By Judith Burns
Science and environment reporter, BBC News
Whytootackay Island by Lieutenant G Tobin aboard HMS Providence in 1792
Scientists hope weather data from 18th Century ships' logbooks will throw new light on how the climate has changed in the past 200 years.
A new UK project is digitising nearly 300 Royal Navy captains' logs from voyages dating back to the 1760s.
They include the voyages of Charles Darwin on HMS Beagle, Captain Cook's log from HMS Discovery and Captain Bligh's journal from The Bounty.
The logbooks will be available on the National Archives website next year.
But scientists are already transcribing the data as part of a project led by the University of Sunderland.
The logbooks contain detailed records of weather in the oceans, which were updated daily or even hourly by senior officers.
There are measurements of wind speed and direction as well as temperature and pressure recordings. As time went on the measurements became more instrumented and accurate.
The logs are proving to be a vital tool for modern day climate researchers, who are using them to build up a picture of weather patterns in the world at the beginning of the industrial era.
The researchers are cross referencing the data with historical records for crop failures, droughts and storms and will compare it with data for the modern era in order to predict similar events in the future.
David Parker of the Met Office Hadley Centre told BBC News: "The idea is to extend the data back further so you can develop statistical models of the relationship between weather patterns and harvests and so on, (and) apply those relationships to the future expected weather under climate change."
A detail from Captain Bligh's log from The Bounty in 1788
Climatologist Dr Dennis Wheeler from the University of Sunderland said: "The observations from the logbooks on wind force and weather are astonishingly good and often better than modern logbooks.
"Of course the sailors had to be conscientious. The thought that you could hit a reef was a great incentive to get your observations absolutely right!
"What happens in the oceans controls what happens in the atmosphere. So we absolutely need to comprehend the oceans to understand future weather patterns."
The logs not only contain records of the weather but footnotes and personal observations of life on board, and the places and people the crews encountered on their voyages.
Oliver Morley of The National Archives said: "The logbooks have long been of interest to historians and naval enthusiasts, and the fact that they are now being used for scientific research is a great example of how archival information created for one purpose can be re-used for something entirely different."
The Royal Navy ships' logbooks will also feed into a larger international project known as Acre (Atmospheric Circulation Reconstructions over the Earth), which aims to build historical climate records from observations only.