Free DPO Exam Flashcards

The Nautical Institute (NI) in London. It accredits the training centres, issues the DP logbook and awards the certificate. IMCA publishes operating guidance such as M103 and M117 that vessels and charterers follow, but it certifies no individual DPO.

A: DP Induction course plus online examination. B: minimum 60 DP sea time days plus the logbook task section. C: DP Simulator course with online examination and practical assessment. D: 60 further DP sea time days. E: Statement of Suitability signed by the Master, then application to the NI.

After a minimum of 28 hours of tuition you sit an online examination at the training centre: 40 multiple-choice questions in 1 hour 15 minutes, pass mark 70%. Passing releases the NI DP logbook, and no DP sea time is accepted until the course is complete in its entirety.

Three ways: the DP Set-up Practical Assessment as the course progresses, an online examination of 30 multiple-choice questions in 1 hour at 70%, and formative brief/debrief feedback. The practical assessment cannot be retaken - failing it means repeating the whole Simulator course.

At least two hours of active or passive DP training that day under a certificated DPO. Only one day may be claimed however long you work. At least 75% of claimed time must be active; passive time is capped at 25% and at 30 days, and only in Phase B. Time in DP autopilot mode never counts.

The class of vessel your 120 DP sea time days were served on. Unlimited needs at least 60 days on DP2 or DP3 vessels, including the final 30 days before Phase E. Limited means fewer than 60 of those days were on DP2/3. Restricted to Unclassed covers unclassed or DP class 0 vessels.

Automatic control of a vessel's position and heading using its own thrusters and propellers alone, with no anchors or moorings. A computer compares measured position and heading against the wanted setpoint and allocates thrust to close the error.

A floating vessel moves in surge, sway, heave, roll, pitch and yaw. DP controls only the three horizontal motions - surge, sway and yaw. Heave, roll and pitch are measured so the system can correct its sensor readings, but they are monitored rather than controlled.

Operator, DP computer (controller), operator station or HMI, position reference systems, sensors, power supply and thrusters. The operator is deliberately listed as a component: DP is a manned system, and the DPO is expected to monitor and intervene, not merely watch.

Manual thruster levers, joystick, independent joystick (a separate backup system), semi-automatic (auto heading with manual surge and sway, or the reverse) and full automatic. Specialist modes add ROV/target follow, track follow, minimum power (weathervane) and riser angle monitoring.

The DP builds a mathematical model of how the vessel responds to thrust and environment. If every position reference is lost or rejected, it holds station on the model alone. That is a short-term bridge only: error grows as the real environment departs from the modelled one.

The residual force the system cannot explain from measured wind and modelled motion, shown as a current vector. It absorbs every unmeasured force - swell, thruster interaction, a mistuned model, a drifting reference - so it is not the true tidal stream and must not be read as one.

A function required on equipment class 2 and 3 vessels. It continuously recalculates whether the remaining thrust would hold position in the present weather if the defined worst case failure occurred, and alarms when it would not. It must not be disabled during class 2 or 3 DP operations.

Two main tools: auto-starting standby generators as load rises toward the limit, and auto limit or power chop, which caps or sheds thruster demand faster than an engine can start. Both buy time - the DPO must still reduce demand and reconfigure if the load stays high.

Spinning reserve is the unused capacity of the generators already running. It is what absorbs the load step when a generator or bus is lost, so DP planning sizes it against the worst case failure. Installed power sitting on stopped engines is not reserve.

Tunnel thrusters give athwartships thrust only and lose effect with forward speed or shallow draught. Azimuth and Azipod units give thrust through 360 degrees. Voith Schneider units change thrust direction almost instantly. Main propellers with rudders give mainly surge. The mix shapes the capability plot.

Setpoint is what the DP commanded; feedback is the actual rpm, pitch or azimuth. The system allocates thrust assuming the command was met, so a thruster that stops following its setpoint quietly removes thrust from the solution. Catching the divergence early is what prevents a slow excursion.

