A launch is an open motorboat. The forward part of the launch may be covered. Prior to the era of engines on small craft, a launch was the largest boat carried on a sailing vessel, powered by sail or by oars. In competitive rowing, a launch is a motorized boat used by the coach during training.
Launch (boat) Wikipedia
Originally a launch was the largest boat carried by a warship in the age of sail. The word comes from the Spanish lancha ("barge") and Portuguese, from Malay lancharan ("boat"), from lanchar ("velocity without effort").
In the Age of Sail, a ship carried a variety of ship's boats of different sizes and used for different purposes. In addition to the launch, examples include the jolly boat, captain's gig, pinnace, and cutter. Distinctions among the smaller vessels were clear, both in design and purpose. In the age of motorized ships, these distinctions of size and purpose have largely disappeared, but the terms continue in use.
In the 18th century, a launch was used to set the large anchors on a ship. The launch of that era had a square transom and was about 24 feet long. In 1788 Captain Bligh was set adrift in Bounty’s launch.
On the River Thames the term "launch" is used to mean any motorised pleasure boat. The usage arises from the legislation governing the management of the Thames and laying down the categories of boats and the tolls for which they were liable.
Motor launch was the designation for large (typically 60-to-115-foot or 18-to-35-metre long) vessels used in the Second World War by the Royal Navy and some other navies. They were used for inshore work in defending the coast from submarines and carried relatively light armament: a few depth charges, a gun and a few machine guns.
In competitive rowing the term "launch" is used to refer to any motorized boat used by the coach to follow practicing boats during workouts.