The development and implementation of complex models accurately simulating the performance of advanced tug types continues.

After having focused on different sizes of ASD and VSP tugs for several years, the latest addition is the 80 t BP Rotor Tug ’Geeste’ operated by the German tug operator URAG.  
The Rotor tug concept was developed by the Dutch company Kooren in the late 1990’s and first used to handle the large-windage-area car carriers in the Bremerhaven locks. 

The Rotor tug can be described as a ’conventional’ tractor tug with two azimuth thrusters fore, and the aft skeg replaced by a third azimuth thruster unit. This configuration of propulsion and steering units gives the high-powered Rotor tug extreme manoeuvrability and the ability to work efficiently in narrow spaces. The main new items were the effects of the thruster-thruster and thruster-hull interaction on the force generated by each of the thruster units for this new arrangement of thrusters. This could pose a severe challenge to the naval architect who should build the mathematical models of the vessel. But using DMI’s proprietary DENMark1 modelling system, producing the first version of the Rotor tug model turned out to be fairly straightforward. 

Tug controls

In order to enable the tug master to operate the Rotor tug in the existing tug simulators at FORCE Technology, sets of consoles with the three control handles and the winch control were assembled in-house. These consoles can be connected to any of five interactive tug simulators presently available at FORCE Technology. This flexibility enables simulations to be performed with any combination of up to five tugs of different types, i.e. conventional, ASD, VSP and Rotor tugs. 

Fine tuning of models

The Rotor tug model was first developed under the EU FP6 project EFFORTS and was demonstrated at the concluding conference for that project. This was the first time the Rotor tug simulator was tested by an experienced Kotug Rotor tug master, and already on that occasion, the performance was very close to reality. 

On the advice of the experienced master, some finetuning of the model was done on the spot, and the final model was installed. Subsequently, the Rotor tug simulator has been used on several occasions for navigational studies and for assessment of the performance of different tug types for specific tasks. The portable tug simulator marketed by FORCE Technology is also available in a Rotor tug version, so Rotor tug familiarization training can be performed in the home office of the tug company.