Page 75 - Practical Ship Design

46 Chapter 2

2.6.4 Landing craft and logistic support ships
The unusual feature of these ships is their beaching role. This requires the staff
requirements to specify the deadweight that the ship has to be able to land on an
open beach, as well as the greater deadweight that the ship should be able to carry
in a transport role. This in turn requires a statement on the wading ability of the
vehicles which may be landed, defining the maximum permissible forward draft,
and a statement on the gradient of the beach, defining the draft aft.

2.6.5 Landing ship docks

The distinctive feature of these vessels is the dock incorporated in their stern
section. The length and breadth of this must suit the number and dimensions of
craft that are to be carried in it or use it. The L.S.D. must be able to be trimmed to
provide the necessary depth of water in the dock to suit the draft of the user craft
and the change of trim from the seagoing condition must be to a rapid timescale
against the probability that enemy action is likely to be imminent.

2.6.7 Fuel and stores replenishment ships
The distinctive feature of these ships is the provision of rigs designed to achieve
the transfer of stores or fuel, or both to warships at sea and the number and types of
rig must be specified.
Until fairly recently, liquids were carried in fleet tankers and dry cargoes in fleet
store ships. For a ship requiring both liquids and solids this meant two storing
periods so the advent of a new ship type (AOR) which could provide both on a “one
stop” basis was a major improvement. The staff requirements for such a ship have
to take account of the fact that this is becoming an exceedingly valuable ship and
needs a good self-defence capability.

2.7 ADVANCED MARINE VEHICLES

The first section of this chapter advocated that design objectives should be stated in
broad terms and should demand the most desirable qualities. Although there is
little point in setting objectives that cannot be achieved, the possible area of
achievement can be greatly extended if the whole range of marine vehicles can be
considered as contenders, although it must be said that the transport efficiencies of
most of the alternatives to displacement ships are much lower than can be obtained
from a conventional ship. Figure 2.1, abstracted from Eames 1980 RINA paper
“Advances in Naval Architecture for Future Surface Warships”, gives an approxi-
mate indication of where, in terms of speed as measured by volumetric Froude
number, the use of these vessels is worth considering.