New RudderPropeller masters worst-case failure scenario

SRP-D with a propeller shaft featuring an eight-degree tilt.

Navis Engineering Oy, the Finnish manufacturer of dynamic positioning control systems, has endorsed the use of Schottel’s new Dynamic RudderPropeller (SRP-D) system. 

The endorsement came after a joint analysis of the system focused on the mechanical capabilities of the new thruster and how well Navis’ NavDP4000 control system can be adapted to it.

Earlier evaluations of the SRP-D by classification agencies DNV and MARIN “have shown that the effect of its highly dynamic thrust allocation is most evident in harsh weather conditions,” according to Schottel. 

The studies, the Spey, Germany-based company added, “have also revealed that the new thruster significantly improves a vessel’s operational performance. In addition to this, Navis’ latest investigation simulated a Worst-Case Failure (WCF) scenario, examining how well the new thruster can manage such tricky situations.”

Especially for transient processes like the sudden loss of a thruster, “it is essential that the remaining thrust is redistributed as quickly as possible,” said Andrey Loginov, senior DP engineer at Navis. “In the simulated WCF scenario, the fast-response thrusters considerably improved the station-keeping capability and thus the operational safety of the vessel.”

A time-domain simulator was used to complete the joint analysis. Level 3 dynamic simulations of the station-keeping capability for a DPII vessel confirmed that the NavDP4000 control system can use the fast steering-speeds and short ramp-up times of the SRP-D. 

“This proves that a currently available DP control system can instantly produce improved results with the new thruster without any software modification,” said Jan Glas, head of product management at Schottel. 

“It is important that there is real profit at the end of the chain,” he said. “While the physical advantages of the SRP-D are clear, extensive simulations have been conducted to exploit the potential of its use in realistic environmental conditions. But ultimately, we need to be certain that this potential can also be utilized in state-of-the-art DP software.”