I often read of a "last chance" line trailed behind the boat. The line described was most often tragically short. Sail magazine described one only 15 feet long. If you fall in head first, angled away from the boat, and the boat is moving at a 5-7 knots, 75 feet is the minimum required distance based on my testing in summer weather. You better have 150 feet if you want any hope of finding it in adverse conditions. They also think that they can either make the boat stop by tripping the rudder (the boat may just tack away and keep sailing--you did not take the time to trim it for heaving to, or bring the rudder back up) or simply haul themselves back to the boat (impossible over about 3 knots). The other thing they always have in common is that they have not TESTED their theory by jumping in. Man, if you have not tested it, don't even report it as an idea. Someone might believe you.
I imagined myself hanging on the said rope at 7 knots, waiting to get tired and let go. I've been towed as a water skier, so it was not hard to imagine. I also tested the speed At which I could hang on to a 3/18-inch floating line, and the speed at which I imagined I could (dressed in foul weather gear and a PFD) haul myself back to the boat. It becomes clear with in moments that what you will pray for is for the boat to STOP. Nothing else. You would give anything to make the boat stop, like dropping an anchor (see where we are going with this?). And as it turns out, that isn't really so hard, at least not with smaller boats.
Basically, it is a parachute with the floating line as the rip cord. You don't need to pull hard, just enough to pull the gear from the storage bag on the deck. The chute and rope stream out, and about 10 seconds later, the chute fills, creating a whole lot of drag. A nylon climbing rope provides the energy absorption, bring the boat to a slow stop (about 1-2 knots, even with the engine at full throttle). All that remains is to pull yourself to the boat, hand over hand, which is not very difficult with the boat nearly dead in the water.
Yup, I tested it repeatedly, sometimes powering, sometimes under sail, upwind and down. It didn't matter. The success rate was 100%. All I asked of the crew was to keep filming.A seemingly crazy idea that simply works.
I'm not at all surprised. For years, in testing, I would drop drogues and sea anchors off the transom at full speed to create maximum impact force, often using non-stretch rodes and larger boats. Although the strain could be high, nothing ever failed.
Staying on the boat is better. Stay low and clip-in when it gets rough.
[Details are in Practical Sailor Magazine. Obviously, the engineering varies with the weight and speed potential of the boat.]