OSPREY - SINGLE POINT MOORING

Tanker Berthing And Position Tracking

OSPREY - The DGPS Tanker Berthing Aid

With the significant development of a reliable global satellite based positioning network GPS technology is now an essential tool in almost all forms of modern position referencing and tracking systems. have adapted this technology to produce a flexible and cost-efficient means of monitoring the relative position of a tanker during berthing at a FPSO.

The system is completely self contained and consists of a BASE STATION permanently installed on the FPSO and a lightweight PORTABLE unit to be hand carried onto the approaching tanker. The two units communicate via integral radio transceivers operating on a single UHF or VHF frequency and both units provide a real time graphical display of the berthing process with sub meter positional accuracy.

The system provides the following information:

 Relative distance (CLOSEST POINT) between SPM and tanker
 Relative speed and angle of tanker approach
 Difference in relative heading (angle)
 Absolute tanker heading
 Absolute tanker speed, direction, and acceleration
 SPM mooring position
 Hawser tension (with load pin installed on buoy)

The system provides two basic functions, the first as a berthing aid providing precise information on approach distance, position, and speed. The second is for use as a mooring aid providing audible and visual alarms on collision danger, and more importantly a difference in heading alarm, giving a vital early warning of tanker fishtailing.

If the SPM is fitted with a hawser tension monitor the signal may be transmitted to the tanker unit for display. Again a vital indicator for safe loading. Finally the portable unit is fitted with two pushbuttons that may be user defined e.g. pump control or ESD functions.

   

Tanker Portable Unit

The tanker portable unit, now a second generation design, consists of a highly integrated device housed in a sealed aluminium briefcase. The unit contains an embedded microprocessor with full colour TFT liquid crystal touch screen, a GPS satellite receiver, a radio transceiver for communication to the SPM, and a gyroscope compass to determine the vessel heading. All internal components are shock mounted and contain NO moving parts to minimise vibration susceptibility. The unit includes all necessary cables and antennas for operation and once on board the tanker the unit can be deployed on the bridge in less than ten minutes ready for use. Apart from external power there are NO physical connections to the tanker ensuring 100% compatibility with ANY vessel.

 Microsoft Windows NT embedded operating system
 266MHz Intel Tillamook Pentium processor
 XGA TFT colour LCD screen
 Impact resistant TOUCH screen interface
 Internal DGPS receiver
 Internal 1W radio transceiver
 Internal gyroscope compass
 Internal loud speaker
 Manual ESD I and ESD II pushbuttons
 AC/DC wide input power supply
 External UHF/GPS antenna with magnetic and clamp fixing

The system employs Microsoft Windows for the graphical user interface providing a familiar environment for the majority of users and can overlay the moving tanker on scanned marine chart of the area for immediate points of reference. User configurable alarm limits are available for each of the above which can sound an audible alarm at both base station and portable unit.

Typical Operating Display

Both the tanker and base station use Microsoft Windows NT as the graphical user interface running the OSPREY application software. The software has been specifically written to be user friendly and with the touch screen interface a novice can master the system in minutes. All options are accessible via menu toolbars which allow the operator to call up any parameter in a small data window at a moment notice.

Two typical screens are shown below. They both detail the tanker on approach to the SPM buoy. The approach distance, speed, and bearing are displayed along with the SPM turntable heading and the tanker heading. With additional instruments on the SPM the wind speed and direction and sea current speed and direction may also be displayed. All provide additional information during berthing.

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Vessel Profile

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To assist the pilot in deploying the tanker unit the system makes use of VESSEL PROFILES to record the dimensions of the tanker and the previous position of the GPS antenna. The ultimate accuracy of the system depends on how accurately the GPS antenna is placed on the tanker. The configuration screen attempts to assist to operator by asking for the length and breadth of the tanker and then the position of the GPS antenna. Once recorded the configuration may be saved as a PROFILE identified by the vessel name. Thus on the vessel's return visit the configuration may be recalled rather than re entered.

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To assist the operator to align the portable unit's gyroscope the window shown on the left may be called at any time to let the operator make a heading correction.

The System

The OSPREY system consists of three units, a non moving base station to provide an absolute reference for the differential GPS system, a unit on the SPM buoy, and the tanker portable unit. The base station generates DGPS correction factors which are then transmitted to the other units to correct their position to a sub meter accuracy.

