In the 18th century, timekeeping on land was very much a local affair. There were no time zones, nor any concept that a whole area should be obliged to share a single time. The hour in a particular place was generated from a prominent shared clock, such as that on the village church, or mounted on the front of the town hall. Its chimes rang out to inform one and all the time, and those wealthy enough to have their own clock or watch would adjust it accordingly. It provided a convenient way of arranging the start of a local event, or meetings between people, but it mattered little if the time in one town was different from that in the next. It was only the advent of the railways in the 19th century, with their requirement to publish timetables, that forced whole nations and regions to settle on a single time.
At sea, timekeeping was a more precise affair. Ships carefully maintained their own onboard time. It was fixed each day when the sun reached its zenith and the vessel’s position was calculated. That moment was declared as noon and was the start of the sailors’ working day. Another ship a single degree of latitude away would calculate its noon as being four minutes different. If a ship was sailing on an east/west course, its “day” (defined as the time between two noon sightings) was never exactly twenty-four hours long. Just as modern plane passengers who travel between time zones can experience variations in day length, so in a smaller way can ships. Before the start of the Second World War, Eric Newby voyaged from Australia to Cape Horn across the Southern Ocean on a grain barque. He notes in his account of the voyage that on occasions when the ship was moving quickly, a day could last as little as twenty three and a half hours.
The reason for precise timekeeping at sea when compared with on land was because, to a mariner, time is a vital part of navigation. The angle between the horizon and the sun will gives him his latitude, but only if taken exactly at local noon. With the arrival of the first marine chronometers towards the end of the 18th century, time became even more important because it also gave him his longitude. The chronometer was set to show the time at a fixed line of longitude on the earth’s surface - normally Greenwich. When this was compared with local noon, the difference told a ship’s master how far around the world he had travelled.
Once noon had been fixed, the routine of the ship during the following day was regulated by its bell. Each ship was equipped with a large brass one which served both to count time, and as a handy device to warn of the vessel’s presence in thick fog. Crews were divided into two watches, who took it in turns to man the ship. The bell was sounded every half hour, one stroke for the first thirty minutes, two for the next and so on, until eight bells was reached after four hours. The watch then changed over, and the series of bell strokes started again. The exception to this was the dog watch which took place between 4.00 pm and 8.00 pm and was split into two two-hour watches. This split watch meant that the less popular periods of duty (such as that between midnight and four in the morning) alternated between watches each day.
Ships maintaining their own time remained vital for navigation throughout the 19th century, but in the 20th century its importance began to lessen. The introduction first of radio navigation, which used beacons on land to pinpoint a ship’s location right through to the development of GPS in our own times has meant that captains can use information from outside their vessel to navigate by. The international time zones that are used on land are now shared by mariners too, while ship’s bells are reduced to largely decorative reminders of a time when they closely regulated life afloat.