All harbours require frequent dredging to cope with sedimentation. In certain cases the deposited sediment/silt forms a weak soil layer referred to as fluid mud. The top layer is often used as nautical bottom, while its presence is not necessarily harmful to the vessel. This could lead to the conclusion that the safety margin underneath a vessel (i.e., Under Keel Clearance (UKC)) is too large/safe and can be reduced. Research indicates that the UKC can be decreased to smaller (