The performance capabilities of ships were controlled by four factors: their ability to tack into the wind, their inability to survive in heavy seas, the speed that their crews could sustain under oars over time, and their stowage capacity for provisions, especially for fresh water. A ship covered the minimum distance of around 1030 miles from Constantinople to Alexandria, at the onset of winter, in 8-8.5 days, an average speed of around 4.4 knots if sailing around the clock. At the beginning of the seventh century no ship could reach Alexandria from Constantinople, not even the fastest imperial dromon. Aboard the seventh-century Yassi Ada wreck there was found a single, large, globular pithos which had no handles, unlike all the other amphorae, and was obviously set in place somewhere aboard ship. The ship sailed for Gaza after spending only enough time in port to take water on board.