Ariadne has spent the last few days resting, restoring, and refueling in the island of Madeira. She and her crew have set off again today at the start of the long leg across the Atlantic to Tortola. Since leaving France she has put 1000 nautical miles under her keel, and will have covered another 2700 before we see her in a month or so when she gets to her new home port.
Leaving Madeira marks another first; she has crossed her first time zone, and will cross several more before reaching the Caribbean. Knowledge of the time is a vital factor in ocean travel and navigation. Accurately knowing the time of noon at an expected place in the world gives a navigator the ability to update their longitudinal position based on the actual elevation of the sun above the horizon, compared with where they thought it would be at noon on a particular day. The noon sun-sight, together with morning and evening star sights, were the basis of accurate navigation and exploration before the development of radio direction finding equipment and then satellite navigation systems. I could spend some time on this topic alone, but others have and much more eloquently. So, if you are interested, read Longitude by Dava Sobel or visit the Royal Observatory at the Greenwich Maritime Museum in London. It’s well worth it.
That said - mistakes can, and sadly do, get made! I often chuckle at the, possibly apocryphal, story of a tiny former colonial outpost somewhere in the Pacific Ocean awaiting the arrival of a warship some 30 years ago or so. The ship was due to make a small ceremonial visit whilst on passage across the Pacific. The island governor and all the local dignitaries were assembled on the harbor wall at the appointed hour on the appointed day. Flags were flying, bands were playing, welcome marquees had been erected. The time that the visiting warship should have appeared over the horizon came… and went… but no vessel was to be seen.
Consternation turned to concern until the message went around that the unfortunate ship’s navigator had omitted to factor the time change, and more importantly day change, presented by the passing of the international date line into his calculations correctly. Consequently some time earlier while on passage he had adjusted the ships speed in order to arrive at what he thought was the right time, but it was in fact a full 24 hours late! The arrival ceremony the next day was a great deal less impressive…
The fate of the navigator and his captain, who of course is ultimately responsible for his team, was not well documented - but I am sure it was not the most career enhancing move for either of them!
No date lines to pass in the Atlantic thankfully, just 5 timezones before reaching the waters of the BVI. Can’t come soon enough.