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guiding ships through the existing IJmuiden North Lock (Noordersluis)? The model ship used by Deltares for testing purposes was considerably larger than the ships currently passing through the North Lock. This makes it difficult for pilots to accurately apply the research results
to their daily practice. One issue in that respect is that the actual measured values when passing the North Lock are not known. At present, the pilots assess the forces arising from the lock exchange currents themselves based on feeling and experience and ensure that they release the mooring lines on time.
As part of his thesis in the Master in Maritime Piloting programme, pilot Allert Schotman has focused on this knowledge gap. His research meets the need of pilots for more insight into the forces that are present in the New Sea Lock and the manner in which these will affect the present generation of ships; of course, the manner in which this relates to the forces they are currently experiencing in the North Lock is also important. Which factors are relevant here? The study also enables research institutes to compare the findings of their scale models and calculations against daily practice.
MEASUREMENT IS KEY
In collaboration with Deltares and Rijkswaterstaat (the executive agency of the Ministry of Infrastructure and Water Management), Schotman took measurements in the scale model of the New Sea Lock again in 2017. This time a smaller ship, comparable to the largest type of vessel (Aframax) currently navigating the North Lock was used. The transversal and longitudinal forces for both an inbound and an outbound ship were measured. Various draughts were also tested, as was the effect of having two outbound vessels moored behind one another in the lock. In the North Lock itself, full-size measurements with the same ship type were performed on outbound ships to determine the magnitude of
the occurring longitudinal force. Measurements into the longitudinal forces that occur at different draughts were also carried out using three smaller ship types.
UP TO 30 PERCENT GREATER FORCES
One of the most important conclusions from the comparison between the scale model tests and the field tests is that for the same ship,
the outbound longitudinal force in the New Sea Lock increases by
a maximum of approximately one third (30 percent) compared to
the North Lock. As soon as the New Sea Lock comes into use, pilots consequently need to exercise an even greater degree of caution than is currently already the case for the North Lock. This knowledge is essential in order to be optimally prepared.
Follow-up studies are still ongoing. The results are not only important for the Amsterdam-IJmond region; they could also prove highly valuable for the new sea lock that is currently under construction in Terneuzen in the southwest of the Netherlands and for locks elsewhere in the world, such as the ones in Panama.
TEST WITH STRONGEST TUGBOAT
For testing purposes, pilot Allert Schotman suspended the strongest
port tugboat in the Netherlands, Brent, behind an outbound Aframax vessel. Brent was instructed to keep the ship in position after the mooring lines had been cast off. That took quite some effort; forces up to 65 tonnes were measured.
OUTCOME OF HBO MASTER’S DEGREE
Six years ago, the Dutch training course for registered pilot became an advanced higher vocational programme (HBO in Dutch) leading up to a Master’s degree. A new dimension in this Master in Maritime Piloting degree is that aspiring pilots are expected to independently research a topic that is relevant to the daily practice of pilotage and that they share their findings by means of a paper and a presentation. Various experienced pilots associated with the course have also completed the HBO master’s degree. Pilot Allert Schotman from the Amsterdam-IJmond region conducted the research into the occurrence of hydrodynamic forces in locks in this context.
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