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Buoy Unit

The buoy equipment consists of a self contained, solar powered unit, containing an embedded microprocessor, a GPS satellite receiver, and a radio transceiver. All components are housed in a rugged marine protected outer enclosure suitable for drop installation onto the SPM turntable. All components are shock mounted and contain NO moving parts to minimise vibration susceptibility. In addition to the buoy position, the hawser load, wind speed/direction, and sea current speed/direction may be monitored and transmitted to the other units for display.

Base Station Unit

The base station unit is a self contained device, suitable for either desk or rack mounting, containing an embedded microprocessor, a GPS satellite receiver, and a radio transceiver. All internal components are shock mounted and contain NO moving parts to minimise vibration susceptibility. The unit includes all necessary cables and antennas for operation simplifying the installation. As standard the base station is not supplied with an operator interface. However if the berthing screens are required to be seen at the terminal a desk top computer may be supplied which can connect to the base station with a standard CAT 5 Ethernet cable.

Technical Specification

SYSTEM PERFORMANCE

Relative positionbetter than 0.1 m typical
Relative bearingbetter than 1 typical
Relative speed of approachbetter than 0.01 m/s typical
Tanker absolute heading 1 typical
Tanker absolute speedbetter than 0.01 m/s typical
FPSO absolute heading 1 typical (dependant on FPSO gyro)



TANKER PORTABLE UNIT

Portable containerCustom anodised aluminium carry case
Size458L x 330H x 129W mm
Weight9.7 kg
Power85-264 VAC 47-63Hz 50W max OR 18-36 VDC 2.0A max
Operating systemMicrosoft Windows NT Embedded
Micro ProcessorIntel Tillamook Pentium 266Mhz in EBX format
Mass storage80MB silicon disk with NTFS format
Graphic DisplayActive matrix LCD panel XGA 16bit colour
Touch ScreenGuided acoustic wave on 1mm glass plate
Radio transceiver425-475Mhz (typical)
Transmit power1W
Data rate9,600 bps over the air
DGPS Receiver12 channel GPS receiver operating in RTK relative differential mode with RTCM SC-104 correction factors.
RTCM update period1s typical.
Heading (compass)Internal non magnetic gyroscope
Heading accuracybetter than 0.6 deg/hr random drift



ENVIRONMENTAL DATA

Shock10g 11ms sine
Vibration3-500 Hz 0.41 grms
Ingress protectionIP55 (dust and moisture)
Ingress protection in transit caseIP68 (immersion to 10m)
Temperature0-40 C
Humidity5-93% non-condensing
AltitudeSea level
Drop100mm on four corners
Drop in transit case600mm on four corners



BASE STATION UNIT

EnclosurePainted steel 19" compatible card frame
Size483W x 88H x 390D mm (2U)
Weight7.3 kg
Power85-264 VAC 47-63Hz 50W max
Operating systemMicrosoft Windows NT Embedded
Micro ProcessorIntel Tillamook Pentium 266Mhz in EBX format
Mass storage80MB silicon disk with NTFS format
External DisplayXGA 16bit colour on VGA D-TYPE connector
Keyboard/MousePS/2 connectors
Ethernet10Base-T on RJ-45 connector
Radio transceiver425-475Mhz (typical)
Transmit Power1W
Data rate9,600 bps over the air
DGPS Base station12 channel GPS receiver operating in RTK relative differential mode generating RTCM SC-104 correction factors type 1,3,9,18,19.
RTCM update period1s typical.
Gyroscope inputNMEA-0183 protocol, RS422 four wire.
Hawser load input4-20mA current loop 100 ohm sense
ESD outputClean contact relay 1A max, pulsed.



OPERATOR DISPLAY

ManufactureToshiba Equium 2000
Size350W x 212D x 389H mm
Weight5.8 kg
ProcessorIntel Celeron 466MHz
DisplaySlimeline 15" TFT LCD
Hard disk / Ram6 GB / 64 MB
CD ROM24x
Ethernet10base-T RJ-45
SoundInternal speakers
Power100-240 VAC
Operating systemMicrosoft Windows 98



PRINTER

PrinterHP Deskjet 970Cxi
Size440W x 370D x 196H mm
Weight5.85 kg




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