PORT ECONOMICS
a charge of coal in closing. Grabs are of considerable
size: in this country they have a capacity up to 5 tons or
so; in the United States, on the Great Lakes they are
known as Unloaders, and are much larger, running up to
15 or 20 tons capacity.
Oil, being a fluid, is comparatively easily dealt with
by means of a pipe system, with much of the pumping
done by the ship’s own pumps, reinforced, if need be, by a
pumping installation ashore. Flexible armoured hose
pipe connections are required at the waterside to link up
the piping ashore with that on board.
General Cargo. The principal problem in regard to
cargo handling arises with general cargo, on account of its
extreme diversity in size, shape, weight and solidity.
This makes it difficult to handle it by any of the systematic
means employed in the case of bulk cargo. In certain
cases, where a large consignment is fairly homogeneous,
the elevator and conveyor may be utilized with advantage,
say for chests of tea, carcases of mutton, sacks of flour,
etc., but the generality of cargo in a ship’s holds is any-
thing but uniform, and as stevedores usually stack it to
suit the maximum capacity of the hold rather than the
convenience of handling, it comes out in very irregular
fashion—a bundle of canes or of plywood may follow a set
of barrels, or a crate of fruit.
This being the case, reliance has principally to be placed
on appliances which are capable of dealing with a variety
of goods, in whatever order they may present themselves.
And the chief instrument for this purpose, possessing a
remarkable adaptability to all sorts of conditions, is the
Quay Crane, the design of which will receive some little
notice in succeeding paragraphs. It is practically the
only appliance capable of dealing with such unwieldy and
miscellaneous units as bales of cotton and wool, machinery
parts and castings, hogsheads of tobacco, pigs of lead,
ingots of copper and tin, and lumber of varying size.
Some kinds of goods, or their containers, are of a fragile
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