Sailing alone: sleep, check-ins and staying found
Two problems follow every solo sailor. Nobody watches while you sleep, and nobody turns back if you fall in. How people who sail alone keep both of them small.
In this piece
Single-handed sailing comes with two problems that no gadget removes. While you sleep, nobody is keeping a lookout. If you go over the side, nobody turns the boat round. Most of solo sailing safety is the work of making those two gaps small: sleeping in short, timed naps where the traffic is thin, letting AIS and radar watch while you are below, staying clipped to the boat every minute you are on deck, and carrying the beacons that tell somebody where you are.
Sailing alone will never be as safe as sailing with a crew, and the people who do a lot of it do not pretend otherwise.
The lookout rule, and what solo sailors actually do
Rule 5 of the collision regulations, the COLREGs, says every vessel shall “at all times maintain a proper look-out by sight and hearing”, and by every other means available. There is no exception for a crew of one. A boat whose only person aboard is asleep below is not keeping a proper lookout, whatever electronics she carries, and after a collision nobody will argue that she was.
Single-handers live with that by choosing where they sleep. Near the coast, in and around shipping lanes and traffic separation schemes, off headlands where traffic bunches up and over fishing grounds, they stay awake. They plan coastal passages so the busy stretches come in daylight and they arrive at them rested, and a single night at sea is often done on catnaps. Real sleep happens in open water, away from the routes the ships use, in short stretches with a timer. On a crewed boat the same problem is solved with a watch rota; alone, the timer is the rota.
How long can you sleep when sailing solo? The 20 minute sum
The figure you hear most often is twenty minutes. It comes from two numbers: how far away you can see a ship, and how fast she is moving.
Start with the horizon. The distance to the sea horizon in nautical miles is roughly 2.1 times the square root of your height of eye in metres. Sitting in a yacht’s cockpit your eye is about 2.5 m above the water, so your horizon is about 3.3 nm away. Ships show up further out than that because they stand tall: a container ship’s bridge is 30 m or more above the sea, and in clear daylight you can pick up her upper works at 10 nm or more. At night you are looking for lights, and the rules only require the masthead light of a ship of 50 m or more to be visible at 6 nm. Many are brighter. Plan on six.
Now the speed. A ship at 20 knots covers a mile every three minutes.
| Ship’s speed | 1 nm takes | 6 nm takes | 10 nm takes |
|---|---|---|---|
| 12 kn, a slow cargo ship | 5 min | 30 min | 50 min |
| 20 kn, a container ship | 3 min | 18 min | 30 min |
| 30 kn, a fast ferry | 2 min | 12 min | 20 min |
Then add your own speed if the two of you are heading toward each other. You at 6 knots and a ship at 20 close at 26 knots, and 6 nm goes in under 14 minutes.
If you looked properly all round before lying down and saw nothing, any ship out there was at least 6 nm off. At 20 knots she needs 18 minutes to reach you, at 12 knots half an hour, and a fast ferry, or a ship you are sailing toward, less again. By these sums the classic twenty minutes is already on the long side. Treat it as an upper limit for good visibility and ordinary traffic. Haze, rain, or a big sea hiding lights in the troughs all shorten it, and in fog none of it holds.
Run the sums the other way and they get less comfortable. A sailing yacht under 12 m only has to show sidelights visible at 1 nm. At 20 knots that gives the officer on the bridge three minutes of warning, and only if they happen to be looking your way. Assume nobody has seen you until AIS or the radio says otherwise.
When the timer goes, stand up, turn all the way round slowly, and check the patch of sea under the genoa, which is where ships hide from yachts. Give your eyes a minute after the cabin before you decide the horizon is empty.
Let the electronics watch while you are below
An AIS transponder does two jobs: it shows you the ships, and it shows you to them. For sleeping, the part that matters is the alarm. Set a closest point of approach (CPA) and a time to it (TCPA), and the plotter or the AIS unit sounds off when any target is predicted to come inside them. In open water, 2 nm and 30 minutes is a reasonable place to start. If it wakes you every ten minutes, you are probably somewhere too busy to be asleep.
Then make sure you can hear it from the bunk. A beeper in the cockpit that is inaudible with the washboards in is worse than none, because it makes you feel watched. Some AIS units have an output for an external buzzer, and a tablet showing the AIS feed can sit beside your head.
AIS only sees boats that transmit. Small fishing boats, plenty of yachts and some naval and government vessels do not show up at all. Radar does, where you have it. Set a guard zone, a ring around the boat, and it alarms when anything enters. It will also alarm for rain squalls and, in a big sea, for wave tops, so set the sensitivity in daylight when you can see what it is reacting to.
None of this is a lookout in the sense Rule 5 means. It shortens the time you are blind.
