Collision Regulations and Safe Navigation
Rules that decide the case
This domain tests application of COLREGS and safe navigation, especially risk of collision, action by give-way and stand-on vessels, and conduct in restricted visibility.
- Rule 5: maintain a proper lookout by sight and hearing and all available means.
- Rule 7: use compass bearings and radar plotting; a steady bearing with decreasing range means risk.
- Rule 15: in a crossing situation, the power-driven vessel with the other on her starboard side gives way and avoids crossing ahead.
- Rule 16: give-way action must be early and substantial; Rule 17 stand-on vessel keeps course and speed but must act when collision cannot be avoided by the give-way vessel alone.
- Rule 19: in restricted visibility there is no stand-on vessel; reduce speed and act on radar information.
Worked example
Power-driven vessel A is on 000°T at 15 knots. A observes power-driven vessel B bearing 045° relative, steady, range falling from 6 nm to 4 nm. B is on A's starboard bow, so this is a crossing situation and A gives way. A should alter course to starboard and pass astern of B, not alter to port or attempt to cross ahead. With 6 nm range and about 12 knots closing speed, initial TCPA is about 30 minutes, enough for early substantial action.
Traps
Altering to port for a vessel on the starboard side. Treating the stand-on vessel as having no duty. Using whistle signals without understanding manoeuvring signals. Relying on AIS alone and not confirming risk by radar or visual bearings.