Shipboard discipline was much looser in the fifteenth century than it is aboard naval or even merchant vessels today. The law code of the sea was called the Code of Oleron, after an island on the coast of France. The statutes of this code protected the captain from lawsuits by merchants if the cargoes were lost in a tempest or if the ship sank. They also bade the captain consult with his crew before sailing to determine the safety of the conditions, and also made him take care of sailors who fell ill during their service. Also, some of the penalites were rather barbaric by our standards.
Entertainment seems to have been very rare.
Ships' logs document religious festivals being observed while en route during the voyages of the explorers, and it is probable that if the crew of a merchantman was at sea during a holiday, that they would act in a similar fashion, very little can be said of what the sailors did in their spare time. Instruments were carried by troopships, but one cannot speculate if other ships carried musicians other than the random man with talent. We can get an idea of what a ship of the day looked like, and how it worked on a mechanical level. We can get an idea of how its shape evolved to become more efficient in its use of wind and wood. We can also get a very good idea of how it was guided from place to place, and a good idea of admiralty law.