Ship Handling and Maneuvering
What the exam tests
Ship Handling and Maneuvering tests control of the ship in confined and open water: pivot point, rudder and propeller effects, squat, interaction, anchoring, mooring and tug use. Answers should state the order and the expected ship response.
Core rules and concepts
- Pivot point is near one-quarter of length from the bow when making headway, and near the stern when going astern.
- A right-handed propeller gives transverse thrust: stern walks to starboard when going ahead, to port when going astern, in normal conditions.
- Squat increases in shallow water and with speed; it is greatest at the bow in a loaded ship and can cause bank suction.
- Bank effect: bow is repelled from the bank and stern is attracted, especially in a narrow channel.
- Reduce speed in a narrow channel to limit squat and interaction; avoid high-speed meeting.
- Anchoring: use scope about 5–7 times depth; veer under control and check the chain.
- Mooring: use spring lines to limit surge; keep personnel out of snap-back zones.
Worked example
A 200 m ship makes headway; pivot point is about 50 m from the bow. The rudder is about 150 m aft of the pivot, giving a long lever. With full ahead and hard a starboard, the stern swings to port and the bow to starboard. In shallow water, rule of thumb squat ≈ Cb × V²/100: for Cb 0.8 and 10 kn, squat ≈ 0.8 m. Reduce speed before entering a dredged channel.
Traps
Assuming the pivot point is at the bow; forgetting transverse thrust when leaving a berth; ignoring squat in shallow water; using too little anchor scope; and giving tug orders without an agreed communication protocol.
Key points: pivot point; transverse thrust; squat; bank effect; anchor scope; tug communication.