Mojo Maritime HF4 demonstrates impressive DP performance

Mojo Maritime’s HF4 has demonstrated “stunning” DP (Dynamic Positioning) performance and manoeuvring characteristics based on results of simulations recently undertaken, according to Richard Parkinson, managing Director at Mojo Maritime.

By K.Steiner-Dicks on Sep 8, 2014

Mojo Maritime has concluded the design of the vessel and of the advanced DP system in collaboration with GE and Voith Turbo and has been tested in DP simulations and ship-handling simulators respectively. According to the managing Director, these systems provide an accurate model of vessel DP and handling capability.

The target was to develop a vessel with can hold station to a tight footprint in currents of up to 10 knots- this dramatically exceeds the capabilities of any vessels currently on the market and provides major cost and risk reductions as a result.

“These simulation tools were used to design the DP system for the vessel- this was based on collecting and analysing turbulence data from the Inner Sound, Pentland Firth- the current speeds and directions fluctuate dramatically- these fluctuations are very difficult for existing DP systems to cope with due to the changing variables confusing the software,” said Parkinson.

An extensive list of scenarios has been simulated based on real-life operational situations expected to be encountered, as well as extreme conditions. These scenarios have included failure of a thruster during operation, which is the worst single-point failure expected when operating in harsh environments. The use of computational fluid dynamics (CFD) and tank tests were used to configure and validate the model. Based on the results of the simulations modifications and enhancements were made to the DP control system to improve the performance in high energy tidal sites.

Parkinson said: “The final results of the simulations were very impressive- the vessel demonstrated excellent station keeping at 10 knots even with the effects of the turbulence. The big test was the effect of single point thruster and systems failures- the results were astonishing.”

Toby Bates, DP Training and Development, Mojo Maritime, explained in more detail: “The vessel was able to maintain station even in very extreme environmental conditions- 10kts of currents combined with 50 kts wind and 3m waves. We then failed the thrusters and systems and amazingly the vessel lost a small amount of position and then recovered quickly-- we were astonished that the vessel recovered so quickly in such harsh conditions. ”