DP — Walk-to-Work / Offshore Wind Practice Questions

A. W2W is a helicopter transfer method for offshore wind installations

B. W2W refers to transferring crew between two vessels at sea using a gangway

C. W2W is a type of anchor mooring system used near offshore wind farms

D. W2W is the transfer of technicians from a service vessel directly onto a wind turbine generator (WTG) via a motion-compensated gangway, with the vessel holding in DP alongside the WTG transition piece — the challenge is that the vessel must hold extremely close (typically 2–5m) to a fixed structure for extended periods, with technicians physically connecting the vessel and WTG via the gangway

A. DP1 is sufficient since the turbines are fixed and the vessel only needs to maintain a general heading

B. DP3 is the minimum and DP2 is not accepted by any offshore wind operators

C. No minimum DP class applies to W2W operations — it is decided vessel by vessel

D. DP2 is the standard minimum for W2W operations — the consequence of a single failure causing a loss of position while technicians are on the gangway could be fatal (gangway shear, crush, or capsize); the redundancy of DP2 ensures a single equipment failure cannot result in loss of position

A. The DP system must hold position to within ±10m, which is standard for any DP operation

B. The DP system must hold position within very tight tolerances (typically ±1–2m) and maintain heading such that the gangway's compensation range is not exceeded — the gangway has a limited travel envelope, and if the vessel drifts beyond that envelope while technicians are on the gangway, the gangway reaches its end-stop and can no longer compensate, risking a structural failure or injury

C. The gangway compensates fully for any vessel movement — the DP system only needs to maintain general heading

D. The motion-compensated gangway operates independently of the DP system and does not require position accuracy