528

THE COLLIERY GUARDIAN.

March 16, 1917.

of the bias at a distance of 5 ft. apart. Beneath the
gates, and on each side of the bins, is a track for
movable chutes, which deliver to bags or skips, either
direct to vessels or on to the pier deck; and in this
manner 200 tons per hour can be delivered from storage.
It should be mentioned that two thermostats are provided
in each bin, these being suspended in galvanised iron
pipes, 4 in. diameter, and 20 ft. in length, so that they
may' be moved through the whole depth of coal in
storage.

Another naval dockyard (fig. 2) has a quay on which
coal storage bins have been erected 30 ft. from the quay-
wall, so that the quay can be also used for other require-
ments than coaling. In this case also the transporter
track is over the bins, but, in addition, cable tracks for
ears of two tons capacity also surmount the bins, for
distributing the coal from the transporter hopper. For
loading railroad wagons or cars, the storage is drawn
from through chutes beneath the bins, but for delivery
from storage to vessels the cable-car track is extended

Fig. 3.—Naval Collier with Mechanical Equipment.

from the top of the bins to ground level by a long sloping
trestle track, the cars being then switched under the
chutes of the bins, and travelling back up the inclined
cable track to the top of the bins again, where they are
discharged into movable and adjustable hopper chutes.
The tower transporter in this case is operated electric-
ally, a grab of two tons capacity being used, which
enables 100 tons an hour to be dealt with. Another
coaling station of somewhat similar arrangement to that
first described has a pier in line with the storage bins
on shore, the elevated cable track which transfers the
coal to storage being 4,000 ft. in length.

It will be observed that all the four equipments in
question, as well as the equipment of the two stations at
the Panama Canal referred to previously, include tower-
type transporters for discharging and ear systems for
transfer to storage. In all four instances, the storage
arrangements comprise elevated covered bins, but at
the Panama Canal the storage for naval requirements is
mostly under water, and the storage for the require-
ments of general shipping is mostly in open stacks,
both of which require the use of movable bridges with
grab cranes or transporters to withdraw from storage,
instead of -gravity discharge through gate valves and
chutes with elevated bunkers.

For the reason previously mentioned, it is not pro-
posed to indicate the situations of the various naval
coaling stations, which, it is perhaps needless to say,
extend beyotfd the coastline of the United States of
America to certain of the oversea possessions of that
nation. Sufficient has doubtless been stated to indicate
the nature of the equipment provided and the import-
ance attached by the United States Government to dis-
tributed storages of coal to meet the needs of a naval
fleet and facilities for handling to and from storage.

In a previous article* of this series, some of the pro-
minent ports concerned with the shipment of American
coal were referred to, and others will be dealt with later.
It is from these ports that the supplies of coal are
shipped to the various naval coaling stations, supplies
by railroad being obtained also in some instances and as
occasion may demand.

Naval Colliers.

Attention may now be directed to mechanically-
equipped naval colliers which provide mobile storage of
coal for bunker supplies to war vessels at sea. Again,
it should be noted that -the United States Navy has also
made greater provision in this respect for its fleet than
any other naval Power; it possesses a considerable
number of naval colliers, those provided in recent years
being of exceptional size, capable of steaming at high
speed and of discharging their cargo rapidly with their
own gear. A brief description of one of these modern
naval colliers will give an idea of the service that can
be rendered by such vessels to a naval fleet at sea; and
when it is mentioned that the fleet of the United States
includes some 75 battleships and cruisers, nearly all of
which are equipped for the use of coal, the importance
of naval coal supplies will be better realised, especially
also if it is called to mind that the German naval raiders

* Colliery Guardian, September 29, 1916.

during the earlier stages of this war were dependent on
coal supplies for their mobility.

One of the latest of these naval colliers (fig. 3) has a
tonnage of about 19,000, with a draught of 27 ft., a
speed of 14 knots, a length of 540 ft., and a beam of
65 ft. This vessel is constructed for carrying oil as well
as coal, and four holds are provided for the former, five
being available for coal, and four which can be utilised
for either oil or coal. The coal holds extend right
across the vessel, are self-trimming, and have an
average capacity of about 2,000 tons each. Two hatches
are provided to each hold, and these hatches measure
32 ft. by 12 ft. 6 in. Three coal bunkers are also pro-
vided for the vessel’s own requirements, the main
bunker having a capacity of about 2,000 tons, whilst
the others are small reserve bunkers with a combined
capacity of about 200 tons. The four holds, which can
be used either for oil or coal cargo, are situated at th?
sides of the vessel, and have a combined coal capacity
of about 1,500 tons.

The coal handling equipment comprises six steel
trestles, each of which supports a pair of derrick booms
on both sides, and two trestles supporting one pair of
derricks each. When these are .rigged outboard for use
they provide a reach of 20 ft. from the side of the
collier, and afford a clearance of 20 ft. above the deck.
Two winches are provided to each pair of derricks, for
operating a travelling trolley on a cable track with a
one-ton grab, one of these winches being used for
traversing, and the other, which has two drums, allow-
ing for the duties of opening, closing, lifting, and lower-
ing the grab. The working of this equipment is effected
by tw’o operators to each
grab, the procedure being
as follows : The double
drum winch is started,
the grab - closing drum
being . put into operation
by means of a clutch; the
other, or holding drum, is
then clutched into gear,
and both drums together
hoist the grab. That par-
ticular winch is then
stopped, the other oper-
ator starting his winch,
and traversing the .grab
on the cable trolley track
over the deck of the
receiving battleship or
cruiser, whereupon the
grab-operating winch is
again brought into use to
open the grab by revers-
ing the clutch of the
opening drum. The tra-
versing winch lever hav-
ing been reversed, this
winch is started again,
and the grab is brought
back to the collier, and
lowered into the hold
by releasing the holding
drum of the grab winch.

