Ben Lowings looks at the history of this most accurate of timepieces, and ponders if a marine chronometer is still needed onboard today

Does a marine chronometer still have a place onboard?

It is a truth universally acknowledged is that if you slap the adjective ‘marine’ in front of any noun, its sale price shall increase by an exponential factor.

You can get a kitchen clock from Argos or Dunelm for a tenner.

A marine chronometer, say, Wempe’s 2023 Tim Heywood design: £46,400.

A watch in a silver case

To prevent disturbance to the balance wheel, chronometer watches were kept with the 12 o’clock position pointing upwards. Credit: NTERFOTO/Alamy

One boat owner might scoff at another for buying ‘a fancy clock in a box’, but Wempe’s chronometer is ‘gimballed within a cube of fine wood’.

A sailor might want to buy several ocean-going yachts instead, but Wempe’s £74,508 masterpiece – the dial concealed within the gold-lined doors of mock coco de mer nut – is ‘a thing of beauty, a joy for ever’.

I laugh, if only to mask the fact I secretly covet it as the conversation piece for my mega-yacht’s saloon.

Mechanics of a marine chronometer

Mechanical chronometers, such as those developed from John Harrison’s H1 in response to the conundrum of longitude, invite the touch.

They need to. They are wound by hand.

Through a process called ‘escapement’ the energy ‘escapes’ in regular bursts to measure the passing seconds.

The best layman’s explanation of the mechanics lies in Dr Bill Morris’s book, The Mariner’s Chronometer (CreateSpace, 2012).

As the self-taught amateur explains, the “balance wheel vibrates under the influence of a balance spring… The vibrations are used to regularly unlock a clockwork motor, so it runs down in equal steps, driving the hands as it does so. The clockwork also gives a tiny push to the balance wheel to keep it vibrating.”

Marine chronometers, he adds, “have an indicator dial showing the state of wind. Most will run for 56 hours and relatively few were made to run for eight days.”

Ship’s officers down the centuries have used the gloriously named tipsy key to wind them. ‘Tipsy’ because of a clutch inside that disengages if you try to turn the key and wind the spring the wrong way.

“Chronometers were always wound daily at the same time and the fact formally reported to the ship’s master,” Morris says.

Wempe’s Marine Chronometer Cube has been styled by British superyacht designer Tim Heywood. Credit: Wempe

Wempe’s Marine Chronometer Cube has been styled by British superyacht designer Tim Heywood. Credit: Wempe

The principle behind this was that the same stretch of spring would always be used.

The case was protection from salty air. Gimbals held dials face up, steadied against lumpy seas.

The machines themselves have been refined by improving components’ quality.

For example, in Wempe’s workshop in Saxony, galvanic coating has been added to the 2023 model’s bimetallic balance wheel.

“This is a precision instrument,” their engineer, Carsten Petersen, informed me. “It deviates a maximum of 0.3 seconds per day. This means it should be wound daily at best, but at the latest after 56 hours.”

I look at my £30 Casio watch. Wound daily? What a faff. Since the 1970s electronic clocks have been the norm.

A quartz crystal, subjected to a small electrical current from a battery, oscillates with magical regularity, providing accurate ‘movement’.

Continues below…

Japan’s Tamaya Seiko issued reliable electronic chronometers.

The QM-11 is a 1970s piece of furniture that frankly looks more like a bomb. Should James Bond have had to defuse it, a tipsy key would be of no use.

Today’s evolution might well be the Apple Watch Ultra (£849) or for a mariner with an eye for tradition, the Schatz Midi or Royal Series from Delite.

 By the 1970s, electric chronometers, like the Tamaya Seiko QM-11, were available

By the 1970s, electric chronometers, like the Tamaya Seiko QM-11, were available

They are made just west of Copenhagen by Peter Jessen. He founded Delite in 1996.

For Jessen, a quartz clock updated with a GPS clock signal, “rules out” any previously built chronometer.

Replacement batteries

Most electronic ones did not have a state of battery indicator. “They would run sometimes for more than a year on the same battery,” explains Bill Morris.

“Many [ship’s] masters would have insisted on a change at the end of each voyage or have some standing order about time of replacement.”

Jessen’s cases are his nod to tradition, being of polished chromium plated brass.

Some in the Schatz range, similar to the chronometers aboard Clipper Race Training 68s, have portions of the dial shaded green or red, to show the division of watches.

Good if all crew are aware… Bad, if the only crew who refer to it have red headtorches, which blot out the port times and leave the starboard watch in an intermittent black line.

Another Jessen option to regulate the crew’s watch system – again, not for some – is a ship’s bell striking mechanism.

Long-term investment

Aside from mere functionality is investment value. Thomas Mercer founded his chronometer firm in 1858.

It equipped Shackleton’s Endurance.

Its managing director, Alessandro Quintavalle, told me their timepieces are “technically very close to those manufactured in the age of sail. While now incorporating a design – and furniture – dimension, it is paramount for us that the mechanisms be authentic compared to their ‘ancestors’. Offering today a 200-year-old craft is what makes them highly coveted by collectors.”

A photo of men launching a small boat into a rough sea

Sir Ernest Shackelton used his Mercer No.5229 to safety navigate James Caird the 800 miles to South Georgia to seek rescue for his men trapped on Elephant Island. Credit PA Images/Alamy Stock Photo

Indeed, the Mercer chronometers were held in such high regard by Ernest Shackleton and his skipper, Frank Worsley, that despite the rigours of a small boat voyage they considered them too reliable to leave their last remaining one behind on Elephant Island.

The trip up from Elephant to South Georgia in the James Caird is the stuff of navigational legend. Shackleton’s Mercer – No.5229 – is now in the National Maritime Museum at Greenwich.

Shackelton's Mercer No.5229 marine chronometer. Credit: National Maritime Museum, London

Shackelton’s Mercer No.5229. Credit: National Maritime Museum, London

Recent scholars have suggested Shackleton used this very instrument as a backup perhaps for interval timing.

Worsley’s log showed he relied on a separate smaller pocket chronometer from S. Smith and Son.

He kept this under his sweater, to keep it at a constant temperature, shielded from the remorseless cold of the Southern Ocean.

It was hung around his neck, as chronometer watches were kept with 12 o’clock up, usually in a waistcoat pocket, so as not to disturb the balance wheel.

“I imagine waistcoat pockets were in short supply on the way to South Georgia,” Bill Morris remarks.

Double check

Navigation experts have established that Worsley deliberately added an extra minute of error to the time from his chronometer, so it would suggest his longitude was more to the east than he really was.

He really didn’t want to overshoot South Georgia, with thousands of miles of empty ocean to the east of it.

Shackleton’s Mercer could have been useful to double check Worsley’s watch, as a control instrument.

It was a similar idea in the old navy when several officers would observe with their sextant at once.

Perhaps that’s a good place to wind up this article about chronometers.

Yes, they are lovely, and reliable, but maybe the best lesson the small-craft navigators of old can offer is not to trust them – and, if you can, have two.

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