Identify vessels from their navigation light configurations and day shapes as required by COLREGS Annexes I, II, and III. Match what you see — a green-over-white vertical pair, a red all-round over a white all-round, a cylinder shape — to the correct vessel type and status: power-driven, sailing, fishing (trawling vs. other), not-under-command (NUC), restricted in ability to manoeuvre (RAM), aground, towing, dredging, or at anchor.
Navigation lights and day shapes are covered by COLREGS Rules 20–31 and tested on every USCG deck officer examination — typically 10–15 questions per sitting. The SVG diagrams show the actual arc geometry of each light, making this the most visual lights-and-shapes drill available online.