COLREG / ARPA / AIS Bridge Rule 10(c) ✓ Free demo

TSS — Crossing at Right Angles (Rule 10(c))

You must cross a Traffic Separation Scheme whose lanes run NS (shown on the PPI).

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Scenario briefing

You must cross a Traffic Separation Scheme whose lanes run NS (shown on the PPI). Rule 10(c): a vessel crossing traffic lanes shall do so on a heading as NEARLY AT RIGHT ANGLES to the general direction of traffic flow as practicable. Rule 10(j): do NOT impede the safe passage of vessels following the lane. Cross with heading 080°100° (east-bound) AND keep CPA 0.5 NM on any lane-traffic vessel if a risk of collision develops, the scenario fails. Click EVALUATE when you have crossed both lanes.

Applicable COLREG rule(s)

Rule 10(c) — 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(c) — TSS — crossing at right angles — radar PPI with AIS targets — Bridge-simulator scene under COLREG Rule 10(c) — TSS — crossing at right angles. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.

Key teaching points

Cross on a heading as nearly at RIGHT ANGLES to the general direction of traffic flow as practicable (Rule 10(c)).
Heading, not course made good — current/leeway are irrelevant for the rule. Aim the ship across the lane.
A crossing vessel shall not impede the safe passage of a vessel following the lane (Rule 10(j)).
Maintain visual and radar watch in BOTH lanes throughout the crossing — traffic in the far lane closes faster than you expect.

Common mistakes to avoid

Adjusting heading to compensate for cross-tide so that course made good is 090°. The rule talks about heading.
Crossing under sail and tacking inside the lane. Rule 10(j) makes you a vessel that must not impede — tacking obstructs.

Why it matters

TSS crossings are the highest-traffic-density encounters most yachts ever experience — the Dover Strait alone sees 400+ commercial transits a day. The rule is precise about heading and impedance because misapplication routinely causes near-miss reports to MCA and equivalents.

Exam relevance

TSS crossing is a near-universal question in RYA Yachtmaster Coastal/Offshore and SRC orals — examiners verify the candidate distinguishes heading from course made good.

Related scenarios

About SkipperCheck simulators

SkipperCheck offers two browser-based maritime training simulators:

ARPA · AIS · COLREG Bridge Simulator — 54 scenarios covering Rules 2, 5–10, 12–19, 23–30, 34 and 35.
VHF SRC Radio Simulator — 15 scenarios: voice Mayday, DSC distress, Mayday Relay, Pan-Pan, Sécurité, routine.

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