Feature 5 | Survivability
visualisation of missile on the County class destroyer
the spread of ex-HMS Devonshire caused blast
fragmentation. overpressure through several decks and
several longitudinal subdivisions. The
SURVIVE prediction of overall spread
is very accurate, as is the actual level
of structural damage caused (not
shown here).
Case study –type 45 destroyer
One common misconception is that
assessment of whole-ship survivability
once a design starts to mature is too slow a
process to actually influence the developing
design, and that data requirements are
too onerous to allow sufficient detail
to be considered. Experience suggests
between ship states or diagnosing and after a given time. otherwise.
recovering from fires, floods and damage. The SURVIVE team was involved
iterative improvements with the Type 45 destroyer programme
reaction to damage At any stage of design assessment, two throughout the design process, performing
Part of the scenario defined for a questions are important: has the design a number of iterations of analysis,
recoverability simulation is the command met the requirements placed upon it; and, identifying weak points, evaluating change
aim that must be maintained. This is how can the survivability of the design be options and suggesting improvements at
represented by one of the ship’s functional improved? Through an iterative process each stage.
systems at any specific time. For example, SURVIVE can answer both questions and Vulnerabilities to single attacks were
the command aim might be to undertake prove whether the chosen design changes identified and mitigated or eliminated.
air operations for two hours, followed by are having a positive effect. As illustrated SURVIVE’s multi-strike ability was used to
the need to maintain full propulsion for a in the Type 45 case study below, the simulate multiple incoming threats leaving
further two hours. assessment can be rapid enough to keep a platform able to keep fighting after
At each time step SURVIVE works pace with a changing design. one or more hits. Casualty assessments
out a strategy to maintain the command One measure frequently taken to try were performed to establish the level of
aim, encompassing damage control to improve a ship’s performance is to protection afforded to crew. Magazine
and fire fighting activities, the reduce the spread of damage through the safety case assessments have informed the
reconfiguration of distribution systems introduction of blast resistant structure. protection of magazines, both in terms of
and the repair or replacement of damaged The aim of any measure is to reduce the the effect of incoming threat weapons and
equipment. These activities are all damage footprint of a particular system the sympathetic detonation of the ship’s
dependent on the management of the of interest. It may be that a number of own munitions.
available crew and resources. different options are identified that all Examples of the influence of SURVIVE
A typical simulation time for a single contribute to a drop in vulnerability. In in the design of Type 45 include: armour
threat exhibiting the main primary damage this case SURVIVE results can be used to to protect functional as well as magazine
mechanisms is a handful of seconds trade off the options for improvement to spaces; sacrificial compartments that
or less, making very large numbers of inform the design team of a suitable way protect more critical spaces; survivable
repetitions commonplace. Numerical ahead given cost and risk. distribution layouts and principals,
results are averaged for each item of such as the absence of a dedicated
equipment or functional system to give validation (and therefore critical) conversion
an overall probability of escaping damage. SURVIVE benefits from many years of machinery room; blast resistant structure
The binary nature of system availability small- and large-scale trials conducted by on key boundaries; redundancy of
through time (a system is either available the UK and international partners, as well command and communications assets;
or not, although degraded capabilities as data coming from wartime incidents. identification of excessive redundancy in
can be included as separate systems) These combine to establish the accuracy the internal network systems, leading to a
becomes probabilistic with the chance of and credibility of SURVIVE’s structural simplification of the design and hence to
availability at a given instance post-hit and functional damage prediction real cost savings. WT
being available. This output can be used as algorithms.
comparison to a quantified recoverability One example of the accurate prediction * This article is an edited version of a paper
metric – that a given function should of blast spread is shown in the figure. A prepared for Warship Technology by James
have a minimum probability of availability high-seas firing strike from a Sea Eagle Schofield MIMA MRINA, QinetiQ Rosyth.
32 Warship Technology March 2010
WT_Mar-2010_p30-31-32.indd 32 23/02/2010 16:01:14
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