A new method for examining maritime mobility of direct crossings with contrary prevailing winds in the Mediterranean during antiquity

The use of detailed meteorological data with sailing software, in conjunction with sailing the Ma'agan Mikhael II replica ship, has engendered the development of a method for examining maritime mobility of single-masted square sail Mediterranean merchantmen in the Graeco-Roman period, with the initial objective of mapping direct, open sea, return sailing routes from the Levant that a priori lie contrary to the prevailing wind. Many quantitative works have used averaged winds as input, and evaluated sailing passages based on climatological averages, losing information on the intra- and inter-diurnal variability of the winds. Thus their sole measure of mobility has been a representation of sailing speed on direct crossings. Moreover, these studies have not considered the difference between physical and practical mobility, the latter driven by human factors. For instance, the choice of whether to sail, or wait for better conditions. The proposed method uses climatological resources at high spatial and temporal resolutions, with the premise that using high-resolution data reveals the recurring wind variabilities and patterns that are key to mobility, especially on routes lying contrary to the prevailing winds. The method generated a large set of over 5400 simulated sailing outcomes for each route segment, permitting well-established statistical analysis. Inclusion of criteria-based human factors of the mariners of the period provides a measure of mobility, representing not only sailing speed, but also waiting time, and the probability of conducting a feasible passage at a given time of the year. This new method provides deeper insight into maritime mobility and the understanding of seafaring in the Mediterranean, and is applicable to numerous scenarios, providing a practical and improved measure of maritime mobility.