Telemetry: Tanker Berthing, Mooring Integrity / Line Tension / Failure Alarm
Ocean Technical Systems Limited (OTS or OceanTech in short) builds instrumentation and control systems to assist safe operations at FPSO mooring and Tanker loading/offloading terminals.
OTS has been supplying monitoring systems for use on FSOs, FPSOs and SPM buoys for over 30 years and to date have supplied in excess of 150 installations worldwide. Assembly is carried out from the OceanTech House in Cheam, Surrey, UK.
With the company’s core skill in radio telemetry, OTS has delivered countless Remote Telemetry Units (RTU), which are capable of both transmitting data from sensors on the buoy and receiving & executing commands from the Base Station. The RTU transmits on a single radio channel in either VHF, UHF, or GHz bands via an omni-directional antenna mounted on an elevated part of the structure. Specially designed for very low power consumption, the RTU is also certified for operation in “Ex” hazardous areas.
Over more than thirty years, OTS systems have evolved from a simple device to measure and transmit the measured load in a Mooring Hawser at a Single Point Mooring terminal (SPM) to comprehensive systems used for FPSO operations:
- Anchor Chain Failure
- Hawser Load Monitoring
- Tanker Berthing Aid
- Fog Navigation Aids
- Pipeline Pressure Surge
- Emergency Shutdown (ESD)
- PLEM Valve Control
The “OSPREY” Tandem / Side-by-Side Tanker Berthing Aid
This DGPS berthing system is suitable for Tanker Berthing at FPSO, FSO, CALM Buoy or jetty. The system provides the mooring master or pilot with accurate information on the tanker’s approach distance, position and speed, including visual and audible alarms on approach speed, collision danger, difference in heading, and early warning of tanker fishtailing.
The precision provided by the “OSPREY” system is more accurate than traditional berthing methods using Laser or Berthing Radar. The “OSPREY” system is capable of implementing its completely self contained Real Time Kinetic (RTK) – Differential Global Positioning (DGPS) system consisting of its own base station permanently installed in a terminal control room, a lightweight PORTABLE unit to be hand carried onto the approaching tanker, and/or a solar powered unit installed on the BUOY.
The three units communicate via integral radio transceivers operating on a single radio frequency (UHF or VHF) providing a bi-directional link between each location. The “OSPREY” Tablet PC also provides the mooring master with a real time display of a “bird’s eye” view of both the Tanker and FPSO during the Berthing and Offloading operations.
The “OMEGA” Turret / Spread Mooring Failure Alarm System
This patented system provides a self contained electronic system to monitor the real time position of a FPSO and through a statistical probability algorithm, compares it against the vessel’s normal excursion envelope, and generates an Alarm on Mooring Line Failure.
The “OMEGA” system uses a high-precision DGPS technique, similar as the “OSPREY” berthing aid, and is able to provide an accurate position and heading of the FPSO. The position of the FPSO or Turret is measured at intervals, and each measurement is marked to one of a large number of geometric pixels. Over a period of time, a pattern (typically donut-shaped) will form, showing the excursion envelope over an area of the seabed in which the mooring lines are located and displayed on a screen. FPSO operators have been found to pair the usage of the “OMEGA” system with traditional methods such as the installations of wired sensors and inclinometers on mooring lines to monitor line tensions and angles.
In the case of Turret-moored FPSO’s, the turret position can be precisely calculated using the known relative position of the turret with the two GPS antennas. Similarly, the “OMEGA” system can be efficiently deployed for Spread-moored vessels, where any significant or rapid change to the geometric “foot print” will trigger off the mooring system alarm.
The “OMEGA” mooring failure monitoring system and the “OSPREY” berthing aid system can be integrated when used on a FPSO.
The “OMEGA” Mooring Line Tension Monitoring System – ANGLE & TENSION
For FPSOs where an in-line tension measurement is undesirable or impractical, the “OMEGA” Mooring Line Tension Monitoring System may be deployed to measure the ANGLE of each anchor leg attached to the Turret or FPSO, and convert the results to TENSION by using data calculated from the Mooring Analysis design.