Mojo Maritime’s HF4 demonstrates stunning Dynamic Positioning performance and manoeuvring characteristics
Mojo Maritime’s HF4 has demonstrated stunning DP (Dynamic Positioning) performance and manoeuvring characteristics based on results of simulations recently undertaken, the company said in its press release. Mojo Maritime has concluded the design of the advanced DP system in collaboration with GE and Voith Turbo and it has been tested in DP simulations and ship-handling simulators respectively. These systems provide an accurate model of vessel DP and handling capability. The target was to develop a vessel with the ability to 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, thereby providing major risk and cost reductions across a range of industries and operations.
The simulation tools used to design the DP system for the HF4 were based on collecting and analysing turbulence data from the Inner Sound, Pentland Firth. The current speeds and directions at this site fluctuate dramatically, making them very difficult for existing DP systems to cope with due to the changing variables, thereby confusing the DP software.
An extensive list of scenarios has been simulated based on a wide range of real-life operational and worst case situations. These scenarios have included failure of a thruster during operation, which is the worst single-point failure expected when operating in harsh environments.
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:
Quote from Toby Bates, DP Training and Development, Mojo Maritime:
“The vessel was able to maintain station even in very extreme environmental conditions- 10 knots of currents combined with 50 knot winds and 3m waves. We then failed the thrusters and systems and amazingly the vessel lost a small amount of position yet recovered within seconds.”
This extraordinary DP performance has the potential to deliver techno-economic advantages to a range of applications in the renewable energy sector- notably:
Tidal energy – where the vessel will have the capability to operate through neap and spring tides in even the most aggressive sites such as The Pentland Firth and Raz Blanchard. This has a major impact on operability and ultimately installation costs and production. Additionally, the vessel can provide rapid response on O&M interventions without having to wait for neap tides.
Offshore Wind- where the vessel can demonstrate better control and safety during cable laying and trenching operations. The DP system has been developed to provide excellent stability and a unique deck layout for better cable control and handling in harsh environmental conditions with a low risk of excursion.
Offshore Wind Operations and Maintenance – where the vessel’s unique bespoke Rapid DP system, which demonstrated capability during simulation of undertaking crew transfers every 4-6 minutes (compared to 35 minutes for existing vessels). This means the vessel can undertake 10 crew transfers an hour compared to 2 for a conventional vessel, leading to much higher uptime on technician’s hours.
Quote Richard Parkinson, Managing Director of Mojo:
“I am delighted with the performance of the vessel. It has exceeded our expectations during the simulations, with excellent stability and response in DP and manual operations. She is extremely rapid in acceleration, deceleration and turning and very stable in all conditions.
Compared to a conventional vessel she is able to operate with current and wind from any direction, which makes set up on site much quicker and much more flexible. We are planning for the first vessel to be delivered in June 2016”.