Staying on the boat
With crew, going overboard is an emergency. Alone, it is very often the end, because the boat sails on without you. So the gear has one purpose, which is to keep you on deck. A tether that stops you on deck has done its job. A tether that catches you in the water may tow you alongside at six knots, face down, and that is no rescue.
Run jacklines from the cockpit to the bow on both sides, or down the middle of the deck if your boat allows it, and lead them inboard so that with the tether at full stretch you fetch up against the guardwires and not over them. Flat webbing is better than wire or rope, which roll under a foot. Fit a strong point by the companionway so you can clip on before your head is out of the hatch, and unclip last when you go below. Use the short leg of a double tether for working on deck and the long one only when you need the reach. Solo, clipping on is not a weather decision. It applies in the cockpit, in daylight, on a calm night, every time.
Plenty of people have gone over the side doing something ordinary on a quiet night, including relieving themselves over the rail. Use a bucket.
A way back aboard that you can reach from the water
Suppose it has happened anyway and you are in the water next to the boat, perhaps because she has rounded up or you were hove to. Can you get back on? Most bathing ladders fold up on the transom where a swimmer cannot reach them. Fit one that can be released from the water, with a line or a catch that hangs down where your hand will find it, or keep a rope ladder in a bag on the pushpit with a pull cord that drops it. Then try it in a calm anchorage, with a friend watching from the dinghy, wearing the clothes and the life jacket you would wear at sea. Wet clothes and an inflated life jacket turn a short climb into a hard one.
Some solo sailors trail a long floating line astern, sometimes rigged so that a pull on it knocks out the self-steering. At more than two or three knots, holding on to a line in the water is very hard. Count it as a last chance, nothing more.
Beacons: who finds you, and who sees you
A personal locator beacon (PLB) belongs on the life jacket you actually wear, in its pocket or clipped to the harness, never in a grab bag below. Registered to you, it sends a 406 MHz alert through the Cospas-Sarsat satellites to the rescue coordination centres, with a GPS position on most current models. You have to switch it on yourself and get the antenna clear of the water, which is harder at night with cold hands than it sounds. Read its instructions now, so you know the sequence before you need it.
An AIS MOB beacon does a different job. It puts a man overboard target on the AIS screens of vessels within VHF range, typically a few miles, and many fit inside the life jacket and switch on by themselves when it inflates. Some also send a DSC alert. On a crewed boat that target appears on your own plotter. Solo, your own boat is sailing away from you, so the ships nearby are the ones who need to see it. Carry both if you can: the PLB brings the rescue services, and the AIS beacon tells the ship two miles away to start looking.
For the boat itself, a registered EPIRB is the offshore standard, and a satellite messenger gives you two-way text and a tracking page beyond mobile range. A beacon tells the rescuers where you are. A float plan left with someone ashore tells them who you are, what the boat looks like and when to start worrying.
Fatigue and food
Tiredness makes every other risk on this page worse, and it arrives before you notice it. Judgement goes first: you make simple jobs complicated, put off the reef you know you need, read the same number on the plotter twice. So start rested. Leaving after a week of boat jobs and a farewell dinner means starting the passage already in debt. On passage, sleep whenever the conditions let you, including in daylight when the horizon is clear.
Reef at dusk, before you need to, so the boat stays easy to handle at 3 am when you are at your slowest. Cook before you leave: a pot of stew or soup that only needs heating, sandwiches wrapped for the first night, a box of snacks within reach of the helm, a flask of hot water. Drink plenty of water, because dehydration and cold both feel like tiredness. If you take seasickness tablets, find out on a day sail whether yours make you drowsy. And no alcohol at sea.
After a few days of broken sleep, single-handers often report seeing lights and hearing voices that are not there. That is sleep debt talking, and the only cure is sleep.
The timer habit
Every nap starts and ends the same way. Look all round, check the AIS and the radar, the course and the sails, set the timer, lie down. When it goes, get up and do all of it again before you think about the next nap. Put the timer where you have to stand up to stop it, because a timer you can silence from the bunk is a timer you will silence from the bunk. Twenty minutes is the upper limit. Near the coast or in any traffic, make it ten or fifteen, or stay up.
Be clear about what that alert can do. The push to a paired phone needs a data connection on the phone aboard, so it works along the coast while you have mobile signal and stops working on the open sea. That makes I’m OK a coastal tool. Offshore, the things that bring help are the EPIRB, the PLB on your life jacket, a satellite messenger and a Mayday on the VHF, and no app replaces any of them.
One job for your next quiet anchorage: put on your life jacket, go in off the transom with a friend in the dinghy, and find out whether you can get back aboard without help. If you cannot, that is the next thing to fix on the boat.