Depending on the configuration of pier, water could help dissipate part of berthing energy. For instance, for closed docks in which there is a solid wall going down directly to the bottom of seabed, the quay wall will push back all the water that is being moved by the vessel and creates a cushion effect which dissipates part of berthing energy (10-20%). On the contrary, for open dock in with piles beneath and water can flow through the underside of piers, there shall be no cushion effect of water.
Similarly, the larger is the draft of vessels, the less trapped water can escape under the vessel so that the cushion effect of water can be enhanced to dissipate part of berthing energy.
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This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.
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