Question 1

Following a drive-off event that has been manually arrested, the DPO determines a thruster is faulty and wishes to increase standoff distance while the fault is investigated. The OIM demands the vessel hold at 60m to continue operations. What is the DPO's position?

Accepted Answer

The DPO retains independent authority to determine a safe operating distance given the current thruster configuration; an increased standoff for a consequence analysis and ASOG reassessment is not optional and the OIM's commercial preference does not override it Following a drive-off with a degraded thruster configuration, the DPO has both the authority and the duty to refuse operations at the previous working distance until consequence analysis confirms the vessel can safely maintain position with the new WCF. This is the same dual-authority principle established in the DSV diver cascade — the OIM's drilling/operations authority does not extend to overriding the DPO's DP safety domain.

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.