DPO DPO Alarms, Fault Diagnosis & System Troubleshooting 2 — Questions and Answers
Question 1: During DP operations, a sudden loss of one power bus in a DP-2 vessel should result in:
- Total loss of DP capability
- A safe reduction in available thrust but continued DP operation on the remaining bus (Correct answer)
- Immediate manual takeover only
- Activation of the anchor system
Correct answer: A safe reduction in available thrust but continued DP operation on the remaining bus
DP-2 class vessels are designed so that a single power failure does not cause loss of position; the remaining bus supports continued DP operation with reduced but adequate thrust.
Question 2: A DP operator notices the vessel is consuming unusually high thruster power to maintain position without a significant change in weather. The most likely cause is:
- A GPS satellite outage
- An undetected current increase, propeller fouling, or a thruster operating below efficiency (Correct answer)
- The vessel has exceeded its DWT limit
- The gyrocompass is drifting
Correct answer: An undetected current increase, propeller fouling, or a thruster operating below efficiency
Higher-than-expected power demand without apparent environmental change can indicate a fouled propeller, reduced thruster efficiency, or an unmonitored current that the environmental model has not captured.
Question 3: What action should a DPO take when a reference system shows a 'loss of lock' alarm during critical DP operations?
- Immediately increase speed to relocate
- Inhibit the alarming reference and verify that remaining references are stable and sufficient (Correct answer)
- Switch the DP system to joystick mode
- Reduce thruster output
Correct answer: Inhibit the alarming reference and verify that remaining references are stable and sufficient
When a reference loses lock, it should be inhibited to prevent corrupted data entering the DP position filter, and the operator must verify remaining references maintain adequate coverage.
Question 4: On a DP vessel, the term 'UPS' in the context of the control system refers to:
- Upper Positioning System
- Uninterruptible Power Supply, which maintains power to DP computers during a brief power interruption (Correct answer)
- Underwater Propulsion Signal
- Universal Positioning Software
Correct answer: Uninterruptible Power Supply, which maintains power to DP computers during a brief power interruption
A UPS (Uninterruptible Power Supply) provides short-term battery-backed power to DP computers and control systems, preventing loss of the DP system during brief power transients.
Question 5: If the DP computer's position filter diverges from actual vessel position due to accumulated reference errors, the operator can correct this by:
- Restarting the main engines
- Performing a 'position reset' or reinitiating the filter after confirming a reliable reference (Correct answer)
- Switching heading control to manual
- Disconnecting all thrusters
Correct answer: Performing a 'position reset' or reinitiating the filter after confirming a reliable reference
Resetting or reinitiating the DP position filter with a validated reference allows the system to re-synchronize its estimated position with the vessel's actual location.
Question 6: Which alarm indicates that the mathematical model used by the DP system to predict vessel behavior has significantly diverged from actual sensor measurements?
- Heading alarm
- Model error alarm (Correct answer)
- Thruster overload alarm
- DGPS fix quality alarm
Correct answer: Model error alarm
A model error alarm signals that the DP Kalman filter's internal vessel model no longer matches measured sensor data, potentially indicating a sensor fault or unusual environmental condition.
DPO DPO Alarms, Fault Diagnosis & System Troubleshooting 2
During DP operations, a sudden loss of one power bus in a DP-2 vessel should result in: