Timing 300 ferry crossings with a stopwatch

Ardnish Ferries runs two small car ferries in the West Highlands. When they called us, one sailing in five was leaving late, and the complaints had started reaching the council.

The crews already knew why. Loading took longer than the timetable allowed, mostly on summer mornings and Friday evenings, when the queue was full of camper vans and trailers. The timetable hadn’t changed since 2009. The traffic had.

Measure what the crews describe

We spent three weeks on the slipways with stopwatches and clipboards, starting with the first sailing at six in the morning. For 300 crossings we timed every stage, from the first car rolling onto the slip to the ramp going up on the far side, and noted what was in the queue. We also rode the boats at the busiest times, because the delay on the far slip only made sense once we had seen how little room there was to turn.

The numbers matched what the crews had said and showed exactly where the minutes went. A camper van took three times as long to load as a car. On a summer Friday the queue held four times as many of them as in March.

Ask the people who do the work first. Then measure, so everyone else believes them.

Four minutes in the right places

We built the new timetable around those numbers. It adds four minutes to the sailings where loading runs long and takes them back in the quiet hours, so the day still ends on time. One afternoon sailing moved by a quarter of an hour to fit the school day, which took the busiest school run out of the evening queue.

It needed no new boats and no extra crew. The hardest part was getting new timetables onto every shop counter and noticeboard on the route.

On-time sailings rose from 78% to 94% in the first summer. The crews say the slip is calmer, too.