A DPO identifies a probable thruster runaway causing a drive-off. What is the correct immediate first action?

A. Switch the DP system to joystick mode and apply counter-thrust to stop the movement

B. Manually stop or isolate the runaway thruster immediately — this removes the erroneous drive force; the vessel can then be managed with remaining thrusters in joystick or manual mode

C. Wait for the DP system's automatic fault detection to isolate the thruster

D. Shut down all thrusters simultaneously to prevent further deviation

A. A drive-off occurs during manual joystick mode; a drift-off only occurs in DP auto mode

B. A drift-off is always slower than a drive-off

C. A drive-off occurs when a thruster malfunction or DP system error actively propels the vessel away from position against the operator's intent; a drift-off occurs when power or thrust is lost and the vessel moves passively under environmental forces

D. They are two terms for the same event — the vessel leaves its position in both cases

A. Because drive-offs only occur in bad weather when the vessel is already at risk

B. Because a drift-off always results in a controlled shutdown, whereas a drive-off does not

C. Because thruster power is being applied in the wrong direction, accelerating the vessel toward (or away from) the structure — the vessel gains speed rapidly and the DPO has very little time to stop it before impact

D. Because drift-offs are automatically detected by the DP system and corrected; drive-offs are not