This is big trouble
Recent tests carried out by a number of equipment manufacturers and reported in the sailing press show how hard it is to deal with crew over board situations. This one is typical in that there is inadequate crew.1. Hit the MOB bottom on your GPS or chartplotter if you have one. There are likely waves of 2 to 3 feet, and you have no spotter, so finding your buddy could become a problem.2. throw whatever you have on the stern rail towards him. Lifering, throw bag, man over board pole, whatever, you will help mark the spot and maybe provide some buoyancy (assuming he is still conscious).3. this is no time to try a figure 8 stop or something fancy you learned in sailing school. With no one to help you handle the boat in a good breeze and no spotter, you can't afford to go far. Therefore, immediately head straight into the wind to kill your speed. You are likely going about 5 knots, or 10 feet/second. You are now 20 seconds into the emergency, and have gone 200 feet. By the time you are stopped and in irons, probably you have gone another 100 feet at least.4. furl your headsail (or drop it). Otherwise, it will block your vision as you head back. Turn on the engine. You are not going to chop anyone up at this distance. Now you can fall off to a beam reach on the opposite tack and spot the MOB, hopefully by eye, if not, using the mark you created on the GPS. If you have a cockpit VHF, now is the time to send a PAN PAN. 5. You want to approach on the lee side of the cob and turn back into the wind below him, coming to a stop beside and to windward. With the help of the engine and the mainsail, you should be able to do this pretty easily. As you turn to windward, the engine must be taken out of gear and turned off; now you really could chop him to pieces.6. Again assuming your buddy is awake, you should be able to attach him to the boat with a mooring line, a jib sheet or something. If not awake, your best hope is to hook him with a boat hook and get him close enough to the transom to tie something to him. You are obviously not going to jump into the water.7. Getting someone who weights alot more than you back on board will now be the big challenge. If the water is fairly flat, you might get lucky and be able to use the swim ladder (maybe you even have an ice cream scoop stern, which will help). Otherwise, you will probably have to bring a halyard back, and crank like crazy on your primary winch.8. Most fatalities in these situations involve trouble in getting the cob back on board. Cold water will weaken the cob very fast; he may have been injured by the collision with the boat; his wet clothes add to the weight. You can only hope to succeed if you use the mechanical advantage given to you by the winch and the height advantage of the mast.9. This is where you may need help from someone else. It may be impossible for you to get the cob on board by yourself. That's why you got on the VHF earlier (if not, now is the time). No one is going to die of hypothermia in the time it should take another boat to get to you (this is a day sail).10. All the tests reported show that this scenario is much harder to resolve in real life than on paper. Once your buddy has gone over the rail in this scenario, I think there is at least a 25% chance of a fatality. That's why we should wear our PFD's and hold on tight at the pointy end.