Institute of Naval History and Culture
Beginning at the start of the age of the maritime discoveries of the Hispanic kingdoms (Castile and Portugal), with the establishment of transoceanic voyages, ships progressively increased in size and the complexity of their rigging until they became the massive vessels of the 18th century. But there was no revolution in their nature until the early 19th century, when steam propulsion was introduced, liberating them from the dictatorship of the wind.
This was followed by the construction of iron hulls, which lent them much greater solidity, and the spread of the propeller. In the late 19thcentury, electricity was introduced. In the 20th century, various propulsion systems appeared (diesel engines, gas turbines, nuclear reactors and others), along with radio communication, and electronics, which gave way to automation. Today, ships require smaller and smaller crews, and there are even some entirely without any crew, steered by remote control.
At the same time, throughout this entire period, ports were equipped with structures for the loading and unloading of cargo and people, and today ships regularly dock at quays or wharfs. And for loading and unloading at sea, in addition to small boats, helicopters are occasionally used. There are also aircraft carrier warships.
Given the irrelevance, when it comes to making calculations, of believing that the Earth revolves around the Sun, as Copernicus argued, rather than representing the Earth as fixed and the centre of reference, the much-lauded Copernican Revolution had little effect on navigation. However, improvements in the observation of celestial bodies due to advances in optics, improvements in the precision of nautical instruments – particularly with the introduction of the sextantin the 18th century – and the greater mastery of mathematical science, resulted in more accurate locating of celestial bodies, which made navigation more precise.
Calculating longitude on land was relatively easy, observing the timesof the eclipses and other visible astronomical events, or simply, the angle the Moon forms with other celestial bodies. But at sea – where the occasional determination of the position of a specific geographic point is not enough and astronomical observations are less precise – itcontinued to be a problem until improvements in the precision of chronometers made it possible to make more exact calculations than the method of estimating by course and speed from the previously known longitude. This did not occur until the 18th century.
Maps continued to improve in both quality and quantity. The new projections used to capture the spherical shape of the Earth on a flat surface to represent maps, like the Mercator projection, made it muchmore practicable to capture the route on a map, to determine what courses to follow and to calculate distances between points.
As previously unknown territories were discovered and colonised, the depths were sounded and the coasts delimited, capturing this information on nautical charts, making coastal navigation less hazardous. Today, ships use digital mapping and satellite positioning, which bring a precision and safety to navigation unimaginable at the time of the Magellan–Elcano expedition. With the extremely recent appearance of AIS (automated information systems), through which each ship broadcasts its position, course and speed, and the dissemination of that information via the Internet, the invisible world of ship movements on the open sea has passed into history.
The greater capacity for movement by ship beginning in the 19th century, and better knowledge of the routes to follow, reduced the duration of sailings from port to port, thus relieving the need to subsist on non-perishable foodstuffs.
Later, with the appearance of refrigeration in the 20th century, the lack of fresh food is now little more than a bad memory aboard ships that plough the seas. Today, the dietary challenges of navigation are reduced to the difficulty of cooking and eating on a floor that is moving, sometimes violently.
Since the 16th century, on-board health has improved similarly to what happened on land, and ships, in proportion to their displacement, have good hygiene and sanitary facilities. Scurvy ceased to be a problem when it was discovered that a good diet of vitamins, easily obtainable from long-lasting fruits (such as lemons), would prevent and cure it.