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Chief Mate CoC study materials
Chief Mate CoC study resources

Chief Mate CoC: Watchkeeping and Collision Regulations

Chief Mate CoC · Work through your exam, one topic at a time.

All guide sections

Watchkeeping and Collision Regulations

Watchkeeping and Collision Regulations is the highest-frequency area in chief mate papers: the COLREGs applied to real geometry, plus the STCW standard for watch composition, rest and fitness for duty.

Rules of the road - the working sequence

  • Rule 5: look-out by sight and hearing and by all available means, including radar.
  • Rule 6: safe speed - visibility, traffic density, manoeuvrability, background light, sea state, draught and stopping distance.
  • Rule 7: risk of collision exists with a steady bearing and decreasing range; if in doubt, assume it does; do not rely on scanty radar information.
  • Rule 8: action must be positive, made in good time, substantial, and result in passing at a safe distance.
  • Rule 9: narrow channel - keep as near the starboard outer limit as is safe and practicable.
  • Rule 10: traffic separation schemes - cross on a heading as nearly as practicable at right angles.
  • Rule 13: the overtaking vessel keeps out of the way, and this overrides crossing.
  • Rules 14–18: head-on, both alter to starboard; crossing, the vessel with the other on her starboard side gives way; the stand-on vessel holds course and speed but may act under Rule 17 when collision cannot be avoided by the give-way vessel alone.
  • Rule 19: restricted visibility - there is no stand-on vessel; reduce to minimum steerage way if a close-quarters situation develops.

STCW watchkeeping

Minimum 10 hours' rest in any 24 and 77 hours in any 7 days, including at least 6 continuous hours, with records signed. Alcohol limit: 0.05 per cent BAC or 0.25 mg/l breath, lower under many national rules.

Worked example

You are in a power-driven vessel making 15 knots; a radar target bears 045° relative at 7 nm, steady bearing, range falling 1 nm every 4 minutes. The other vessel is on your starboard side, so you are the give-way vessel under Rule 15. Alter course substantially to starboard to pass astern of her - never to port across her bow, and never with a token 10° change. Replot after the alteration to confirm the bearing is opening.

Traps

Waiting for the stand-on vessel to act; alterations too small to be readily apparent on radar; using AIS instead of radar and visual observation; assuming Rule 15 applies in fog; and forgetting that Rule 13 overtakes Rule 15.