Fundamentals — Rules 2, 5, 6, 7, 8
The five rules every mariner must apply at all times — in fog or in sunshine, at anchor or at full speed. These foundations underpin every other COLREG decision; without them, the rest of the regulations cannot be sensibly applied.
Built for: anyone starting their COLREGs preparation — Day Skipper, ICC, Yachtmaster Coastal, RYA, STCW Officer of the Watch and maritime academy cadets. Even seasoned skippers refresh this block before a charter season.
What this module covers
Most of the COLREGs tell you what to do in specific encounters — head-on, crossing, overtaking. The fundamentals tell you the state of mind you must maintain so those rules can be applied at all. They are about perception, judgement and timing, not about who has right of way.
The simulator scenarios in this block are deliberately simple in geometry — usually two vessels in open water — so you can focus on building the habits these rules demand: scanning the horizon, calling CPA values out loud, choosing a manoeuvre that is observable rather than tentative, and committing to it early.
How the simulator teaches it
Each Fundamentals scenario opens in open water with one to three target vessels. You see the situation as a real OOW would — through the bridge windows, on AIS overlay, and on radar with ARPA tracks. Your job is to:
- Scan 360° at the start (look-out — most students forget the stern in the first run).
- Identify targets on AIS by name, type and CPA/TCPA. Read the navigation status — fishing, restricted, anchored.
- Assess risk: is bearing constant? Is CPA below your safety margin? At what range will TCPA expire?
- Decide and execute a manoeuvre that is early, large and obvious. The simulator measures whether your alteration is at least 30° (Rule 8 "readily apparent") and whether you committed in ample time.
- Verify on radar that the new vector clears all targets, then resume course.
The free demo scenario "Familiarization" lets you walk through these five steps with a single approaching power-driven target in good visibility — a perfect first run.
Common mistakes the simulator catches
- Tentative manoeuvres — altering 5–10°. The simulator flags this and shows how the target's CPA on radar barely moves.
- Late action — relying on the give-way vessel doing the right thing. Rule 8(a) requires action in ample time; "ample" depends on speed and visibility, not on the other ship.
- Speed-only solutions in restricted waters — in confined or busy water, course alteration is often safer than just slowing down.
- Tunnel vision on AIS — yachts under 20 m are not required to carry AIS-A. A target invisible on AIS may still be on radar (or directly ahead). Rule 5 says all means, not just AIS.
- Forgetting Rule 2 — rules don't excuse you from doing the seaman-like thing if obeying them creates greater danger.
📸 Bridge-simulator scenes from this module
Each row shows one scenario: the law text + scenario name on the left, the matching simulator-rendered radar/AIS scene on the right. Captured at scenario T = 0 — the moment the encounter begins. Click any image to open full size.
Bridge-simulator scene under COLREG Rule 7 — CPA / TCPA risk-of-collision recognition. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.
Bridge-simulator scene under COLREG Rule 2, 5–8 — Familiarisation — radar PPI with AIS targets. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.
Bridge-simulator scene under COLREG Rule 5 — Lookout — prioritising risks. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.
Bridge-simulator scene under COLREG Rule 5–8 — Multi-target encounter — ARPA tracking. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.
Bridge-simulator scene under COLREG Rule 2 — Departure to avoid immediate danger. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.
Bridge-simulator scene under COLREG Rule 8 — Action to avoid collision. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.
Bridge-simulator scene under COLREG Rule 6 — Safe speed in fog. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.
