Every passage begins twice. Once on the water, and once on paper, the night before, when somebody sits down with the distance and a pencil and works out when the boat will arrive. The paper version is always tidier. Ours said 124 nautical miles, an average of five and a half knots, twenty-two hours and thirty-three minutes under way. Leave at ten in the morning, tie up at half past eight the next day, in time for a late breakfast ashore. It was a good plan. The sea read it politely and then did something else.
I should say what my job aboard was. There were three of us on a friend’s thirty four footer, and the other two can sail. I can count. On a boat, that turns out to be a real job because a passage is a long string of small sums while wearing oilskins: miles against knots, hours against fuel and water quantities, watches against sleep. This is the story of those sums, and of the moment, a little after midnight, when they quietly told us the truth about our arrival while the plan was still pretending otherwise.
The Passage
The first leg flattered us. For the initial sixty miles the boat averaged 6.1 knots over the ground, helped for four of those hours by a favourable current of 1.2 knots that handed us 4.8 miles we did not have to sail for. Sixty miles at 6.1 knots is nine hours and fifty minutes, so by eight in the evening we were more than an hour ahead of the paper plan, eating well and feeling clever. Anyone who has made a passage knows that feeling, and knows what it is worth. An average is a promise the wind never signed. Ours held exactly as long as the breeze did.
Then the wind eased off, the way it does after dark along that coast, and the knot meter began its slow retreat: five knots, four and a half, and by late evening a steady 3.9. Nothing was wrong. The sails were trimmed, the boat was happy, dinner had been good. Only the numbers had changed their minds. There were sixty four miles still to go, and sixty four miles at 3.9 knots is sixteen hours and twenty five minutes of going, which no amount of optimism at the chart table could argue down.
The Arithmetic
This is where the counting earns its keep, and it is worth doing slowly, because the temptation at midnight is to average everything and hope. Add the two legs honestly: nine hours fifty minutes gone, sixteen hours twenty five still to come, twenty six hours and fifteen minutes for the whole passage. I keep a free time calculator [1] bookmarked for exactly this kind of adding up – the hours and minutes of legs and watches – because tired brains drop minutes the way pockets drop coins. At midnight itself the sum was cleaner and harder to dodge. Fourteen hours out, we had covered a shade over 76 miles. Just under 48 miles remained. At 3.9 knots that is twelve hours and fifteen minutes more, which put our arrival at a quarter past twelve the next day, not half past eight in the morning. The plan had not collapsed. It had thinned, hour by hour, and the sums noticed long before we wanted to.
The watches, at least, behaved. Darkness on that passage ran from nine at night to six in the morning, nine hours of it, and three crew dividing nine hours by three hour watches gives each person exactly one full night watch and two honest stretches of sleep. It is the fairest sum on any boat and the one nobody argues with. I took the middle watch, which is how I came to be awake, alone with the log and the pencil, when the midnight arithmetic delivered its verdict.
The quiet budgets behaved too, and counting them was its own comfort. We motored six and a half hours in total, in the calm patches and at both ends, at a burn of 2.8 litres of fuel an hour. That is 18.2 litres out of a ninety litre tank, about a fifth gone, on a tank that holds thirty two hours of motoring at that rate. Water was the same story told larger. That tank carries 120 litres. At five litres per person per day for three crew, that is eight days of water. Over the whole passage, twenty six hours of it, we used eleven litres, about nine percent of what we carried. People talk about reserves as dead weight. At two in the morning, alone on watch, a reserve feels less like weight and more like a friend who has not yet been needed.
Late Arrival
We tied up at a quarter past twelve, three hours and forty two minutes after the paper plan said we would, greeted by a friend ashore who had kept lunch warm and then sensibly stopped keeping it warm. Nobody was in danger at any point in those extra hours. Nothing broke, nothing tore, nobody even got wet. The only casualty was an estimated time of arrival, which is the most expendable thing on any boat.
Reflection
What I took home from that passage is a habit, and it is a counting habit, so it suits me. Do the sums early and do them honestly, especially the midnight ones, when the speed has changed and the plan has not yet admitted it. The full passage speed averaged 4.7 knots in the end, a number nobody could have used at any point during it. The useful number was always the next one: the miles remaining divided by the speed we actually had. The sea does not read your plan, and it does not need to. If you keep count, it tells you the truth in plenty of time to put the kettle on, warn the friend ashore, and sail the slower miles in good humour instead of in argument with the clock.