Our present knowledge of the marine climate, as represented by data sets such as COADS (Woodruff et al., 1987), is based on meteorological observations from the Voluntary Observing Ships (VOS). Because the VOS are merchant ships, rather than specially designed meteorological platforms, errors and biases exist in the data. However there is little information readily available to the climatologist either on the nature of the VOS fleet or on the observing practises which are used. This report, describing the forty-six ships that participated in the Voluntary Observing Ships' Special Observing Project - North Atlantic (VSOP-NA), therefore serves two purposes:(i) it provides a reference document to aid analysis of the VSOP-NA data set,(ii) it gives a detailed description of a subset of the VOS, which will be of value in the interpretation of marine climate data sets.This report is in two parts, Part 1 is an overall summary of the ship characteristics, Part 2 is a ship by ship description. The next section will briefly describe the VSOP-NA project, followed by a summary of the characteristics of the VSOP-NA ships (Section 3). Since these ships were specially selected (Section 2.2), the degree to which they are representative of the whole VOS fleet will be carefully considered. The meteorological instrumentation used by the VOS varies depending on which meteorological agency recruited the ships. That used on the chosen VSOP-NA ships is typical of VOS recruited by the countries bordering the North Atlantic, and will be described in Section 4. Section 5 is a summary of Part 1 of the report.Part 2 presents the VSOP-NA ship catalogue. This includes, for each ship, diagrams of the layout (indicating in particular the exposure of the sensors), a summary of the geographical positions at which observations were obtained, and details of the instrumentation used.<br/
