Scientific American Supplement, No. 561, October 2, 1886Various
Science
Scientific American Supplement, No. 561, October 2, 1886
Various
Science -- Periodicals
Mr. Biles remarked that there were many advantages in the use of twin
screws which had not been sufficiently taken into account. When a ship
with twin screws was being handled in dock there was greater
maneuvering power, and therefore less liability for the ship to come
in contact with the walls, although, if she did so, there would be
greater probability of damage to the propellers. He thought means
could be easily devised of protecting the screws when the ship was in
dock. Another of the incidental advantages connected with twin screws
was that smaller engines and smaller propellers were required, and
therefore they might run them at a higher speed. They would also get
lighter machinery with twin screws, and there would be less liability
to have bad castings and forgings in the smaller engines, and of
course the cost would be less.
With respect to the question of the middle line bulkheads, he could
not quite agree with Mr. John as to the great advantages of them in a
big passenger steamer. He thought there would be greater difficulty in
managing a ship so built if she was in danger of sinking. Increased
subdivision in a longitudinal direction was a very desirable thing,
and almost necessary for a condition of immunity from sinking. In
future Atlantic steamers longitudinal bulkheads should be placed not
in the middle line, but nearer the sides of the ships, and they should
recognize the fact that they had engines and boilers in different
compartments, and make arrangements whereby the ship would still
float, although the doors in these compartments were kept open. The
proper way to arrive at that was to have a ship with great beam, and
to have two longitudinal bulkheads at considerable distances from the
sides of the ship, subdivided as completely as possible, both under
and above water, so that, even supposing they got water into the space
between one bulkhead and the side of the ship, they would have
sufficient buoyancy in the other parts of the ship to keep her afloat.
Broad ships must necessarily mean deep ships, in order to have comfort
at sea. They were limited in length, and first came the question how
many passengers they wanted to carry. The experience of a ship like
the America--which was only 400 ft. in length--showed it was not
necessary to go to great length to have great speed. A ship of 400 ft.
to 430 ft. in length, 65 ft. of beam, and with a depth of 45 ft.,
would be a ship of proper dimensions for the Atlantic trade, and he
believed it quite possible to build a vessel of special construction
of about 7,000 tons gross register which should steam with less
consumption of coal than the Umbria and Etruria at a rate of 22 knots,
crossing the Atlantic from Liverpool to New York in six days. He
thought that was likely to be the vessel of the future, and that it
would be quite as commercially successful as the Umbria or Etruria.
Public-domain text, read in full here on John Shaqi.
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