Question 1

A DPO notices the vessel accelerating to starboard with all thrusters showing high starboard demand, even though the setpoint has not changed and the environmental forces are from the port side. What should the DPO conclude and what should be the first action?

Accepted Answer

This is a probable drive-off — the thrusters are demanding in the wrong direction relative to environmental force. Immediately isolate the suspect thruster(s) and switch to joystick; alert master and platform simultaneously High thruster demand opposing the environmental force direction is the textbook drive-off signature. Waiting 60 seconds or switching DP computers while the vessel is accelerating toward a structure wastes the critical response window. Isolation and manual takeover, with simultaneous alerting, is the correct parallel action.

Question 2

What is the fundamental distinction between a DP drive-off and a drift-off?

Accepted Answer

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 This distinction is critical because the responses differ entirely. In a drift-off the vessel is slowing down as fuel/thrust is lost — the risk is manageable drift. In a drive-off the vessel is being actively powered away from position; acceleration can be rapid and momentum builds quickly, making a collision with a nearby structure far more likely before the DPO can respond.

Question 3

Why is a DP drive-off generally considered more dangerous than a drift-off, especially in close proximity to a fixed structure?

Accepted Answer

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 A drifting vessel decelerates as thrust is lost — there is a predictable slowdown. A vessel with thrusters running at full demand in the wrong direction accelerates into the hazard. At 60–80m from a platform, the window from detection to potential impact can be less than 30 seconds in a severe drive-off.