FT. IN.
Length extreme. 262 6.40
Length at load-line. 234 0.94
Beam. 53 8.38
Height between decks. 6 8.72
Height of lower port sill. 7 2.63
Depth of hold. 26 9.34
Deep-load draft. 25 3
Immersed cross section, sq. ft. 1063.48
Displacement. tons. 6050
Diameter of cylinders. 8 2.45
Length of stroke. 5 3.06
Diameter of propeller. (4 bladed) 19 0.70
Pitch " " mean) 37 11
She has eight boilers, each having five furnaces, consuming, at full
speed, (12.14 knots,) 143 tons of coal per day, for which she stows five
days' supply. The boilers and engines occupy eighty-two feet in the
length of the ship.
The trial of this ship has established the practicability of adapting a
propeller to a ship of the largest class, so as to insure great speed,
and constitute a most effective man-of-war for certain purposes and
in certain situations; but when the great weight of the engines is
considered, and the large space they occupy in the vessel,--thereby
diminishing the stowage of supplies,--and further, that, after the coal
is exhausted, the ninety-gun ship has but the sail of a sixty-gun ship
to rely upon, it is not easy to avoid the conclusion, that, however
useful such a vessel may be for short passages,[1] and in those seas in
which her supplies of coal and provisions may be constantly replenished,
her sphere of action must be very limited, and she could not be relied
upon for the long cruises and various services on which an ordinary
line-of-battle ship is employed.
[Footnote 1: For debarking a regiment or two of Zouaves on the shores of
the Adriatic or upon the coast of Ireland.]
A ship constructed on the plan of the Napoléon, for the sake of gaining
a speed of twelve knots per hour for the distance of about two thousand
two hundred miles, is compelled to sacrifice a great part of her
efficiency in several most important particulars.
In time of war, at short distances from port, for the defence of bays or
harbors or the Florida channel, for the speedy transport of troops to an
adjacent coast, or to force a blockade, such a vessel would undoubtedly
be a most valuable addition to our navy: but her employment must
necessarily be confined to such circumstances and such situations; for
should she unluckily fall in with an enemy's squadron, with her coal
expended, or her machinery rendered useless by any of the numerous
accidents to which steam-machinery is so constantly exposed, with her
comparatively light rig, and want of stability in consequence of losing
so great a weight of coals, she would hardly prove a very formidable
opponent.
Therefore, while admitting the importance and necessity of providing
for special service a small class of fast, full-power steamers, it is
submitted that the auxiliary screw-steamer is the description of ship to
which the largest and best consideration should be devoted; for to the
nation possessing the most efficient fleet of such vessels must belong
the dominion of the sea. And while their cost is counted, let it at the
same time be remembered that their value can be estimated only by the
character of the service they may render, and that their capacity for
aggression abroad makes them the best defence at home.
Having briefly referred to the various views entertained in regard to
the steam-power with which the navy should be furnished, it will be
seen that a difference of opinion on this important subject may most
reasonably be entertained.
None can doubt the advantages of celerity to a man-of-war, yet many
believe it would be too dearly purchased by the sacrifice of space to
such an extent as would require supplies to be often replenished; as
this necessity would in war confine the operations of the navy to our
own shores.
On the other hand, it is admitted, that, without high speed, a ship of
war cannot exercise many of her most important functions,--that she can
neither choose an engagement, protect a convoy, nor enforce a blockade.
The best experience affirms the policy of giving to our cruisers as
large steampower as is consistent with a due development of all other
warlike qualities; for what would avail the superior armament of a ship,
if the option of fighting or flying remain with her adversary, which
must be the case when the latter commands higher speed? The introduction
of improved ordnance, throwing heavy shells with great precision at
long ranges, gives increased importance to celerity; for in any future
fleet-fight, victory should belong to that flag having at command a
steam-squadron of superior speed, which may thereby be concentrated upon
any point without having been long under fire.
May not the command of a maximum speed of thirteen knots be obtained
from the machinery now employed for a maximum speed of ten knots? It
evidently may, and with great economy, too, by the simple introduction
of artificial draft, and the use of steam of higher pressure, when
requiring the highest speed. At present, in our men-of-war, the boilers
are proportioned for natural draft, burning about twelve pounds of coal
per square foot of grate per hour, and for a steam-pressure of fifteen
pounds per square inch. If, then, the boilers be proportioned to burn at
the maximum, with blowers, say twenty-two pounds of coal to the square
foot of grate, and to generate steam of forty pounds to the square inch,
we shall double the power developed by the machinery, and consequently
derive from it the same speed that could be attained without blowers
from double the machinery; while the natural draft and the usual
pressure of fifteen pounds would give sufficient speed for ordinary
service. The inconvenience of the higher pressure with blowers could
well be endured for the short and occasional periods during which they
would be required.
To create a perfect screw-frigate, a ship with sail-power complete, and
efficient for any service that may be required, the endeavor should be
made--by getting rid of every dispensable article of weight or bulk, and
without reducing supplies below three months' provisions and six weeks'
water--to find space and displacement for an engine of sufficient force
to drive her thirteen knots an hour, together with at least ten
days' full consumption of fuel; and this, it is believed, might be
successfully accomplished in ships of the dimensions of the Wabash,
beginning with a judicious reduction of spare spars, spare sails, and
spare gear, and by the addition of blowers to their present machinery: a
subject which should immediately receive the earnest consideration of a
commission of the most intelligent officers.
Having fixed upon the proportions of hull and spars, the form of
propeller, and the plan of engine, a cautious discrimination should be
exercised in multiplying the types of either. Besides economy, many
other advantages would flow from a judicious regard to similarity in
build; as it would permit us to relieve our ships of many of the spare
spars with which they are incumbered, and we should probably not again
hear of suspending the operations of a frigate thousands of miles away,
until a crank or rod could be sent to her; because, when ships of the
same class are cruising together, by a careful distribution of spare
spars and machinery among them, it is hardly probable that damage would
be sustained, or loss of spars or "break down" occur, which might not be
remedied by the resources of the squadron.
On the other hand, this system not be carried to a Chinese extreme, lest
we follow too long a false direction,--thus losing the advantage of
improvements constantly being made. For such is the change in all things
pertaining to maritime war, that neither model of hull, plan of engine,
nor mould of ordnance is best, unless of the latest creation. True
progress will be most judiciously sought in not departing too suddenly
and widely from the established order.