Twenty-seven scenarios built on real CPA/TCPA mathematics and real light-aspect geometry — from a clean head-on to the traps examiners set: constrained by draught, Rule 17 in extremis, motor-sailing, fog, and multi-vessel traffic where the textbook turn for one contact puts you across another. Every visual scenario starts lookout-first: identify her lights before the radar unlocks. Then decide who's responsible, choose your action, and find out whether it actually kept you clear of everything — with the sub-rules cited when it didn't.
Pick a situation. It starts the way a real watch does — lights first: identify what you're looking at before the radar unlocks. Then decide who's responsible, choose your action, and see whether it actually keeps you clear — the same trial-and-error a real OOW does with a trial manoeuvre.