Final answer:
In the 17th and 18th century, the "problem of longitude" was a significant concern for maritime powers. John Harrison, a British clockmaker, developed accurate chronometers to measure longitude at sea, solving the problem. These chronometers were then used to split watches into port and starboard to ensure precise timekeeping on ships.
Step-by-step explanation:
In the 17th and 18th century, when the navies of Britain, Spain, France and Holland all tried to dominate the seas, the "problem of longitude" assumed great strategic importance. To accurately measure longitude, sailors needed a reliable way to track time. John Harrison, a British clockmaker, spent decades creating accurate chronometers that could keep time at sea. This solved the problem of longitude and earned him a prize from Britain. His chronometers were eventually used to split watches into port (morning) and starboard (afternoon) to maintain precise timekeeping on ships.