9.1 Auto DP Mode

Auto DP is the default station-keeping mode for critical work

Auto DP (also called full automatic DP, automatic position and heading control, or similar vendor labels) is the control mode in which the DP system automatically maintains the vessel’s position and heading at selected setpoints. In the three degrees of freedom that matter for station-keeping, the controller continuously closes the loop on:

The operator does not continuously push a joystick to hold station. Instead the operator selects position and heading setpoints (or freezes present position/heading as setpoints), enables thrusters and references, and monitors the system while the controller generates force demands and thrust allocation logic (TAL) distributes them among enabled thrusters.

What “full automatic” does and does not mean

Does mean:

• Continuous closed-loop correction of surge, sway, and yaw toward setpoints
• Use of the mathematical model, estimator (often Kalman-based), PRS, gyro, wind, and MRU inputs as designed
• Automatic thruster allocation within enable/power/forbidden-zone limits
• Operator focus on supervision, alarms, weather, and operational status—not hand-flying every thruster

Does not mean:

• The system is unsupervised or “set and forget” for hours without watchkeeping
• Every failure is self-healing without DPO action
• Auto DP is always available regardless of reference quality, thruster set, or power plant health
• The vessel cannot move—setpoints can be changed deliberately (slow moves, approach tracks) while remaining in automatic control

Contrast with joystick mode (next section), where the operator commands translation (and often heading) manually while TAL still allocates thrusters. Contrast also with pure manual thruster control, where individual levers or local panels drive units without the DP position loop.

When Auto DP is used

Auto DP is the mode of choice whenever the operational goal is stable station-keeping or controlled automatic manoeuvring under DP:

Auto DP is not always the right first mode during approach from open water, during gross repositioning when the operator wants direct feel of force, or when references are degraded and the DPO must take immediate manual combined thruster control (joystick or IJS). Mode selection is covered in Section 9.3; the principle here is: Auto DP for sustained automatic hold/track once the system is ready.

Enabling Auto DP and the settling period

A common exam and simulator failure is selecting Auto DP and immediately assuming the footprint is “locked.” Real systems need a short settling interval after enable or after major changes.

Typical enable sequence concepts (vendor menus differ; the logic is common):

1. Confirm power and thrusters available; thrusters enabled for DP
2. Confirm adequate independent PRS online and selected
3. Confirm gyros, wind, MRU healthy
4. Build or accept the model estimate (vessel may have been in joystick or another mode while the model adapts)
5. Set or freeze position setpoint and heading setpoint (present position / present heading is common when already roughly on location)
6. Select Auto DP (or Auto Position + Auto Heading, depending on HMI)
7. Watch settling: thruster activity often peaks briefly as the controller corrects residual errors, then should quiet toward a steady allocation pattern for the weather

During settling, expect:

• Temporary thruster bias or higher RPM while errors shrink
• Model vs measured residuals to converge toward normal bands
• Possible soft alarms if gains or reference noise are high—investigate, do not ignore
• Footprint plots or position history to show oscillation damping rather than growing walk-off

Do not start critical simultaneous operations (hose connect, dive basket launch under tight offset limits, heavy lift within a tight watch circle) in the first seconds after enable. Allow the system—and yourself—to confirm that Auto DP is actually holding.

Gains and model considerations (conceptual level)

Induction exams do not ask you to tune PID coefficients by number. They do expect conceptual understanding that controller gains and model quality change how Auto DP behaves.

Key exam idea: if thrusters thrash after Auto DP enable with good weather, think noise, gains, or settling, not instantly “drive-off.” If the vessel slowly walks off with thrusters hard over, think capability vs weather, bad reference, thruster not producing, or wrong setpoint—not “turn gains up blindly.”

Alarms while in Auto DP

Auto DP does not silence the alarm philosophy. Common families of alarms while automatic control is engaged:

[!IMPORTANT] An alarm in Auto DP is not automatically a reason to stay in Auto “because the computer is still running.” Consequence analysis or ASOG may require stop work, change setpoint/heading, drop to joystick, or escape while thrusters still respond.

Worked Auto DP scenarios

Scenario 1 — Clean enable. Vessel is 20 m from setpoint after joystick approach. DPO freezes present position as setpoint only after PRS are stable, enables Auto DP, watches thrusters settle for a short period, confirms footprint within limits, then allows deck work to start. Correct discipline.

Scenario 2 — Enable during wild PRS. DPO selects Auto DP while one laser reference is swinging. Thrusters thrash; position alarm follows. Correct action is deselect the bad PRS and re-settle, not raise gains or blame allocation alone.

Scenario 3 — Alarm during steady Auto DP. Consequence analysis warns that after worst-case thruster loss, remaining capability is insufficient in rising wind. Work stops or degrades per ASOG even though Auto DP is still holding now.

Exam traps for Auto DP

Bottom line: Auto DP is full automatic control of surge, sway, and yaw to position and heading setpoints. Enable it when the plant is ready, settle after enable, understand gains and model only at the response/stability level, and treat alarms as reasons to think and act—not as background colour on the HMI.