tage that, notwithstanding she was a cargo ship, she would be nearly,
if not quite, as fast as any, save a few of the most recent additions to
the Australian fleet. There is every reason to believe that she has been
driven at 14 knots by about 6,000 horse power. We are inclined to think
that the power has been overstated, and we have it on good authority that
she has more than once attained a speed of 15 knots. Let us assume,
however, that her speed is to be 13 knots, or about fifteen miles an hour.
Assuming the power required to vary as the cube of the speed, if 6,000
horsepower gave 14 knots, then about 4,800 would give 13 knots--say 5,000
horse power. Now, good compound engines of this power ought not to burn
more than 2 lb. per horse per hour, or say 4.5 tons per hour, or 108 tons a
day. Allowing the trip to Australia to take forty days, we have 4,320 tons
of coal--say 5,000 tons for the trip. The Etruria burns about this quantity
in the run to New York and back. For each ton of coal burned in the Great
Eastern about 15,000 tons of cargo and 3,000 passengers could be moved
about 3-1/3 miles. There is, we need hardly say, nothing afloat which can
compare in economy of fuel with this. Taken on another basis, we may
compare her with an ordinary cargo boat. In such a vessel about 3,000 tons
of grain can be moved at 9 knots an hour for 600 horse power--that is 5
tons of cargo per horse power. Reducing the speed of the Great Eastern to 9
knots and about 2,000 horse power, we have 9 tons of cargo moved at 9 knots
per horse power; so that in the relation of coal burned to cargo moved she
would be nearly twice as economical as any other vessel afloat.
The important question is, What would the necessary alterations cost? Much,
of course, would depend on what was done. A very large part of the present
screw engines could be used. For example, the crank shaft, some 2 feet in
diameter, is a splendid job, and no difficulty need be met with in working
in nearly the whole of the present framing. If the engines were only to be
compound, two of the existing cylinders might be left where they are, two
high-pressure cylinders being substituted for the others. If triple
expansion were adopted, then new engines would be wanted, but the present
crank and screw shafts would answer perfectly. The present screw would have
to be removed and one of smaller diameter and less pitch put in its place.
All things considered, we believe that for about
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