Final answer:
Sailors were unhealthy primarily due to poor hygiene, limited access to fresh food and water, and the risk of infectious diseases spreading on long voyages.
Step-by-step explanation:
In the context of sailors, poor hygiene, close quarters, and lack of proper nutrition were the main reasons why most sailors were unhealthy. During long voyages, sailors faced unsanitary conditions, limited access to fresh food and water, and the risk of infectious diseases spreading. These factors contributed to a high mortality rate among sailors and poor overall health. For example, on slave ships, sailors faced the constant fear of illnesses like trachoma, which could lead to blindness and reduced their profits.