Page 26 - Navigator 19

The model ship used by Deltares for testing purposes was considerably larger than the ships currently passing through the North Lock.
RESEARCH UNIQUELY LINKS THEORY AND PRACTICE
Ready
FOR THE LARGE HYDRODYNAMIC FORCES IN NEW SEA LOCK
IN MANY SEA LOCKS, SHIPPING TRAFFIC IS CONFRONTED WITH THE DIFFERENCE IN DENSITY BETWEEN FRESH WATER AND SALT WATER. THIS CREATES STRATIFIED FLOWS IN THE LOCK CHAMBER THAT CAN EXERT GREAT HYDRODYNAMIC FORCES ON SHIPS MOORED IN THE LOCK. IN IJMUIDEN, WORK IS CURRENTLY IN FULL SWING ON THE CONSTRUCTION OF THE LARGEST SEA LOCK IN THE WORLD, WHICH WILL MEASURE 500 X 70 METRES. WHAT IMPACT DOES THIS VAST SIZE HAVE ON THE HYDRODYNAMIC FORCES GENERATED BY THE LOCK EXCHANGE CURRENT?
At research institute Deltares in the Dutch town of Delft, a scale model of the New Sea Lock has been constructed to perform tests with a model ship representing the maximum size of vessels that may possibly pass through the lock in the future. During these tests, very large forces of up to 130 tonnes were measured after the lock gate had been opened, particularly during the lock exchange flow (Mind you: the strongest port tug boat is capable of pulling around 70 tonnes).
This represents a major challenge for the pilots of the Amsterdam- IJmond region of the Dutch Maritime Pilots’ Organisation who will soon be guiding sea-going vessels through the new lock. Given the larger dimensions of the New Sea Lock, they are concerned that
the ships might be exposed to hydrodynamic forces so strong that dangerous situations might arise: from mooring lines snapping to ships colliding. This mainly concerns the longitudinal force on outbound vessels (heading towards the sea), when the vessels are forced out
of the lock by the current, and the transversal force on the bow of inbound vessels (headed towards Amsterdam) when the current enters the lock.
GAINING MORE KNOWLEDGE
How does this differ from the current daily practice of the pilots when
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