- Has Sight of 3.
Naval melee units, unless under Harald Hardrada, are the class of units with the most limited scope of use. On land, units with melee attacks are generally "blocker" units: unless they are unique units who are made for offense, they are most often used to claim strategic tiles or fortify to form a frontline shielding ranged and siege units, and only attack to capture cities. In the open sea, the role of such units significantly diminishes. Since every water tile is basically a flat land tile and naval units are a lot more mobile with their high Movement, it is very easy to circumvent naval zone of control to hit ranged naval units at the back. Furthermore, since cities in Civilization VI can always settle inland yet still enjoy the benefits of the coast, it is more reliable to bring a land melee unit together with your naval ranged units on a naval conquest. But that's not all, the way the ability to enter Ocean tiles is granted in Civilization VI makes the Caravel even less useful. Back in Civilization V, obsolete ships cannot enter Ocean tiles even if appropriate technologies are researched, but in Civilization VI, all ships can enter deep oceans after Cartography, so unless you are very generous with Gold, your Galley can still shoulder the responsibility of exploration in the Renaissance Era. For those reasons, Caravels are often relegated to a very defensive and reactionary role if you are facing a naval invasion, and only situationally can be brought along to deal the last hit to coastal cities in a naval conquest if the map is either Archipelago or Island Plates.
As Iñigo Arieta, the Spanish commander who escorted Columbus to sea in 1492 AD, put it, caravels were “corredoras extremadas, buenas para descubrir tierras.” The Nina and the Pinta were caravels, and Columbus praised the Nina for its maneuverability, speed and safety. Developed in the 15th Century and used extensively in the 16th, the caravel was a speedy sailing ship with lateen-rigged main- and mizzen-mast, sloping bow and high stern castle. It appears that the classic (there was a lot of variation) caravel design was a melding of an earlier Iberian fishing vessel and the Arab qarib plying the Mediterranean. Small, light and shallow-drafted compared to other sailing ships, it was perfect for exploring all those coasts and rivers the Europeans were finding during the Age of Exploration. Likely the first vision people had of Europeans was a caravel looming off of the coast. After the explorers came the conquistadors, priests, adventurers, traders and eventually settlers...and so the unpretentious little caravel spread conquest round the globe.