What position reference systems are typically used for W2W DP operations at close proximity to a WTG, and why are GNSS references insufficient alone?

A. Close proximity W2W operations require high-accuracy relative references: laser/optical tracking systems or radar-based sensors that provide real-time vessel position relative to the WTG structure directly — GNSS alone is insufficient because GNSS accuracy (±2–5m CEP) is comparable to or larger than the W2W gangway range, meaning a GNSS-only DP system cannot reliably keep the vessel within the required position tolerance

B. DGNSS (differential GPS) provides sufficient accuracy for all W2W operations without additional sensors

C. Taut wire is the required reference for all W2W operations

D. Standard GNSS (GPS/GLONASS) is fully sufficient for W2W operations

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