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Encounters in Restricted Waters

Published online by Cambridge University Press:  23 November 2009

T. G. Coldwell
Affiliation:
(Humberside College of Higher Education)

Extract

Lewison gave a brief outline in modelling of marine traffic flow and gave four possible definitions of the ship to ship encounter as well as developing his own optimal criteria. Barratt has been working on the concept of an encounter for several years and has developed the postulates given by Stratton in a presidential address to the Royal Institute of Navigation in 1971. It is interesting to note that Lewison1 distinguished between a ‘ship domain’, which is the area around a vessel that it is observed to keep free of other traffic and is estimated in terms of the actual density of shipping observed to occur around a vessel, and an ‘encounter area’, which is a radius traced out around a ship in the different directions from which threats may come and is the desired area which the vessel should try to keep clear. The nicety of the ‘encounter area’ is that it is generated in terms of mathematical models and in quantitative terms, and can be reasonably easily established; but it totally ignores any human element or navigators' preferences, whereas the ship domain takes both these factors into account and can only be established after long observation of actual traffic behaviour.

Type
Research Article
Copyright
Copyright © The Royal Institute of Navigation 1984

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References

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