COLREG / ARPA / AIS Bridge Rule 10(b)(ii) 🔒 Course / Premium

TSS — Joining at a Shallow Angle (Rule 10(b)(ii))

You are joining the northbound TSS lane (right lane). Rule 10(b)(ii): a vessel joining a lane shall do so at as SMALL AN ANGLE to the general direction...

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Scenario briefing

You are joining the northbound TSS lane (right lane). Rule 10(b)(ii): a vessel joining a lane shall do so at as SMALL AN ANGLE to the general direction of traffic flow as practicable. Enter the lane on a heading between 000° and 020° (shallow angle), then click EVALUATE.

Applicable COLREG rule(s)

Rule 10(b)(ii) — referenced in this scenario. Practising this scenario reinforces correct application under realistic time pressure.

📸 Bridge simulator scene

Captured directly from the SkipperCheck COLREG bridge simulator at scenario T = 0 — the moment the encounter begins.

SkipperCheck bridge simulator — COLREG Rule 10(b)(ii) — TSS — joining at a shallow angle — radar PPI with AIS targets — Bridge-simulator scene under COLREG Rule 10(b)(ii) — TSS — joining at a shallow angle. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.

Key teaching points

Join at as small an angle to the general direction of traffic flow as practicable (Rule 10(b)(ii)).
In practice this means entering at less than 20°, then merging onto the lane heading.
Until fully in the lane, you are subject to Rule 10(j) — you must not impede vessels already following it.
Use AIS to identify lane traffic 5+ NM ahead; this is not a "wait at the edge and squeeze in" situation.

Common mistakes to avoid

Joining at 60–90° "to clear the inshore traffic zone fast". Rule 10(b)(ii) explicitly requires a shallow angle.
Joining ahead of lane traffic on a converging course — Rule 10(j) applies until you are settled in the lane.

Why it matters

Joining a lane is where right-of-way confusion arises — you are about to become a "vessel following the lane" but until you do, you are a crossing vessel that must not impede. The shallow-angle approach is the rule's way of resolving that ambiguity.

Exam relevance

TSS join/leave technique is examined in RYA Yachtmaster Offshore and STCW OOW orals, often paired with a chartwork plot of the approach.

Related scenarios

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