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12 st / March 2016 www.sea-technology.com and after the simulation. The cross-sec- tion lines match perfectly, except on the position of the sandbags and the reference sphere. Permanent Port Berth Monitoring Some ports around the world have docks with a lot of business that shoal quickly, typically at entries to bayous. Overestimating the berth depth can cause vessels to get stuck by over- loading or cause arriving overloaded vessels not to be able to dock. Conse- quently, only lightly loaded ships are using these berths and generating di- rect fnancial impact on the ports. In order to reduce this impact, the ports organize periodic multibeam surveys, which provide many uncertainties for the end users. In addition, the survey work causes even more pressure on the ports' budgets, so the number of these operations must be reduced to an accepted risk level. For example, the Port of Houston publication "Best Prac- tices for Berthing Area Surveys" states: "Terminal operators must decide the level of risk they are willing to accept when deciding whether or not to survey and with what method the data will be collected." There are many challenges for ports that infuence the ac- curacy of the latest berth depth information, including: dredg- ing operations, scour detec- tion and monitoring, sediment buildup, periodical bathymetric surveys, bridge and pier inspec- tions, and post-storm response and recovery. Users and authorities know that due to natural or artifcial process- es, the berth depth changes over time. Having access to marine charts (ENC), users receive information only for the published maximum safe draft, and they don't have access to berth survey data. Moreover, in order to increase safety, the authorities must apply a fac- tor of safety to account for condition changes. This factor of safety increases over time and it is subjective, not ob- jective. Errors and losses occur due to overconfdence or excessive risk miti- gation. A classic example is the Port of Houston. More than 70 percent of the vessels carry hazardous materials, forc- ing the vessel operators to individually increase the factor of safety even more than the given uncertainty factor by the port authorities in the ENCs. For the Port of Houston, to name just one example, extending the structural monitoring application capability for the K-Observer system to permanent monitoring of port berths would pro- vide a cost-effective solution for real- time depth measurements. The system is able to record berth condition prior to a ship arrival and after a ship depar- ture. The real-time depth information would be available for the users, mak- ing them more secure in their decision making during operations. Additional- ly, the port would have information on any scouring on the foundations of the quay walls caused by vessel thrusters. Having accurate volume difference in- formation (before and after), the port could charge the vessels proportional- ly for some of the costs of remediation. K-Observer provides real-time depth measurements and tide and SV correction. The benefts are increased vessel safety, bigger vessels able to ap- proach the berth, real-time measure- The difference grid showed a deviation of around 0.35 m on the position of the reference sphere and 0.2-m deviation on the position of the sandbags.