Page 330 - Introduction to Naval Architecture

SHIP DESIGN 315

usually be produced showing the trade-offs between various conflicting
requirements or to highlight features that are unduly costly to achieve
and rnay not be vital to the function of the ship.

Contract design
Once the owner has agreed to the general size and character of the ship
more detailed designing can go on. The contract design, as its name
implies, is produced to a level that it can be used to order the ship from
a shipbuilder, or for a contract price to be quoted. At this stage all
major features of the ship will be fixed. Usually some model testing will
have been carried out to confirm the main performance parameters.
Layout drawings will have been produced to confirm spaces allocated
to various functions are adequate. The power and type of machinery
will have been decided and the electrical power, chilled water, air
conditioning, hydraulic and compressed air system capacities defined.
The basic ship design drawings will be supported by a mass of
supporting specifications which will control the development of the
final design.

Full design
The detailing of the design can now proceed leading to the drawings,
or with computerized production systems, computer tapes, which are
needed by the production department to build the ship. Included in
this documentaion will be the detailed specification of tests to be
carried out including an inclining experiment to check stability and the
sea trials needed to show that the ship meets the conditions of contract
and the owner's stated requirements. These are not necessarily the
same. For instance, for warships contractor's sea trials are carried out to
establish that the contract has been met. Then, after acceptance, the
Ministry of Defence carries out further trials on weapon and ship
performance in typical sea-going conditions.
Also specified will be the shipyard tests needed to be carried out as
fabrication proceeds. Thus the testing of structure to ensure watertight
and structural integrity will be defined. Tests of pipe systems will lay
down the test fluid and the pressures to be used, the time they are to be
held and any permissible leakage.
Then there is the mass of documentation produced to define the
ship for the user and maintainers. There are lists of spares and many
handbooks. Much of this data is carried in micro-form on the ship to
facilitate usage and to save weight and space.

The impact of computers
Computers have made a great impact upon the design, production and
12
operation of ships. That impact is felt in a number of ways: