Development of a probabilistic admittance policy for the Flemish harbours
Vantorre, M.; Laforce, E.; Dumont, G.; Wackenier, W. (2002). Development of a probabilistic admittance policy for the Flemish harbours, in: Cox, R.J. (Ed.) Proceedings on CD-ROM of the 30th PIANC-AIPCN Congress, 22-26 September 2002, Sydney, Australia.
Related to:Vantorre, M.; Laforce, E.; Dumont, G.; Wackenier, W. (2002). Development of a probabilistic admittance policy for the Flemish harbours, in: Cox, R.J. (Ed.) 30th PIANC-AIPCN Congress, 22-26 September 2002, Sydney, Australia: book of abstracts. pp. 1299-1313, more
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Document type: Conference paper
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| Authors | | Top |
- Vantorre, M., more
- Laforce, E., more
- Dumont, G.
- Wackenier, W.
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| Abstract |
Deep-draughted ships approaching the harbour of Zeebrugge or the Western Scheldt, the river giving access to the harbours of Antwerp and Ghent, make use of the sea channels Scheur West/East and Pas van het Zand. Due to depth limitations, shipping traffic is subject to tidal windows for drafts exceeding 12.20 m. At present, these tidal windows are determined in such a way that a gross under keel clearance of 15% of the ship's draft is guaranteed. This access policy accounts for water level fluctuations due to tidal action and for the ship's draft, but does not make any distinction regarding other ship characteristics, weather conditions or wave climate.
A potential optimisation of the access policy could consist of the introduction of tidal windows adapted to the actual hydrological and meteorological conditions. For this purpose, among others, a hydro-meteo system was installed by the Division Coastal Waterways of the Waterways and Maritime Affairs Administration in the 1990s, providing the nautical authorities with accurate data about the actual and expected water level and wave climate in the channels.
An optimised access policy requires a reliable estimation of the ships' vertical motions due to their response to the waves and to squat effects, so that the probability of bottom touch during the passage can be assessed. In order to obtain such data, a very comprehensive model test program was carried out by Ghent University in the Towing Tank for Manoeuvres in Shallow Water at Flanders Hydraulics (Antwerp, Belgium).
The test results were collected in a database that can be considered to be unique, not only from the point of view of response of ships in waves in (very) shallow water conditions, but also regarding squat. These data were used to evaluate the reliability and accuracy of two ship motion calculation programs, based on strip theory and on a 3D-panel method, so that missing conditions in the database could be extrapolated.
Based on this database, a calculation procedure was developed, which can be considered as the main tool for establishing a probabilistic admittance policy for the Flemish harbours. |
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