The term, which comes from English to jam the wind, which means “to press the wind” - ships that press against the wind or that are pressed (down) by the wind.

The term has nothing to do with moaning in the sense of the german word  jammern which means moaning, complaining, howling. Although one often reads of the wind howling in the yards.

Windjammer in the Port of Hamburg around 1900 (x) 

Windjammer is a type of tall ship that emerged after the clipper era in the second half of the 19th century and succeeded the fast sailers. They were tall ships made of wood, iron and steel and designed more for carrying capacity, handling and economy, which had to bring in profits for their shipowners. The later, cargo sailing training ships also belong to this category. Over the decades, the ships were also optimised in terms of speed and handling. Today, it is synonymous with “tall ships” and, as the last generation of windjammers, includes modern sail training ships and cruise ships such as the Sea Cloud.

Guardian of the Republic- USS Enterprise (1799), by Patrick O’Brien (1960-)

" The Wooden Walls of England" - Patrick Lyons O’Brien (b.1960) is an American artist and writer, known for his children's books and for his maritime paintings.

A pair of bone miniatures, depicting the Royal Navy vessels HMS Victory and HMS Foudroyant, used by Vice-Admiral Horatio Nelson, 19th century

Portholes are essentially just round windows, so they may not seem like a milestone in the history of sailing.

River Thames through the Porthole of HMS Wellington

But the technology required to cut a large hole in the side of a boat and then seal it to prevent any ingress of water is so sophisticated that no one has tried it for several thousand years. In fact, the fear of a leak was so deeply rooted that most seafarers vehemently resisted any attempt to cut holes in their ships - that is, until they had to win a war. It was developments in cannon design that led to the invention of the first portholes, or rather the first gun ports.

From the beginning of the 14th century, ships were equipped with artillery, but this usually consisted of small calibre weapons mounted on the fore and aft locks of the ship, which could only be used to a limited extent, as the primary combat tactic was still to allow military personnel to board an enemy ship and engage in close combat. As the big cannons began to dominate the land battles, it became clear that they will be very soon also at sea. But to carry the weight of such large weapons without making the ship top-heavy, the cannons had to be placed low down, and this meant cutting holes in the sides of the ship to create a space through which the cannons could fire.

Gunports of the Vasa, 1628

There are many different theories about who invented the cannon opening. The French claim that it was a shipbuilder from Brest, Francois Descharges, who installed it in the Grace a Dieu of Henry VIII in 1515. The Portuguese say that King John II came up with the idea when he fitted his caravels with heavy cannons in 1490. Other evidence suggests that they may have been present during the siege of Rhodes in 1480. It is most likely that, like other contemporary inventions, they were developed simultaneously in several countries. In any case, gun ports were in general use in the 1520s.

Left: A porthole from a 18th century shipwreck of a merchant vessel, found in the Bay of Bengal. Right: A late 18th or early 19th century porthole

Not that the gun ports were without their problems. The Mary Rose and the Vasa were just two of the more famous ships that were sunk when a sudden wind blew them over and allowed water to flow in through their open ports. Once the concept of piercing a hull for guns had gained acceptance, it was only a small step to cut holes for ventilation and light. And so the porthole was invented in 1569. Although most warships used their gunports for this task, a combination of both comes slowly and later. It is thought that the term comes from the French word porte, meaning door, which was inserted into a porthole. Unlike the original embrasures, most portholes are round, which gives a stronger structure that is less susceptible to rot. 

Portholes are so ubiquitous today that it is difficult to imagine a picture of a ship without a small line of circles on the hull.

Dundee Antarctic Whaling Expedition (1892–1893), by William Gordon Burn-Murdoch, 1893.

Ivan Alekseevich Vladimirov (1869 — 1947, USSR) - The sinking of the ships of the Black Sea Fleet on the Sevastopol raid on September 11, 1854.