From A Land So Strange: The Epic Journey of Cabeza de Vaca, by Andrés Reséndez (Basic Books, 2007), Kindle pp. 59-61:
The Florida expedition left the Spanish coast on June 17, 1527. The novelty of sea travel, the anticipation of life in another continent, and a natural curiosity for the vessels and their occupants would have made the eight- to ten-day journey to the Canary Islands bearable. Fleets headed for the New World normally stopped briefly at Gran Canaria or La Palma to restock with water, wood, live animals, and some other provisions.
An entire month of open-ocean sailing across the Atlantic began when the ships departed the Canaries. By now the passengers would have had a very good idea of the level of endurance needed for the journey. The most aggravating factor was overcrowding. By our modern standards, sixteenth-century ships were appallingly small, measuring around 20 yards in length by 5 yards across by 2.7 yards of depth. All told, there were between 1,615 and 2,153 square feet of habitable space—roughly the surface area of a good-sized apartment. Within the confines of this space, some 100 to 120 human beings commingled day and night for weeks, using the most rudimentary latrines, and with no privacy at all except in the rarest of cases. On average, each person on board had a suffocating 1.8 square yards to himself. The luggage made the limited space more unbearable still. Travelers brought a variety of chests, boxes, and personal effects that inevitably ended up scattered all over the deck, cluttering every nook and cranny. Fights sometimes erupted when someone moved a chest just a few inches, unavoidably encroaching on a neighbor’s area. Voyagers were also forced to share their precious space with numerous animals, some deliberately transported and others uninvited. Chicken coops abounded, and pigs, goats, sheep, cows, and horses were also included in these voyages. From a distance, the decks of some of these vessels must have looked like veritable floating farms. The uninvited guests were surely the worst, however—rats, fleas, and lice roamed freely through the ships and mingled with everyone on board, recognizing no distinctions of social rank.
Overcrowding affected every single facet of life. Food and drink, for instance, were made available in a centralized, regimented fashion to all but the privileged few. Ordinary travelers could expect three square meals consisting mostly of water, wine, and hardtack (unleavened bread), with occasional meat and soup dishes. Unfortunately, the large number of mouths to feed put a premium on expediency rather than quality or flavor. Passengers found many reasons to complain. They noted the murkiness and smelliness of water; wine, even the cheap and watered-down kind, was always far more popular. The hardtack was dependably dry, blackened, rancid, and often bitten by rats and covered with cobwebs. Neither did the passengers have much praise for the salty, leathery, half-cooked meats that only increased the pangs of thirst. Polite eating manners were out of the question. Two, four, or more individuals shared big platters that were placed on the floor since there were no tables. Everyone took food liberally with his or her hands and passed around knives as necessary (conditions were not necessarily much better on land, as spoons and forks were just becoming widely used in Europe, amid some skepticism. Objecting to the use of forks, one German preacher remarked that God “would not have given us fingers had he wanted us to use this instrument.”).