The biggest issue with anyone in the water is getting hold of them. That is why Lifesaver type floating ropes should be standard in all lifejackets – see http://www.moblifesavers.com/. They allow you to use a boat hook to get hold of the MOB. Then in a 2 person situation a 6 : 1 handy billy clipped onto the end of the Lifesaver can allow the person to be hauled out of the water using say a spinnaker halyard. Ideally all MOBs should only be hauled out in a horizontal position because blood flow to the legs can cause heart failure if they are vertical.