UK-based Guidance Marine says a ‘targetless’ position reference sensor it has developed for dynamic positioning is especially well suited to use on service operation vessels operating in offshore windfarms, but it could have a host of other applications.
Guidance Marine, which has long experience designing and manufacturing local position reference sensors used in the offshore oil and gas market, recently unveiled the new sensor, RangeGuard. Instead of targets on offshore structures, it uses radar reflections from its surroundings to calculate precisely a vessel’s range to the nearest object in its field of view. Combining the information from two sensors allows range and bearing to be calculated and input into the dynamic positioning (DP) system of a vessel. The company claims that RangeGuard is, thus, the first ‘targetless’ DP local position reference sensor (PRS).
Guidance Marine presented a paper at a recent conference on RangeGuard. Dr Sasha Heriot described collaboration between Bernhard Schulte Shipmanagement, Marine Technologies and Guidance Marine that saw two RangeGuard sensors installed on the Bernhard Schulte-managed vessel Ocean Zephyr.
Dr Heriot explained that Hendrick Busshoff, a marine superintendent at Bernhard Schulte Shipmanagement, trained as a master mariner in the offshore oil and gas industry before moving to offshore wind. He recognised the differences in vessel operation in a windfarm compared to an oil field and identified the need for a new type of position reference sensor.
A vessel approaches an offshore wind turbine on DP and, typically, uses differential GPS and a laser PRS to obtain precise position. If poor quality reflector targets are installed on the wind turbine, it can lead to the laser sensor detecting false reflections due to their proximity to other highly reflective surfaces, such as the high-vis jackets of workers on the landing platform and walk-to-work gangway. To overcome this problem, high quality reflective prism targets should replace low quality reflectors, but the cost of installing these on every single wind turbine in a windfarm can be prohibitive. Removing the need for physical targets altogether is a step-change in windfarm navigation.
In the trials it conducted with Bernhard Schulte, Guidance Marine installed two RangeGuard sensors on the starboard side of Ocean Zephyr. The 24 GHz radar sensors send out a low power signal, and the radar reflections from their field of view are detected. By combining information from two sensors, the location of the wind tower relative to the vessel can be calculated precisely.
Data was collected during a sea trial on the Bard 1 offshore windfarm. Although the sensors were not connected into the DP system, the sensors successfully recorded the movements of the vessel. The next stage of the project is now underway at Marine Technologies to connect the sensors into the DP system of the ship.
After the promising results obtained during the trials on Ocean Zephyr, Bernhard Schulte decided to make full use of the potential of RangeGuard and install a fully DP integrated system on its new service operation vessel Windea La Cour.
Guidance Marine has also developed a new, improved version of the long-standing Artemis System. The company’s head of sales, Declan O’Dea, said, “The Mk6 system is the evolution of the Artemis Mk5 system and the latest offering in sensor technology from Guidance Marine. With the addition of the Artemis Mk6 system, our laser and microwave position reference sensors can position vessels safely and effectively from anywhere between 10m and 10,000m.”
The Leicester-based company took over ownership of the Artemis brand, first introduced to the offshore market in 1972, from CHL in 2015 and since then has extensively evaluated the Mk5 system and understood the needs of shuttle tanker and floating, production, storage and offloading (FPSO) operators.
“The system is typically used in the offshore operation of offloading and transportation of oil between shuttle tankers and FPSOs. The Mk6 system is the most complete long-range radar in Artemis product history,” Mr O’Dea explained. The new system, which overcomes GNSS scintillation, boasts an all-weather operating system up to 10km, interchangeable antennas and antenna units, a Guidance Dashboard user interface and is compatible with all existing Mk5 stations. Orders have already been placed by DP integrator, Kongsberg Maritime as well as Teekay, the largest independent operator of FPSO units in the North Sea and fourth largest leased operator in the world. Plans are in now the pipeline to release the Artemis Validator, a compact device designed to quickly and independently verify the operation of an Artemis sensor.
Also recently introduced by the DP specialist is RadaScan View, which was designed to enhance conventional microwave DP reference sensors to provide additional situational awareness directly at the DP operator’s (DPO’s) station.
An evolution of Guidance Marine’s RadaScan technology, the RadaScan View sensor is a combined position reference sensor and navigation radar. The key is evolution, not revolution, says the company – additional useful information without detracting from the already satisfying user experience. By combining the accurate position radar with this navigational view, DPOs are now able to confirm the position of responders with respect to the asset. This reduces the DPO workload during approach and can assist during stationkeeping with optimum vessel positioning.
By introducing the ‘View’ feature to RadaScan, DP operators can achieve a higher level of operational safety for these applications, more choice and higher levels of redundancy, the company claims. Current position references offer a limited view of the ‘real world’ environment. As today’s operations become more and more complex, providing situational awareness to an operator can help prevent an incident by providing early warning and allowing more time to correct a potential issue. Steve Mason, a master and senior DPO at Hornbeck Offshore, said he believed that the View feature “will be a great improvement to the system, especially for platform supply vessels and other vessels that operate in close proximity on DP”. Captain Frode Eineberholm and chief officer Ronny Waage on Østensjø Rederi’s Edda Ferd said, “It is useful when it is foggy and really useful when next to the installation. It helps to see whether or not they are parallel or at an angle to the object.”
Also new from Guidance Marine is an ‘Absolute Signature’ enhancement to its well known CyScan Mk4 laser position reference sensor, which, it claims, can deliver “levels of confidence that were previously unachievable” in laser position reference sensor navigation.
The laser reference technology applied by the company resolves long-standing challenges by providing improved performance during target identification, acquisition and tracking. The absolute signature allows immediate and definitive elimination of clutter.
As the company notes, the synergy between the sensor and the target using AS technology “defines laser performance for DP operations”. Among the key benefits it cites are guaranteed ‘signature lock’ between the laser position reference sensor and the target, automatic target identification and acquisition and the ability to eliminate possible ‘walk-off’ incidents, increase the level of false reflection immunity and reduce turnaround time, thus enhancing operational performance.
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