Absolute systems (DGNSS, LBL acoustics, taut wire to the seabed) fix the vessel against the earth. Relative systems (laser, microwave radar, relative DGNSS, USBL to a moving target) fix it against another object. Working alongside a moving structure needs a relative reference.

A reference station at a known point measures satellite range errors and broadcasts corrections, which the vessel applies to remove most orbit, clock and atmospheric error. The correction link therefore matters as much as the satellites: lose corrections and you are back to uncorrected GNSS.

Ionospheric scintillation and solar activity, multipath off the ship and nearby structures, satellites blocked by cranes or flare towers, lost or ageing differential corrections, and interference or jamming. Watch the quality figures - satellite count, HDOP, correction age - not just the position.

Both vessels compute GNSS positions and exchange them over a radio link, so the DP works with the range and bearing between them rather than absolute coordinates. Standard for shuttle tanker work at an FPSO, where the target itself moves and absolute position would not hold the separation.

An operator station drives a transceiver connected to a hull-mounted transducer, usually on a lowerable pole. It interrogates a seabed transponder and times the acoustic reply to derive range and bearing. Some inertial-acoustic systems can work without a seabed beacon.

USBL/SSBL: one transducer derives range and bearing from phase differences across its elements - simple, but accuracy falls with depth. SBL: several transducers spread along the hull form the baseline. LBL: an array of seabed transponders gives the best accuracy over a field, at the cost of deployment and calibration.

A transponder replies to an acoustic interrogation from the vessel. A responder is triggered instead by a hard-wired electrical pulse, which removes the interrogation travel time and reduces acoustic noise in the water. A pinger or beacon transmits on its own with no interrogation at all.

Aeration under the hull, thruster and machinery noise, other acoustic systems working in the field, ray bending through temperature and salinity layers, and battery life on the seabed unit. Accuracy also falls as the vessel moves toward the edge of the beacon's cone and as depth increases.

A depressor weight is lowered to the seabed and the wire held under constant tension; gimbal sensors measure the wire angle in two axes, and angle plus deployed length gives the horizontal offset. Limited by water depth, current bowing the wire, and excursions large enough to drag the weight.

A rotating laser measures range and bearing to reflective prisms on the target structure; targetless systems such as SceneScan and SpotScan lock onto the structure's own shape instead. Fog, heavy rain, snow and sun glare cut the range, and stray reflective surfaces can steal the lock.

FMCW radar ranges on responder targets fitted to the installation, with targetless variants such as RangeGuard. Fog, rain and glare barely affect it, while a laser usually gives finer accuracy close in and in clear air - which is exactly why the two are chosen as a weather-diverse pair.

An inertial unit measures the vessel's own accelerations and rotations and is blended with acoustic or GNSS updates. It smooths dropouts, flags implausible jumps and raises the update rate. Unaided inertial position drifts steadily, so it supplements references rather than replacing them.

The system weights and pools accepted references, and with three or more it can apply median rejection to drop the odd one out. Two disagreeing references show that something is wrong but not which. Independence matters too: three receivers sharing one correction service share one failure.

Heading is the one input DP cannot work without, because thrust is allocated in the vessel's own axes. Equipment class 2 and 3 vessels carry three gyro compasses so voting logic can identify and reject a drifting or failed unit instead of merely detecting a disagreement.

It measures pitch, roll and heave. DP does not control those motions - it uses them to correct measurements from sensors mounted away from the centre of rotation. An HPR transducer or GNSS antenna swings in a seaway, and without MRU correction the reported position would oscillate.

Anemometer input lets the DP counter a gust as it arrives instead of waiting for a position error to build - that is feed-forward. Sensors read wrong when shadowed by structures, cranes or the vessel itself, and deselecting a faulty one hands its share of the work to the slower feedback loop.

