Resumen

SNIJDER RUAN, Laura I. Reconstruction of the course of the ship San Ignacio of the Guipuzcoa Company (1738). Tiempo y Espacio [online]. 2015, vol.25, n.64, pp.72-93. ISSN 1315-9496.

In this research, we reconstructed in Google Earth the course followed by the ship San Ignacio of the Guipúzcoa Company in its third voyage, from the port of Pasajes to the port of La Guaira, which lasted from July 20th to  September 3rd 1738. To achieve this, we have relied on the ship log of the pilot Joseph Ugalde. The goal of the research is to determine the accuracy of the estimates of the coordinates, latitude and longitude, which are reflected in the log. We had to make a correction of longitude, as it was based on the meridian of Tenerife and not on the Greenwich Meridian, as it is done today. Because we did not get the exact references of both meridians difference in degrees, minutes, and seconds, we had to estimate it based on an observation made by the pilot of the west cape of Madeira on August 3 rd , 1738. Once we had corrected the coordinates of the log, we plotted each point in Google Earth and joined them with a straight line. The estimated path of the ship is logical, even when it is obvious that is has a margin of error. We conclude that measurements of the pilot are considerably accurate. However, the details of astronomical observation methods used by the sailors of the Guipuzcoa Company to determine the latitude and longitude of the point where they were is for further study. This way, we could explain the accuracy of the relevant observations.

Palabras clave : ship log; coordinates; latitude.

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