The effect of asymmetry on the ship’s squat when sailing along an approach channel
Delefortrie, G.; Verwilligen, J.; Lataire, E. (2024). The effect of asymmetry on the ship’s squat when sailing along an approach channel, in: Schonees, J.S. (Ed.) Proceedings of the 35TH PIANC WORLD CONGRESS 2024, Cape Town, South Africa, 29 April – 03 May 2024. pp. 710-717
In: Schonees, J.S. (Ed.) (2024). Proceedings of the 35TH PIANC WORLD CONGRESS 2024, Cape Town, South Africa, 29 April – 03 May 2024. PIANC: Brussels. ISBN 978-2-87223-041-9. 1636 pp., more
The running sinkage or squat of a ship is a main contributor to the vertical limitations of a channel and should be duly considered when taking a decision on the required fairway depth for deep drafted vessels. Over the years different empirical formulae have been developed to predict the squat given main ship dimensions, ship speed and the cross sectional area of the fairway under consideration. The PIANC report no. 121 “Harbour Approach Channels Design Guidelines” from 2014 lists a number of them that are advised to be used at design stage. The different formulae have a proven track record of fairly well predicting the magnitude of the squat of a ship sailing along the centreline of a (symmetric) channel with a typical trapezoidal cross section. Nevertheless, none of them considers the effect of asymmetry in the cross section and/or the fact that the ship does not sail along the centreline of a symmetrical cross section. The present paper intends to give an overview of the most important squat parameters, including the effect of asymmetry. A correction is proposed to the existing empirical formulae to deal with the increased squat that occurs when the ship sails asymmetrically along an approach channel.
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