Navigation – and Their Journey

Navigation was more basic in the 16th century than it would be today.
All the ship’s captains had been given copies of charts and maps to help with navigation. The Spanish had some knowledge of the route around the north of Scotland but their charts had no details for the coast of Ireland.

Navigational tools were found on La Trinidad Valencera and included a mariner’s compass and a pair of bronze navigational dividers. If you visit the exhibition you will see some of these navigational instruments on display.

The Navigator

The navigator was one of the ship’s officers and was educated in astronomy, mathematics, latitude reading and the study of the oceans. From 1508 onwards a school in Seville trained the royal navigators. After a voyage the navigator went back to the school to give full details of the journey to be included in future maps.
The navigator had only basic equipment, such as a compass, quadrants, an astrolabe and sounding leads.

An astrolabe was a circular bronze instrument with degrees marked around the circle. An arm was pivoted in the centre of two crossbars. The astrolabe was hung from a ring at the top and the arm was used to measure the angle of the sun above the horizon at noon.

A sounding lead was a heavy cone shaped piece of lead with a hole at the top through which a long cord was threaded. The base of the lead piece was covered in tallow (melted down animal fat) and the sounding lead was lowered over the side of the ship to gauge the depth of water and to find out if the seabed was sandy or rocky. If it was sandy the silt would stick to the tallow and the seabed would be compared with that noted on the sea chart.

The depth of water was worked by the length of line, which was measured by the sailor’s arm span, usually 6 feet or 1.8 metres –
this measurement is still used today.

How do these instruments compare with the way ships navigate today?

16th century maps were not as accurate as the maps we have today..