The presence of a mud layer in the port of Delfzijl in the Netherlands implicates a major restriction to the nautical accessibility of the port. At present the maximum drafts for shipping traffic to Delfzijl are limited by a minimum under keel clearance with respect to the top of the mud layer. By means of a simulator study, Flanders Hydraulics Research investigated the influence of sailing at very low and even negative under keel clearances with respect to the mud layer on the inbound and outbound route to and from the port of Delfzijl. In addition, the mud layer characteristics (thickness, density and viscosity) were varied systematically. In order to perform the simulations as realistically as possible, local pilots experienced with the port of Delfzijl, participated in the study.
In 2012 simulations were carried out with a 1700 TEU vessel for which the mathematical manoeuvring models have been derived from comprehensive captive model tests. During this experimental program (2001-2004) the ship behaviour above and in contact with several mud layers was measured. The mud layers were simulated using paraffins characterised by layer thickness, density and viscosity.
The simulator study, ordered by Groningen Seaports and Wiertsema & Partners, revealed the possibility to work with a nautical bottom which is at a lower level than the top of the mud layer. This opens up the possibility for the port of Delfzijl to receive vessels with a larger draft in the future without the requirement of extra dredging efforts.