Exploring tug performance with the Svitzer Deben
A team from Damen Research & Development recently had the opportunity to gather valuable performance data from the Damen ASD 3212 tug Svitzer Deben operating in the Port of Felixstowe in the UK.
This came about a year after her delivery, because the team was aware that the Svitzer Deben was being operated in the so-called powered indirect mode on a daily basis since delivery.
This type of manoeuvre is rarely used on a daily basis, and so Damen R&D was eager to study its repeated use on this particular design. Its regular use in daily operations would allow the team to measure multiple escorting operations over just a few days.
During the design stage of the ASD Tug 3212, Damen R&D had focused extensively on escorting performance using scale models and software to assess the seakeeping characteristics and escorting performance, both in calm water and in waves. However, the opportunity to conduct full scale tests and gather anecdotal feedback from the master and crew would be invaluable in gaining additional insights into operations in the real world.
A team of five Damen experts plus their measurement and camera equipment spent 2 days on board the Svitzer Deben, measuring and recording speed, drift, heel angle, camera footage and tow line forces, together with the propulsion settings. Six different ship handling operations were assessed, some involving the very largest container ships. The data collected has since delivered valuable new insights into the forces generated at different speeds during real life operations, and these have been compared to the earlier data from the simulations and model tests. The results showed that the steering forces in indirect towing mode were as high as expected and the tug was very stable when heeling into the line. While this exercise will not result in any immediate design changes, the process of continuous validation and improvements to the simulation programme will benefit future tug designs.