Officers on board sailing vessels maintained detailed logbooks of the ships’ activities. These observations, which could be made several times per day, mostly included the ship’s position and weather conditions (temperature, wind intensity, and direction). Their main purpose was to assist navigation, particularly since it was difficult to estimate the longitude accurately. As many vessels were engaged in military and commercial activities, such as for trading companies (e.g. English East India Company, Dutch East India Company), a large number of ship logs have been kept in national archives. Between 2000 and 2003, a project financed by the European Union, labeled Climatological Database for the World’s Oceans 1750-1850, digitized a large sample of log entries, including their location.
The above map plots the density of a large sample of ship logs, which is indicative of the global trade network structure of the 18th century. Due to differences in the number of log entries geocoded, such as only 7,698 entries for French-flagged ships instead of 83,036 entries for the UK flagged ships, density variations are not necessarily reflective of the size of nationally flagged fleets and their level of commercial activity. Limited shipping is observed over the Pacific Ocean, mostly due to the yet limited scale of European involvement in this part of the world at that time. The second half of the 19th century will see an intensification of maritime trade to and across the Pacific, with the First Opium War of 1838-42 being the turning point. The China trade was mostly serviced by Portuguese flagged ships, which were not covered by the sample. The following observations can be made regarding the respective trade patterns of national flagged ships for the 1750 to 1810 period:
- Spain. The Spanish trade was mainly focused on their American colonies, particularly Mexico (which was linked to the transpacific trade through an overland route), Cuba and Hispaniola. The transatlantic triangular trade system follows the pattern of wind and sea currents that incites to use the southern part of the North Atlantic for westbound travel and the northern part of the North Atlantic for eastbound travel. The second main component of the Spanish maritime trade network concerns the Argentinian trade. Less visible are the connections to Chile and Peru through the Strait of Magellan.
- Netherlands. The Dutch maritime trade network is mostly associated with the activities of the Dutch East India Company (VOC), with a long-distance network heading towards VOC’s main trade ports of Batavia (Indonesia) and Galle (Sri Lanka) and using Cape Town as an intermediary staging point (a Dutch colony between 1652 and 1806). Dutch interests were also involved in the triangular transatlantic trade with their colonies of the Caribbean and Guyana (Dutch colony between 1616 and 1814).
- United Kingdom. Its trade network is the most extensive as it reflects the emergence of the UK during that period as the world’s dominant maritime power with colonial interests in the Americas and South Asia. The Arctic trade segment is mainly related to the activities of the Hudson Bay Company established in 1670 for the fur trade around Rupert’s Land.
- France. The trade network depicted by French-flagged ships is the simplest and limited to the triangular trade structure between France, its Caribbean colonies (Haiti, Guadeloupe, and Martinique), and New France (St. Pierre and Miquelon after 1763).