Narrow Channels & Traffic Separation
Where the open sea ends and ship traffic concentrates — narrow channels, separation schemes and the busiest straits in the world. Get this block wrong and a 200,000-ton container ship becomes the last thing you ever see.
Built for: skippers crossing Dover Strait, Bosphorus, Strait of Gibraltar, Singapore Strait and the Solent; Officer of the Watch trainees handling commercial transits; charter skippers approaching Adriatic and Aegean port entrances; commercial deck officers preparing for re-validation.
Why this module exists
Rules 9 and 10 are where small-craft skippers most often clash — culturally and legally — with commercial shipping. A yacht skipper at the wheel of a 38-foot cruiser may believe sail-vs-power gives them right of way; in a narrow channel or TSS, that belief can be fatal. Rule 9 and Rule 10 override the give-way / stand-on logic of Rules 12–18 in their respective waters.
The scenarios are drawn on the radar and the chart: a traffic separation scheme with its lanes, or a marked channel, and the ships following them, each one an AIS target with her course, speed, CPA and TCPA. The debrief records whether you kept to your side of the channel, joined the lane at a shallow angle or crossed it at right angles, and kept clear of the ships in it. In Free Mode the real Daugava fairway at Riga adds the port's speed limits and no-overtaking zones.
The simulator scenarios
- TSS — Cross at Right Angles — the lanes run north–south on the radar: cross on a heading as nearly at right angles to the traffic flow as practicable and do not impede the ships following the lane (Rule 10(c), 10(j)). Free demo scenario.
- Narrow Channel — Keep Starboard — transit a channel marked on the radar, keeping as near its starboard limit as is safe and practicable (Rule 9(a)).
- Narrow Channel Overtaking — overtake a slower vessel inside the channel, stay between its edges and pass at a safe distance (Rule 9(e)).
- TSS — Joining at a Shallow Angle — join the northbound lane at as small an angle to the traffic flow as practicable (Rule 10(b)(ii)).
- Free Mode in the port of Riga — the Daugava fairway and its ships: the simulator calls out the port's speed limits and no-overtaking zones, and warns you if you cross close ahead of a ship.
- Scenario briefings — each scenario has its own page with the situation, the rule and the recommended action: all 54 briefings.
Common mistakes
- Crossing the TSS at an oblique angle — "saving time" by cutting at 30°. The simulator marks any heading more than 10° off the right angle as a Rule 10(c) violation, and a pass closer than 0.5 NM to a ship in the lane as impeding her (Rule 10(j)).
- Forgetting that Rule 9 trumps sailing-vessel rights — a sailboat in a narrow channel does not have priority over a commercial ship confined to it.
- Anchoring in a narrow channel — Rule 9(g) prohibits this except in emergency.
- Fishing in the lane — Rule 10(i): vessels engaged in fishing shall not impede the passage of any vessel following a traffic lane.
- Joining the lane from the side — Rule 10(b)(ii) requires joining or leaving at the termination, or at as small an angle as practicable.
📸 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 9(a) — Narrow channel — keep starboard. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.
Bridge-simulator scene under COLREG Rule 9(e) — Narrow channel — overtaking. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.
Bridge-simulator scene under COLREG Rule 10(c) — TSS — crossing at right angles. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.
Bridge-simulator scene under COLREG Rule 10(b)(ii) — TSS — joining at a shallow angle. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.
