The 15th century vessel referred to in the crossword solution is the NINA, a caravel-type sailing ship used by Christopher Columbus and other explorers of the era. The NINA was a small, three-masted vessel with triangular sails, which allowed it to sail closer to the wind than other ships of the time. It was also highly maneuverable and could be sailed with a smaller crew than other ships. The NINA was an important part of the Age of Exploration, allowing explorers to travel farther and faster than ever before.