Page 184 - Practical Ship Design

150 Chapter 5

Towards the end of the decade (in 1987) the firm of consultants YARD (now
BAeSEMA) for whom the author worked at that time came to the conclusion that it
was likely that in the not too distant future there would be a need, for demographic
reasons, for very much reduced crews. After considerable study into ways of
reducing manpower, they found that a combination of changes in operational
procedures and the introduction of new equipment for which the technology
already existed or would shortly be available would make it possible to reduce the
crew of a frigate to 50 men. They then went on to develop the design discussed in
Chapter 16 to prove their case. Whilst this design was a look into the future and
needs the full development of equipment then still only at the prototype stage it
was, somewhat to the firm’s surprise, warmly welcomed by naval staff from
several navies, as showing the way ahead.
With these major changes in crew numbers over a short period of time, it would
be wrong to try to give any more detailed guidance on warship crew numbers.

5.6 DESIGNS BASED ON DECK AREA

Prominent amongst ships designed on the basis of deck area are train and vehicle
ferries. If the space for trains and vehicles is enclosed it can of course be argued
that these are volume designs, but this is not strictly true as the volume required for
these must be provided on a limited number of decks, generally one or two. These
decks must be above the bulkhead deck and have free access to the loading/
unloading doors and/or ramps, making the case for considering them as area
designs. Figure 5.3 extracted from a paper by Alan Friis to the Cruise and Ferry 91
Conference shows a typical deck view and midship section of a Danish combined
train and vehicle ferry.
In laying out the deck of train ferries it is essential to have good guidance on the
minimum acceptable turning radius and on the necessary clearance between the
tracks that is associated with this.
For the easier case of road vehicles, the clearances allowed must enable drivers
and passengers to use car doors without too much difficulty. This occasional and
not particularly fat passenger thinks that these clearances are too frequently
skimped and is reminded of the advice he was given as a young man “Go and try it
yourself and see what space you need”.

5.7 DESIGNS BASED ON LINEAR DIMENSIONS

There are a number of ship types in which the design process proceeds directly
from the linear dimensions of the cargo, an item or a number of items of equip-
ment, or from constrictions set by canals, ports, etc. and for which the deadweight,