offshore safety - page 9

4.9 Man overboard (MOB)

Man Overboard (MOB) is fortunately a relatively rare occurrence, but chances are in your sailing career it is going to happen. It is a significant enough emergency that can be life threatening when it happens. This means that someone has fallen off the vessel and (hopefully) is bobbing in the water as the vessel sails away. This is a high-stress event, especially for the person in the water. Even at 5 knots of speed the distance between the MOB and the vessel increases rapidly. And given waves, it is very easy to lose sight of the person. Add to that cold water and you've got a very large chance that you might not be able to recover the person alive. MOB is serious.

Even in minor waves and swells, it is very easy to lose sight of the crew overboard. Thus it is important to appoint a crewmember that has no other job than simply continuously point to and keep an eye on the MOB at all times. 

Equipment

A person falling overboard requires: buoyancy to keep them afloat, to be seen and to be safely retrieved.

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Lifebuoy

This is a ring or horseshoe-shaped device thrown to a person in the water to provide buoyancy. Lifebuoys are often used on commercial boats, and regulations is some countries require them on leisure vessels. They stay in the sea where they are thrown but are large and heavy. Horseshoe lifebuoys are light and require a small drogue attached to stop them blowing across the water. Lifebuoys should be equipped with a drogue, light, retro-reflective tape and marked with the vessel's name. They can also carry a whistle or fluorescent dye to leave a coloured trail in the water. Retro-reflective tape wrapped in bands around a lifebuoy, greatly improves visibility at night. Lifebuoy lights require checking before night sailing because they are often unreliable. They should always be ready for quick deployment. Horseshoe lifebuoys are designed to be donned by pulling the horseshoe around the body. 

Danbuoys

A dabuoy marks a position in the water and increases the visible range to that position. It can pinpoint the exact MOB position or the nearest point from which to start your search. For example, at 12 knots a boat travels 0,5 mile in 2,5 minutes.   

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MOB actions

  • GPS/Plotter. The MOB button on the GPS inputs the position as a waypoint and displays the course and distance back. The MOB drifts away from the GPS position, but it is a point from which to start a search.

  • Crew. Use one or two crew to spot the MOB. If the boat cannot stop immediately, use the yacht's compass to get a rough bearing, or a bearing relative to the wind or waves. Binoculars may also help. 

  • Mayday. The definition of MAYDAY is, 'Grave and imminent danger to a vessels or person', so a MOB may fall into this category. Search and Rescue services prefer to be alerted immediately so they can make judgement call. Even if the yacht gets the MOB alongside, the hard part is often getting them back onboard. The victim will invariably require a medical check or help.

  • Recovery. Recovery of a MOB requires prior thought. The strenght and experience of crew, type of vessel and conditions will influence your decision. When someone falls into the water there are two specific need; that of the yacht, and that of the person in the water.The end result is the same, but whilst they are apart their requirements differ. The person in the water needs to float, be seen and get picked up. They may require buoyancy-fast. Be prepared to stop the boat, turn around, and sail close by to pass buoyancy. This buys you time to then ready the boat to pick them up. Consider throwing fenders or berth cushions if all other buoyancy has failed. 

  • The yacht's actions. The crew has a lot to do in a short time, but matters should not be made worse by being panicked into a manoeuvre that threatens to knock someone else overboard, or cripple the boat. Return to the person, quickly and safely.

Man/Crew Overboard procedure