As DP systems are proliferating into different shipping sectors, owners need to deploy methods of preventing satellite signal interference
With the expanded use of dynamic positioning (DP) in multiple sectors of the maritime industry, the reliability of positioning information has never been more important.
DP, once the domain of the offshore oil and gas sector, is increasingly used on windfarm support vessels, shuttle tankers during offshore loading and cruise ships to assist berthing.
These vessels need accurate and precise position reference systems with redundancy in case vessel operators encounter issues with Global Navigation Satellite System (GNSS) service signals.
GNSS can be spoofed and jammed leading to a loss of positioning reference for DP systems. There are four main GNSS services, Global Positioning System (GPS), Glonass, Beidou or European Space Agency (ESA)’s Galileo to provide redundancy in satellite transmissions. These are augmented with differential GNSS and reference sensors.
Genting Cruise Lines, incorporating the brands Dream Cruises, Star Cruises and Crystal Cruises, has integrated bridge systems (IBS), automated steering and DP on its fleets of ships. Most of its cruise ships have Wärtsilä NACOS Platinum IBS with ECDIS, radar, conning, track-pilot and sensors. These are all integrated into one onboard network, says Genting Cruise Lines vice president for marine operations and safety Captain Havard Ramsoy.
Genting’s ships have Fugro equipment for accurate and optimised docking operations and Eniram services for speed, trim and voyage optimisation. Navtor supplies electronic navigational charts (ENCs) and publications and Napa is used for stability and electronic logbooks.
“Docking systems give the ship position with high accuracy and speed inputs without delay”
“On our larger vessels we use Wärtsilä’s DP systems,” says Capt Ramsoy. “For safe and efficient docking, the ships are also equipped with Fugro satellite positioning and docking systems.” These are required to safely berth cruise ships in harbours worldwide to reduce accident risks and passenger discomfort.
“These docking systems give the ship position with high accuracy and speed inputs without delay,” says Capt Ramsoy. “Together with predictor software, these provide safer and more efficient berthing.”
In a different application, AET installed DP2 positioning systems on its latest Suezmax shuttle tankers under construction by Samsung Heavy Industries in South Korea. These 152,000-dwt tankers will be on DP mode during offshore loading of crude for Brazilian state energy group Petrobras.
The first of four of these shuttle tankers on order, Eagle Petrolina, was delivered in May 2020. It is a second-generation shuttle tanker in AET’s fleet. AET operates six other DP shuttle tankers and has a further 10 shuttle tankers under construction to be delivered between 2020 to 2022.
For precise positioning, some offshore support vessels and drilling rigs use GNSS with transmissions for four constellations and the growing QZSS system. They also have anti-jamming technology. Hexagon Autonomy & Positioning has developed GAIT (GPS anti-jamming technology) under its Veripos brand. “We provide anti-jamming antennas to many of our customers among other positioning systems,” says Hexagon Autonomy & Positioning vice president for marine sales Richard Turner. “It is used widely in the eastern Mediterranean due to the jamming there at the moment.”
Veripos GAJT-710MS mitigates intentional and unintentional jamming or interference from excessive noise that overpowers the low-power GPS signals and degrades GPS position, navigation and time availability.
GAJT-710MS combines an antenna array and null forming electronics into a marine hardened enclosure suitable for installation on a wide range of marine vessels. It mitigates interference by creating nulls in the antenna gain pattern in the direction of the jammers, which provides significant anti-jam protection.
Laser position reference augments GNSS services with measurements of range and bearing to a set of geographically referenced reflectors. Wärtsilä’s Guidance Marine’s CyScan GeoLock sensor provides position references without risk of spoofing, interference or loss of signal as it uses a laser rather than satellites.
It can be used for precise vessel manoeuvres in ports, terminals or around an offshore drilling rig or production system, with redundancy against GNSS failure mode. It has been installed for the Folgefonn auto-docking project. A minimum of three prism-reflector targets are set up in the port and their location is input into the CyScan GeoLock sensor as a configuration file.
When the ship is near the quayside or terminal, the CyScan GeoLock sensor automatically starts tracking. It compares the geometric pattern produced by its range and bearing measurements of detected reflectors with the corresponding geometric pattern of the surveyed reflectors in the configuration file.
Once a match is found, the reflectors are accepted into the sensor’s tracking solution and the sensor starts to produce a position reference.
Another alternative comes from inertial instruments. Sonardyne International provides technologies for autonomous vessel positioning and navigation in the event of disruption to a GNSS signal.
In a Q2 2020 project funded by the UK’s national Defence and Security Accelerator, Sonardyne International’s Sprint-Nav hybrid inertial navigation instrument was integrated with a Sea-Kit X-class unmanned surface vehicle (USV) and tested against local real-time kinematic GPS positioning.
This solution adapts technology already used by unmanned underwater vehicles which operate in GNSS-denied environments. Sea-Kit is working with survey specialist Fugro to develop a range of USVs for offshore applications.
Romanian Center for Training and Development of Naval Transport Personnel (Ceronav) is investing in a DP teaching suite for its new maritime campus. It has contracted Kongsberg Digital to supply simulators to its existing premises before being relocated to a new, dedicated offshore marine simulation facility on the shores of Lake Mamaia, near Constanţa.
For this project, Kongsberg will supply K-Sim DP manoeuvring Class A simulator and DP offshore training scheme. It will also supply eight K-Pos DP Class C desktop simulators for basic DP training, including instructor stations to manage the exercises.
Ceronav associate professor and general manager Ovidiu Sorin Cupsa says these Kongsberg simulators will be used to “train students, most of whom are crew with long experience as DP operators at sea, with a need for retraining and internationally approved certificates”. The simulators are due to be delivered on 25 August.
Guidance published for FMEAs of DP systems
Oil Companies International Marine Forum (OCIMF) has published guidance on Failure Modes and Effects Analysis (FMEA) for dynamic positioning (DP) systems.
This follows heated discussions about the effectiveness, accuracy and reliability of FMEA documents and processes during the annual European Dynamic Positioning Conferences, hosted by Riviera Maritime Media.
FMEA is a tool used by reliability engineers throughout the design process of DP systems. Codes, standards and practices require single fault tolerance of DP vessels to be documented in a FMEA.
OCIMF published DP FMEA Assurance Framework Risk-based Guidance on 23 June in Riviera’s Whitepapers website. This outlines the assurance requirements for FMEAs based on broad industry collaboration to improve safety in the industry.
It provides a methodology for identifying vulnerabilities including common failures of FMEAs, assurance periodic verification and update requirements. This document outlines standard format expectations, including worksheets and redundancy verification tables.
It also includes appendices of examples of presentation formats, statement of compliance and operating instructions for FMEAs.
“This paper aims to improve safety by addressing the assurance of DP FMEA quality by requiring identified pertinent information to be presented in a prescribed format,” says OCIMF director Rob Drysdale.
“It is expected to be used to strengthen and streamline the DP sections of OCIMF’s Offshore Vessel Inspection Database and Offshore Vessel Management Self-Assessment process, including training of assurance providers.”