How did a small, light ship open the African coast to Portugal?

Portugal could creep down the African coast because of a small, light ship called the caravel. A typical one in the 1400s was only 12 to 18 metres long and carried 50 to 60 tons. That is tiny, but it was very fast and easy to steer, and it could sail windward, meaning against the wind, which made it largely independent of the prevailing winds. A captain with a ship like that could probe an unknown coast without depending on the direction of the wind.

The man behind many of these voyages was Prince Henry of Portugal. His aims were practical: to find where West Africa's gold came from, to look for a legendary Christian king called Prester John, and to stop pirate attacks on Portugal's own coast. Most of his voyages were one or two ships creeping along the shore and tying up at night. You may know him as Henry the Navigator, but nobody called him that while he lived, or for three centuries afterwards. Two German historians coined the nickname in the 1800s. The famous 'school of navigators' at Sagres is also called a misconception by modern historians.

The real obstacle was fear. In 1424 Cape Bojador was the furthest south that Europeans knew, and sailors had long believed sea monsters and the edge of the world lay beyond it. Henry sent 15 expeditions over ten years to pass it, and every one came back unsuccessful. Finally, in 1434, Gil Eanes passed the cape, a breakthrough that opened the way to the rest of the coast.

What the ships found there was a trade that Portugal had been missing. Once the explorers were south of the desert, enslaved Africans and gold began arriving in Portugal. The same small ships that opened the coast opened a trade in people.