Class 1: loss of position may occur after a single fault. Class 2: no loss of position from a single fault in any active component or system. Class 3: as class 2, plus no loss from fire or flooding affecting all components in any one watertight compartment or fire subdivision.

MSC.1/Circ.1580 (2017) applies to vessels and units constructed on or after 9 June 2017. Vessels built from 1 July 1994 up to that date may continue under MSC/Circ.645. The equipment class definitions carry across, so check the vessel's DP documentation for the guideline it was designed against.

At least three position reference systems installed and simultaneously available to the DP control system, and where two or more are required they must not all work on the same principle. On class 3 vessels one reference feeds the backup DP control station, which sits behind an A-60 division.

WCFDI is the design target: the minimum DP capability that must survive the worst single failure. WCF is what the FMEA and trials actually prove for the vessel as built and configured. Operations are planned on the proven WCF, and any shortfall against the design intent becomes an operating limit.

The FMEA is required for class 2 and 3, identifies the worst case failure, and is the basis of the ASOG. Annual trials retest that redundancy in service - under the IMO guidelines within three months either side of the anniversary date - because maintenance and modification quietly erode it.

A capability plot is calculated: the wind, sea and current the vessel can hold from each direction, drawn intact and after defined failures. A footprint plot is measured: the actual spread of positions held in the real conditions at the time. One is a prediction, the other is evidence.

Approach with speed and distance under control, work the pre-DP checklist, and select and settle the position references well before entering the 500 m zone. A drift test shows how wind and current actually push the vessel before you commit. A rushed set-up is the classic incident precursor.

A vessel- and task-specific table of environmental, equipment and operational limits, each tied to a status level and to the action required - continue, prepare to suspend, terminate. It is built from the vessel's FMEA and proven worst case failure, so it never transfers unchanged to another vessel or job.

Critical activity mode is the most fault-tolerant configuration - split buses, redundant references, generators online - used where loss of position has severe consequences. Task appropriate mode accepts, after a documented risk assessment, a configuration in which a single failure could exceed the worst case failure.

Hand over at the console, not in passing: vessel and DP status, alert status and status board, references in use and rejected, power configuration, weather trend and forecast, field and vessel operations in progress, and outstanding faults. The relieving DPO completes the checklist before accepting the watch.

From the task, not the DP system. Diver umbilical length and thruster proximity, riser angle and BOP disconnect limits on a drillship, cable or pipe tension, hawser tension in offshore loading. Those tensions feed the DP as external force references, and the limits are what the ASOG is written around.

Information messages report normal events, warnings flag a condition needing attention, alarms demand action now. Alert status is separate: a board, commonly green/blue/amber/red, that tells the whole field team the vessel's condition. Colours and triggers are vessel-specific, so read the ASOG.

A drive-off is powered: thrusters actively push the vessel off position, usually from a bad reference or a control fault, so the response is to remove the bad input or take manual control fast. A drift-off is loss of thrust, leaving the environment to push the vessel away. Drive-off leaves far less time.

One reference rejected by voting is a fault to investigate, not an emergency. Losing enough of them leaves the DP on model control - dead reckoning, with error growing unseen because nothing independent can detect the excursion. Decide the response in the plan: restore a reference, reduce exposure, or terminate.

A full blackout removes all thrust and begins a drift-off. Losing a bus or a generator removes only part of it, but may still put the vessel beyond its worst case failure. Check remaining thrust against the environment, then raise the alert status and tell the field team immediately - not after recovery.

Terminate on the plan, not on hope. The ASOG defines the status change and the required action; planning defines how long a safe termination takes - diver recovered, riser disconnected, gangway lifted - and the escape route clear of the structure. If time available is less than time needed, stop earlier.

Log the event with its alarms and printer output, the references and thrusters affected, and the actions taken, in the DP logbook and the fault log. Vessel reports feed the IMCA station-keeping incident scheme, whose published analysis is the industry's main evidence base on how DP actually fails.