Page 74 - Practical Ship Design

Setting Design Requirements 45

disabling it; if on the other hand he cannot detect it but you know where he is, you
are well on the way to winning. On the other hand, detection equipment is
constantly improving so maybe today’s expensive low signature ship will be as
readily detected in the future as today’s cheaper one so there is undoubtedly an
argument for more ships.
Measures to minimise signatures of all types - underwater noise, airborne
noise, infra-red, radar, magnetic, etc. - are very important staff requirements for
most types of warship. The importance of the various signatures varies with the
vessel’s primary role, with seaborne noise being most important for submarines
and anti-submarine frigates and the magnetic signature being so vital for a mine
hunter that the whole construction of these ships is of non-magnetic materials.
The principal requirements of a warship are the combat systems with which the
ship is to be fitted, i.e. the guns, missile systems, helicopters and/or aircraft plus the
whole range of accompanying command and control systems. Backing up the
offensive weapons are a range of self-defence weapons: anti-missile missiles and
guns, chaff launchers, etc.
The next most important requirement is the operational service speed and in
particular the speed that can be maintained in adverse weather. Another speed that
must be specified is the economical cruising speed, which is often only about half
the service speed.
The endurance of a warship is generally stated in terms of distance or of the
number of days that can be spent at the economical speed plus a shorter distance or
time at the maximum service speed. The endurance of most warships is low by
merchant ship standards, reflecting the cost of providing space and deadweight in a
warship and the availability of replenishment at sea which navies provide as a
corollary.
Replenishment at sea can also supply replacement stores and ammunition,
reducing the quantity that must be carried.
The requirements for shock and vulnerability are two important standards
which must be specified for a warship.

2.6.3 Naval auxiliary vessels - general

The requirements for these vessels tend to combine most of those discussed under
warships with others mentioned in the section on merchant ships. However, a few
naval auxiliary types bring their own special problems. It is worth commenting that
in the British Navy some of the ship types discussed in this section are naval
manned and can therefore in some respects be regarded as warships, others are
merchant seaman manned and a third category has both naval and merchant
manning.