HMS Deptford was a 60-gun fourth rate ship of the line

Ship of the line

A ship of the line was a type of naval warship constructed from the 17th through the mid-19th century to take part in the naval tactic known as the line of battle, in which two columns of opposing warships would manoeuvre to bring the greatest weight of broadside guns to bear...

 of the Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

, built to the dimensions of the 1719 Establishment

1719 Establishment

The 1719 Establishment was the first formal 'Establishment' laid down to govern the construction of all ships built or rebuilt down to those of 20 carriage guns, whether in the Royal Dockyards or by commercial contractors...

 at Deptford Dockyard, and launched on 22 August 1732.

In 1752, she was cut down to a 50-gun ship. In 1761, the ship sailed to Jamaica

Jamaica

Jamaica is an island nation of the Greater Antilles, in length, up to in width and 10,990 square kilometres in area. It is situated in the Caribbean Sea, about south of Cuba, and west of Hispaniola, the island harbouring the nation-states Haiti and the Dominican Republic...

 carrying a timekeeper

Timekeeper

A timekeeper is an instrument or person that measures the passage of time; in the case of the latter, often with the assistance of a clock or stopwatch...

 built by John Harrison

John Harrison

John Harrison was a self-educated English clockmaker. He invented the marine chronometer, a long-sought device in solving the problem of establishing the East-West position or longitude of a ship at sea, thus revolutionising and extending the possibility of safe long distance sea travel in the Age...

, as a part of a series of experiments used to determine longitude

Longitude

Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....

at sea. Deptford was sold out of the navy in 1767.