Standard Manoeuvres & Ship Handling
Turning circle
Advance: distance travelled along the original course from the moment the rudder is put over. Transfer: distance perpendicular to the original course. Tactical diameter: transfer at 180° of heading change.
A loaded VLCC may need 3–5 ship lengths of advance; a ferry far less. Know your own ship's manoeuvring booklet and the wheelhouse poster.
Speed drops markedly in a hard-over turn — typically 25–40% loss for a large ship.
Crash stop
Head reach in a crash stop from full sea speed can be 8–15 ship lengths for a large vessel, and takes several minutes.
A turn generally stops a vessel in less distance than an astern movement, and keeps steerage. Consider a hard turn before a crash stop.
Single screw vs twin screw
A right-hand fixed-pitch single screw going astern walks the stern to port and swings the bow to starboard — plan berthing port side to where possible.
Transverse thrust is strongest at the initial kick astern and at low speed.
Twin screws allow twisting: one ahead, one astern, turning the vessel almost in her own length, especially with a bow thruster.
Man overboard
Immediate actions: hard over to the side of the casualty, release lifebuoy with light and smoke, sound three prolonged blasts, mark the position on GPS/ECDIS, post lookouts, inform the Master.
Williamson turn: rudder hard over to the side of the casualty; at 60° from original heading, shift the rudder hard over the other way; steady on reciprocal course. Best in reduced visibility or when the time of the fall is uncertain — it returns the ship onto her own track.
Anderson (single) turn: fastest for an immediately witnessed loss in good visibility, but requires precise handling and an approach that is not on the original track.
Scharnow turn: saves time and fuel but must not be used when the casualty position is close astern, as it does not pass the original position early.
Emergency anchoring
Use when drifting into danger with engine or steering failure and depth permits. Walk out the anchor under power rather than letting go in deep water or with headway.
Headway should be minimal — dropping with way on risks parting the cable or damaging the windlass. Consider both anchors and short scope to slow the vessel.
End-of-module quiz
1. Tactical diameter is the transfer measured at:
2. The Williamson turn is preferred when:
3. A right-hand fixed-pitch single screw going astern will typically:
4. Compared with a crash astern from full sea speed, a hard-over turn generally:
5. When anchoring in an emergency you should: