The Climatological database for the world's oceans (CLIWOC) was a research project to convert ships' logbooks into a computerised database. It was funded by the European Union, and the bulk of the work was done between 2001 and 2003. The database draws on British, Dutch, French and Spanish ships' logbook records for the immediate pre-instrumental period, 1750 to 1850. Logbooks in review Logbooks from the eighteenth and early nineteenth century had previously been used in case studies of individual events of historic or climatic interest. CLIWOC established early ships' logbooks as another source for those seeking to understand climate change, to be used alongside proxy and instrument data. The observations were made at local noon every single day, and cover most of the world's oceans - only the Pacific Ocean lacks detailed coverage. This volume of data was not available by any other means. Interpreting the data In researching the data, CLIWOC staff found that the data need to be treated with caution, and subjected to careful scrutiny. The range of information - wind force terms and directions, and general weather descriptions - is consistent between the different national sources. The data was primarily based on observations made by experienced officers. Though each book used consistent terms to refer to wind speeds, these values were not always consistent between logbooks. The researchers chose to standardise the terms into their Beaufort scale equivalents. The vocabulary used also differed between the national sources - British mariners used a relatively narrow range of terms, while sailors from the Netherlands, Spain, and France used a wider set of descriptions. Researchers found that the majority of wind force entries were accounted for by twelve or so terms, allowing the group to prepare a dictionary defining most wind force terms in use. This multi-lingual dictionary has also been published. Data verification In order to establish the reliability of logbook records, the researchers looked at readings taken where ships were in convoy or travelling in close company. These voyages often lasted several weeks, giving large samples. The research showed that there was a consistently high degree of correlation in recorded wind forces and recorded wind directions. On a number of occasions, the records showed small but persistent differences between absolute wind force records prepared on ships of different sizes. This was adjudged not to materially influence the scientific outcome of the project, but remains a matter for