NEXT week the Royal Navy is moving its naval base HMS Tamar in Central to Stonecutters Island. HMS Tamar was named after an old warship built in London in 1863. She arrived in Hongkong waters in 1901. She was the fourth ship to bear that name. The first HMS Tamar was a 16-gun sloop of 313 tons, built at Saltash on the River Tamar, which marks the boundary between the counties of Devon and Cornwall, in the west of England. Hongkong's HMS Tamar became the Royal Navy's Depot Ship soon after her arrival in the colony. This involved turning her into a hulk by trimming her masts and roofing over her decks. In the early days, hulks were used as hospital ships, prison ships, floating warehouses, even factories - and there were plenty of opium hulks. These mutilated vessels littered Victoria Harbour. Typical of these floating cripples was the hulk Jay, which had a sign on the side advertising a composition for slapping on ship's bottoms called the ''Red Hand Brand.'' She was a popular butt for slightly vulgar Victorian jokes. Hongkong wits also had abit more fun at the expense of her owners who manufactured and marketed soap under the unsuitable trade name of F. Blackhead and Co. Blackheads is a vile skin complaint - a small lump blocking your follicles. HMS Tamar was the nearest any of the hulks came to being elegant. She had a slim line and a splendidly carved mermaid as a figurehead. For 40 years she lay at anchor in the centre of Victoria Harbour. World War II was her Nemesis. During the Battle for Hongkong in 1941, the Royal Navy scuttled the grand old ship to save her from the humiliation of falling into enemy hands. The exact location of the wreck is unknown. Legend has it that it is in Lamma Channel. To call a dockyard, a group of buildings or even a solitary Nissen hut, a ship, is one of the strange traditions of the Royal Navy. Consequently, after World War II, what was left of the Royal Naval dockyard in Central became known, in 1945, as His Majesty's Ship Tamar - the fifth of that name. The first Tamar had as bizarre a history as any of her successors. In 1764, the British Admiralty sent Commodore the Honourable John Byron in two ships, one of which was the Tamar, to search for ''Land or Islands of Great Extent, hitherto unvisited . . .between Cape Horn and New Zealand.' Commodore Byron was known as ''Foul-Weather Jack.'' He was the grandfather of poet Lord Byron. Lady Caroline Lamb described his grandson as ''mad, bad and dangerous to know.'' This epithet could equally be applied to ''Foul-Weather Jack,'' who was also anotorious womaniser and libertine. Byron's little squadron first visited Patagonia, named by the Spaniards after the Patagonians, who inhabited the barren southern part of what is now Argentina. They were a noble race of large people who had enormous feet. Byron described these giants as behemoths, who made a six-foot-two British sailor appear like a mere shrimp when standing beside one of these creatures. His next stop was the Falkland Islands. The British Captain John Strong was the first person to land there in 1690. Byron staked out the British claim to the Falklands by raising the Union Jack and planting a small vegetable patch which he called rather grandly, Port Egmont. Two years later, the British sent a force to kick out the French who had established a settlement on those troubled islands. Byron's ships passed through the Magellan Strait and into the vastness of the the Pacific Ocean. Byron went nowhere near New Zealand, but took a north-westerly course across the Pacific. It was an uneventful voyage. All he discovered were seven obscure islands including, Danger, Disappointment and a group which he modestly named the Byron Islands after himself. He was also meant to search for a northern passage into the Pacific, but he didn't bother. ''Foul-Weather Jack'' seemed to be more interested in getting home to the flesh-pots of London, than exploring. His hurried circumnavigation of the globe did not endear him to the British Admiralty. They had to send out Captain Cook a few years later, todo the job properly. The sixth HMS Tamar is now being built on Stonecutters Island, thus guaranteeing that the illustrious name will live on at least until 1997. One can only speculate where - or what - will be the seventh ship of the line. Unfortunately nowadays the Royal Navy seem to have more names than they have ships.