According to the passage, a great many factors have to be considered in the design of a ship .

The design of ships is governed by scientific principles
and economic considerations but in practice it has many
of the qualities of an art. The designer may be supplied
with the precise and detailed requirements of an owner
or he may receive only the barest outline of requirements
such as the weight of cargo to be carried and the speed.
The dimensions chosen and the main characteristics of
the ship are governed by the trade in which the vessel is
to compete. High-density cargoes such as iron ore
require little cubic capacity; low-density cargoes such as
bananas require vast cubic capacity. The ports which the
vessel must enter may impose restrictions on length and
draught. Passage through canals may restrict both
draught and breadth. The nature of the cargo may
determine the size of cargo holds and of the hatchways
through which the cargo is loaded and unloaded.
Available facilities at the ports to be entered affect the
loading and unloading apparatus to be installed in the
vessel.