Loss of propulsion transforms a vessel from a regulated traffic participant into a drifting hazard under COLREGs Rule 27. Correct initial actions — NUC signals, urgency communication, and systematic engineering diagnosis — determine whether the situation is controlled or escalates to a collision or grounding. This tree follows SOLAS Chapter V, ISM Code Element 8, and COLREGs.
Sources: COLREGs 1972, Rule 27 (vessels not under command or restricted in their ability to manoeuvre); SOLAS Consolidated Edition 2020, Reg V/34 (safe navigation and avoidance of dangerous situations), Reg V/34-1; ISM Code (Resolution A.741(18) as amended) Element 8 (emergency preparedness); MARPOL Annex I Reg 37 (SOPEP), Annex VI Reg 14 (sulphur content ECA); IMO Resolution A.890(21) (Principles of Safe Manning). See also NUC signals, LOF salvage, and COLREGs Rule 27.