trough and hauled again during the next rise, if this is possible. A fitter casualty may climb a ladder more or less unaided, although the dangers of approaching the stern of the boat in a rough sea should be considered if that is where the only useful ladder is. A fitter casualty may be able to get a foot onto a simple loop of rope and lift themselves to the rail. A hypothermic, injured or unconscious victim may be quite incapable of helping themselves. In this case netting, slings, an inflatable dinghy or liferaft may be employed, with or without the additional assistance of a 4:1 or better tackle. Such a tackle may be fashioned from a mainsheet, a boom vang (kicking strap), or may be purpose-made for the job and stored in case needed. The yacht's winches may also be of assistance. Technology Technology can also be used to assist in the retrieval of people who fall overboard. Many GPS chart plotters designed for marine use have a Man Overboard button (MOB). This button is pushed as soon as a Man Overboard alarm is raised, causing the plotter to record the latest known position of the person overboard. This allows the boat to be easily returned to the fallen crew member even if visual contact is lost. Several manufacturers make man overboard alarms which can automatically detect a man overboard incident. The hardware consists of individual units worn by each crew member, and a base unit. Some systems are water activated: when an individual unit comes in contact with water, it sends a signal to the base unit, which sounds the man overboard alarm. Other automatic detection systems rely on a constant radio signal being transmitted between an individual unit and the base unit; passing outside the transmission range of the individual unit and/or falling into the water cause the radio signal to degrade severely, which makes the base unit sound the man overboard alarm. Some manufacturers' hardware integrates with other systems on the boat; for example, it may activate a throttle kill switch or control the autopilot to return to the point of the downed member. In wartime In wartime, especially in waters where enemy submarines may be present or where a warship cannot otherwise be safely stopped, a man overboard may unfortunately be abandoned rather than endanger the rest of the crew by rescuing him. An example