Question 1

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 2

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.

Question 3

What console indication should alert a DPO to a possible drive-off, as opposed to an environmental excursion or simple drift?

Accepted Answer

Thruster demand showing high or maximum output in a direction away from the setpoint, with vessel position accelerating away from position rather than decelerating toward it In a drift-off, thrusters demand reduces as power is lost. In a drive-off, thrusters are demanding maximum output — but the output is erroneous. The key signature is high thruster demand combined with accelerating position deviation in the same direction, rather than the vessel fighting to return to setpoint.

DP — Drive-Off Fundamentals Practice Questions