NAABSA (not always afloat but safely aground) berths are those where ships sit on the riverbed or seabed at low tide rather than staying afloat. The practice is common in ports with high tidal ranges, but there is a real risk to ships if the bed of the berth pocket is in any way obstructed or uneven. 

To avoid major liability claims for hull damage and subsequent disruption to port operations, port authorities need to ensure their NAABSA berths are regularly surveyed, dredged and levelled. In addition, all dropped cargo incidents need to be investigated and resolved without delay.