Douglas Harper's Etymology Dictionary
1727, of unknown origin, probably from Danish jolle (17c.) or Dutch jol (1680s), both related to yawl; or it may be from Middle English jolywat (late 15c.) "a ship's small boat," of unknown origin.
Wiktionary
n. A type of ship's boat of the 18th and 19th centuries, used mainly to ferry personnel to and from the ship.
WordNet
n. a yawl used by a ship's sailors for general work [syn: jolly]
Wikipedia
The jolly boat was a type of ship's boat in use during the 18th and 19th centuries. The origins of the name is the subject of debate, but it was by the 18th century one of a number of ship's boats, and was used mainly to ferry personnel to and from the ship, or for other small scale activities. The design continued to evolve throughout its period in service.
Usage examples of "jolly boat".
There could be no doubt that the other members of the jolly boat's crew were on the yard, and that Clough had led the way to the starboard yardarm.
She abandoned the jolly boat where it lay and crossed the sand spit to Callinde.
It fell into the sea half-way between the ship and the cliff and the jolly boat leapt forward to grab it before it swung back through the water against the foot of the cliff, and brought it back to the Juno.
The men in the jolly boat had found time and breath to curse and envy the lot of Inch's party.