Basic Flashcards
What is Consequence analysis?
- A software function by the DP system.
Why is consequence analysis used
-To assess the ability of a vessel to maintain position after a given failure.
Who uses consequence analysis?
- DP Class 2 and 3 vessels.
- It is required to comply with class regulations.
What is the feed forward function?
-Wind sensors directly sends measurements to the thruster controller.
-Allows fast reaction to rapid changes in wind strength and direction.
What is fan beam?
-Laser positioning system (Range - Bearing).
-Outputs range. And relative bearing to the DP.
-Local positioning-reference system.
What are the main components of a fan beam system.
-Laser Sensor.
-Monitor.
-LED Keypad.
-Processor.
What are the advantages of a fan beam system?
-High accuracy when distance is short.
-Easy to install.
-Passive target and requires no support when installed.
What are the disadvantages of a fan beam system?
-Inoperative when sun shining directly into the lenses.
-Lenses can be affected by consideration, rain and salt spray.
-Vulnerable to fog, snow and heavy rain.
-May be confused by bright lights/reflective items near the target.
What is CyScan?
-Laser positioning system (Range - Bearing).
-Outputs range and reflective bearing to the DP.
-Local position-reference system.
What are the Main components of CyScan?
-Laser Sensor.
-Power Supply.
-PC Console/Monitor
What are the advantages of CyScan?
-High accuracy when distance is short.
-Easy to install.
-Passive target(s) and requires no support when installed.
-Intelligent algorithms built in to avoid false targets.
-Auto-levelling: Compensating for pitch/roll.
What are the disadvantages of CyScan?
-Vulnerable to sun shining directly into the lenses.
-Lenses can be affected by condensation, rain and salt spray.
-Vulnerable to fog, snow and heavy rain.
-Rotor vulnerable to
Ice build up between rotor and gearbox cover.
What is HPR?
- Hydrostatic, Position, Reference
What is HiPAP
-High, Precision, Acoustic, Positioning
What is the Purpose of HRP & HiPAP?
-A HPR/HiPAP system positions a vessel/rig relative to transponder, based on the principle of sound in water.
What is SSBL?
-Super Short Base Line.
What is SBL?
Short, Base, Line
What is LBL?
Long, Base, Line
What are the advantages to SSBL?
-Only requires one transponder/responder.
-Quick to do, only needs calibrated once.
-Easy to use and train people.
-Most vessels have one fitted.
What are the disadvantages of SSBL?
-Requires VRU and Gyro - deep water high accuracy is expensive.
-Position accuracy degrades with increasing water depth.
-Limited on ranges approximately 2.5-4km slant range.
What are the advantages to LBL?
-High positioning accuracy, better than 1m in 1500m depth.
-Position accuracy is independent of Depth.
-Vessel motion compensation not necessary for the LBL calculation.
What are the disadvantages to LBL?
-Time-consuming transponder deployment.
-Calibration after deployment.
-Complicated operating procedures.
-Position update rate not as quick as SSBL.
What are the advantages of a Taut Wire system?
-Accurate.
-Not dependent upon third parties.
-Easily deployed and re-deployed.
What are the disadvantages of a Taut Wire system?
-Wire may bend in strong tide.
-Less accuracy in deep water.
-Limited operational area in shallow water.
-Limitation in use in areas with equipment at seabed.
-The risk of dragging the weight.
