After having been twice driven back by heavy southwestern gales, Her Majesty's ship Beagle, a ten-gun brig, under the command of Captain Fitz Roy, R. N., sailed from Devonport on the 27th of December, 1831.As dramatic opening sentences go, it's one of the best: Charles Darwin's account of the Beagle leaving England on her second and most famous voyage of adventure and discovery.
But Darwin isn't quite accurate when he describes Beagle as a ten-gun brig. Although that was indeed the generic name for such ships, and Beagle had been constructed as such, she was adapted for surveying work before her first voyage, and was, by the time Darwin set sail on her, strictly speaking, a bark. Keith S. Thompson explains the difference nice and succinctly in his book HMS Beagle: the ship that changed the course of history [ISBN: 0-75381-733-0]:
a brig has two masts and a bark three. On a brig both masts are square-rigged, and the mainmast also has a large fore-and-aft sail. On a bark the fore and mainmasts are square-rigged only; neither has a for-and-aft sail. The mizzenmast, by contrast only carries a fore-and-aft sail and no square sails.
Beagle only sailed once as a brig. Two months after she was launched at Woolwich Dockyard on 11th May, 1820, she sailed up the River Thames to take part in a naval precession in celebration of the coronation of King George IV. In so doing, she became the first man-of-war to pass fully rigged under the old London Bridge. After the celebrations, however, she was held in reserve—or in ordinary, as naval parlance has it—for the next five years.
In preparation for her first commission in 1825, Beagle returned to Woolwich to be re-rigged as a bark. The addition of a mizzenmast would make her more manoeuvrable, and enable her to sail closer to the wind—vital modifications for a ship which would soon be surveying the intricate and dangerous islands and channels of Tierra del Fuego. At the same time, a poop cabin was added to provide much-needed additional storage space, and to house a large charting table. It was this cabin that would house Charles Darwin and his cabin-mate John Lort Stokes during the second Beagle voyage several years later.
© Dr Gordon Chancellor and reproduced with his kind permission.
The addition of a poop cabin had a secondary benefit which was, in many ways, more important than its primary one: it added height to the stern of the ship, giving greater protection against heavy seas, and enabling the decks to drain more quickly. Unmodified ten-gun brigs had a reputation for foundering in heavy seas, earning them the alarming nickname of coffin brigs.