What is the man overboard (MOB) procedure on a ship?

Man overboard is one of the most time critical emergencies at sea, because in cold water survival is measured in minutes rather than hours, and everything about the drilled response is built around not losing sight of the casualty and getting the ship back to them as fast as possible. The first person to see someone go over the side shouts man overboard to raise the alarm immediately, and without waiting for permission throws a lifebuoy fitted with a self igniting light and a smoke float toward the casualty, both to give buoyancy and to mark the position on the water. One person is detailed purely to point continuously at the person in the water, because in any kind of sea state a head quickly disappears from view and is very hard to relocate, and the bridge is informed at once.

The officer of the watch takes immediate ship handling action. At close quarters the helm is often put hard over toward the side the person fell from, to swing the stern and propeller away from them and reduce the risk of the person being struck, and the ship is brought around using a recognized recovery maneuver: the Williamson turn, which reliably returns the ship down its own reciprocal track and suits low visibility or when the casualty was not seen going over, the Anderson turn, which is fastest in calm conditions with a single engine ship, or the Scharnov turn, used once well clear of the casualty. Engines are made ready for maneuvering, the position is marked immediately on GPS and ECDIS using the dedicated MOB function, the general alarm may be sounded, the master is called, the crew mustered, and a rescue boat prepared for launching, all in parallel with the ship handling.

If the casualty is not recovered quickly, the response shifts to a formal search: extra lookouts are posted, a DSC distress alert and an urgency broadcast may be made to bring nearby vessels into the search, and the bridge team runs a recognized search pattern such as an expanding square or sector search from the last known or datum position, factoring in wind and current drift. Cold water shock and hypothermia are constant threats even in temperate water, so speed matters as much once a search begins as it did in the first thirty seconds.

Recovery itself needs care: a rescue boat, a pilot ladder, a purpose built recovery sling or net, or in calm conditions maneuvering the ship itself to bring the casualty alongside a low freeboard point, followed immediately by first aid for cold shock, injury and hypothermia. Because every second and every decision matters and there is no time to think it through from scratch, regular, realistic man overboard drills covering both the ship handling and the recovery equipment are what actually make the difference between a rescue and a loss.