Norwegian Bliss after turning at Emden, reality vs simulation

forces act directly on the vessel and without delay.

interaction between the ship’s hull, pods or propeller/rudder configuration and riverbanks is playing an increasingly important role. As well as this, the available space for the assisting tugs decreases, therefore tugs towing on a line are not efficient anymore, especially when transiting bends. Working in close co- operation MARIN, Meyer Werft and the EMS Pilot Association have found solutions for both challenges.

To reduce hydrodynamic interaction, the sailing speed had to be reduced and pod use had to be optimised. This was only possible by introducing a semi-rigid way for tug assistance. By fixing a tug to a pontoon at the bow of the vessel and a tug to the stern of the vessel, the required space reduces dramatically and the tug

In this way the motions of the vessel can be controlled in the confined river channel much more accurately. Manoeuvring tasks and compensating wind forces are divided over the two tugs, the pods and bow thrusters. Splitting up these tasks makes it easier for the pilots to control the vessel. As three pilots sail the vessel, coordination of these separate tasks is of the utmost importance for a safe conveyance.

Optimum manoeuvring strategies During several research projects carried out for planned new vessels being built at Meyer Werft, optimum manoeuvring strategies and sailing speed scenarios have been developed in close co-operation between MARIN and the EMS Pilots involved. The first part of the conveyance - lining up the vessel in front of the lock, passing through the lock to enter the river and navigating the first river bend - are particularly challenging. To accommodate the safe lining up of the cruise ship and passing through the lock, five rolling fenders have

been placed along the eastern lock wall and one rolling fender at the west side of the entrance. During this stage the speed of the vessel is kept very low (0.1 to 0.2 kts) to avoid heavy impacts when landing on the fenders. The speed when navigating the lock is also kept very low to minimise a potential ‘blockage’ as the margins between the vessel’s hull and fenders are not more than 1 metre on each side.

In addition to the research and training for regular activities, emergency situations have also been studied and training scenarios have been developed for these events. Due to the separation of the tasks it is easy to analyse the effects of a malfunction of a pod, bow thruster or one of the two tugs. Recently, the possibilities of executing the conveyance with one pod out of order have been studied. The wind limits and duration of the total conveyance with one pod out of action were determined. Research and training in virtual reality using simulators optimises the vessel’s manoeuvres and improves safety and efficiency, especially when manoeuvring margins become extremely tight.

report 19

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