The winches are worked by steam, and are of the
twin-cylinder type with friction gears; they are con-
trolled from a platform, above the deck of the collier,
which permits observation of all movements of the grab,
the controlling levers being connected with the winch
clutches and steam valves by spindle shafts and bell
cranks. These winches can also be used, when required,
to work with a skip or a sling for handling bags, instead
of with a grab. It should be noted that, in addition to
the derricks for traverse handling across the collier to a
ship on either side, there is a fore-and-aft rigid girder
trolley track between the three aftermost trestles, which
is used for transferring coal from one of the holds to
the main bunker. The equipment described is capable
of handling 100 tons per hour with each grab, or a total
of 1,000 to 1,200 tons an hour.

Coaling at Sea.

_ Whilst coaling stations serve for supplies at fixed loca-
tions, modern colliers such as described, it will be appre-

ciated, provide mobile supplies and enable a fleet to
remain intact. That means it can maintain its strength,
avoid the necessity of absence and loss of time steaming
to and from a coaling station, which may be some dis-
tance away from a blockade area or course of duty; also,
it avoids the liability of isolated action with the enemy.

The mileage radius of a warship depends, of course,
on a variety of circumstances — size, power, speed,
weather, and capacity of bunkers, etc. A modern
mechanically-equipped collier accompanying a fleet can
replenish the bunkers of three or four ships in a day
with moderate weather conditions. When, however,
such conditions do not exist, other means have to be
resorted to, and we may next consider coaling whilst
steaming in a rough sea, when a collier cannot go along-
side the battleship. In a previous article* the writer
referred generally to the subject of coaling warships,
and the portable equipment which may be carried either
by a collier or the warship itself; and the latest equip-
ment of this description provided on some of the naval
colliers of the United States Navy may now be dealt
with. This equipment comprises a portable cableway,
which may be 800 ft. or 900 ft. in length, and is rigged
between the collier and the warship. The cable, which
forms a track for a travelling trolley, is about 1 in.
diameter, and two hauling ropes are provided, of about
| in. diameter, one of which is attached to one end of the
trolley, and the other to the opposite end. The out-
ward or loaded trolley hauling rope is about twice the
length of the return haul rope, because, of course, it
has to extend from the trolley, when situated on the
collier, to a sheave rigged on the warship, and back to
the hauling winch on the collier. Three special haul-
ing winches are provided, the duty of two of which is
not only to haul the trolley on the cable track to and
from the warship, but to maintain a fairly even tension
on the hauling ropes, whilst the third winch is used
solely to control the tension of the cable track. Th’s
is a special and necessary feature of the equipment, to
ensure satisfactory working, on account of the fluctua-
tion caused by the difference in motion of the collier
and warship, and the ever-varying difference of distance
separating the two vessels. The equipment is completed
by arrangements on the collier and the warship for haul-
ing down the trolley to the deck for loading and delivery
respectively. Coal is delivered from the hold of the
collier by its own gear, and can be.bagged on deck, after
which it is trucked to the cableway loading stage. Loads
of up to 35 cwt. are dealt with on the cableway, five
or six loaded bags being hauled at a time, and the empty
bags are returned by the trolley. An average of 50
loads, or over 85 tons, an hour can be handled by this
system, .and it has been found practicable to rig the
cableway between the collier and battleship in about 20
minutes. (Fig. 4.) The importance of being able to
deliver bunker supplies to a battleship whilst steaming
at a speed of 10 to 12 knots, even in a rough sea, will be
recognised from what has already been stated, and it
may be added that it renders a fleet independent of a
base, or of the necessity for entering a neutral harbour
to coal with .the risk of internment.

In conclusion, the following additional remarks may
be of interest :—Notwithstanding the advantages claimed
for oil as a fuel for marine requirements, the United
States Navy rely almost entirely on coal, only a very

Fig. 4.—U.S. Battleship Coaling at Sea by Cableway.

few of their battleships being equipped for oil only. Coal
bunkering on a battleship is a very different problem to
that of coaling a merchant vessel, as in the former case
the deliveries are mostly effected on deck, and have to
bo transferred on trolleys or bagged by hand labour and
stowed in the bunkers, the position of the latter being
inaccessible for direct deliveries. The storage of the
coal is arranged not only with a view to economy of
space, but also as a protection; and it may be men-
tioned that 2 ft. thickness of coal in a bunker on a
battleship has been found to have resistance to shell
penetration equal to that of 1 in. of iron. A further
advantage of coal in bunkers as a protection is the fact
that, in the event of penetration below the water line,
the inflow of water is reduced, and that circumstance
not only affects the sinka-ge, but also the stability, as it
should be noted that about five-eighths of a stack of
coal is solid, the balance being air space.

* Colliery Guardian, October 2, 1914.