain, is strongly reinforced. Inside the pillar of each crane is
the lifting machinery, an hydraulic ram 17-1/2 inches in diameter and
of 10-foot stroke. By means of fourfold pulleys the lift is increased
to 40 feet. When working under the full pressure of 1,000 lbs. to
the square inch, the cranes have a hoisting power of twenty tons. In
addition to the main ram there is a much smaller one, the function of
which is to keep the "slings" (or cables by which the boat is hoisted)
taut after a boat has been hooked until the actual moment of lifting
comes. But for this arrangement there would be a danger of the slings
slackening as the boat rises and falls in a seaway. The small ram
controls the larger, and the latter cannot come into action until its
auxiliary has tightened up the slings, so that no dangerous jerk can
occur when the hoisting begins.
The cranes are revolved by two sets of hydraulic rams, which operate
chains passing round drums at the feet of the cranes, and turn them
through three-quarters of a circle.
On the _Vulcan's_ deck lie six torpedo boats and three despatch boats.
The former are 60 feet long, and can attain a speed of 16 knots an
hour. When an enemy is sighted these would be sent off to worry the
hostile vessels with their deadly torpedoes, and on their return would
be quickly picked up and restored to their berths, ready for further
use.
[Illustration:
_Photo Cribb._
A 12-inch gun being lowered into its place in the turret of a warship
by a gigantic sheer-leg crane, one leg of which is partly visible on
the left of the picture.]
The cranes also serve to lift on board heavy pieces of machinery from
other vessels for repair.
Down below decks is the workshop, wherein "jobs" are done on the high
seas. It has quite a respectable equipment: five lathes, ranging from
15 feet to 3-1/2 feet in length; drilling, planing, slotting, shaping,
punching machines; a carpenter's bench; fitters' benches; and a furnace
for melting steel. There is also a blacksmith's shop with an hydraulic
forging press and a forge blown by machinery; not to mention a large
array of tools of all kinds. Special engines are installed to operate
the repairs department.
The _Vulcan_ also carries search-lights of 25,000 candle-power; bilge
pumps which will deliver over 5,000 tons of water per hour; two sets of
engines for supplying the hydraulic machinery; air-compressing engines
to feed the Whitehead torpedoes; a distilling plant; and last, but by
no means least, main engines of 12,000 h.p. drawing steam from four
huge cylindrical boilers 17 feet long and 14 feet in diameter.
Altogether, the _Vulcan_ is a very complete floating workshop,
sufficiently speedy to keep up with a fleet, and even to do scouting
work. Her guns and her torpedo craft would render her a very
troublesome customer in a fight, though, being practically unarmoured,
she would keep as clear of the conflict as possible, acting on the
offensive through the proxy of her "hornets." She constitutes the first
of a type of vessel which has been suggested by experts, viz. one of
high speed and unarmoured, but capable of carrying a swarm of torpedo
boats which could be launched in pursuit of the foe. Even if 50 per
cent. of the craft were destroyed, the price would be small if a single
torpedo were successfully fired at a battleship. The naval motor boat,
to which reference has already been made, would just "fill the bill"
for such a cruiser; and in the event of a score of them being dropped
into the water at a critical moment, they might easily turn the scale
in favour of their side.