This article is a study of the origins, the geographic scope and nature of the maritime activities of the shipmasters engaged in the cabotage on the western coast of France in the 18th-century and elucidates how the extent of the crewmen's maritime activities was determined. First, this study makes clear by research on the geographic origins of the crewmen who obtained qualifications to become shipmaster that there were specific regions that produced more shipmasters for the cabotage. In addition to the Ordonnance de la marine instituted in 1681, there were subsequent royal edicts, i.e. navigation au long cour, grand cabotage and petit cabotage that legally established categories of maritime trade. The shipmasters of the cabotage obtained their qualifications by taking examinations based on the three categories as determined by the state. In contrast to crewmen who lived in large port cities with ocean-going vessels such as Bordeaux where there was a demand for shipping for colonial trade who desired solely to become shipmasters in the category of long-distance transport. Those who engaged traditional regional trade from relatively small ports such as Blaye and Arcachon sought to become shipmasters of the cabotage. Second, the activities of the shipmasters of the cabotage were defined by their places of origin or residence. Crewmen first went aboard ships of their relatives involved in the cabotage as apprentice seamen and received practical training and mastered seamanship. Family members were given preference in recruiting crews, and the next to be hired as crewmen were those from the same parish. Additionally, in many cases the captain was the shipmaster, and in other cases the names of members of the captain's family or local merchants could be found among the owners of the ships. It was rare for outsiders to participate as shipmasters of ships that were fitted out at Blaye or Arcachon. In this way, family capital and local ties were the basis of the operation of the cabotage. Third, the result of these profound local ties, the economic activities of the captains and their familial traditions were reflected in the geographic scope of the captains' maritime activities, and a loose segmentation in the regions of maritime activity occurred according to the region of origin. The employment of crewmen, the paying of wages, the handling of cargo and determination of the route were carried out according to the captains' orders. Places with a demand for goods produced in localities associated with a ship's captain or places that produced goods that were in demand became important destinations for these captains. As new markets for local goods were created by colonial trade and military activity, the captains' area of maritime activity changed correspondingly. And yet, this change did not greatly alter the scope of the traditional activities of the captains, and the change was ultimately confined within the scope of the coastal trade. The captains altered the extant of their maritime activities in response to the trends in the market while implementing geographic segmentation but within the categories of grand cabotage and petit cabotage