Of the SWAN not much I known, there were two ships with the name SWAN used by Drake and the sources sometimes mix up the two. .
Drake used a SWAN (1) on his early expeditions to the West Indies, so far not depict on a stamp.
He made two voyages to the West Indies, in 1570 and 1571, of which little is known, the vessel used was the SWAN (1) a flyboat of 50 tons. https://en.wikipedia.org/wiki/Flyboat
In 1572, he embarked on his first major independent enterprise. He planned an attack on the Isthmus of Panama, known to the Spanish as Tierra Firme and the English as the Spanish Main. This was the point at which the silver and gold treasure of Peru had to be landed and sent overland to the Caribbean Sea, where galleons from Spain would pick it up at the town of Nombre de Dios. Drake left Plymouth on 24 May 1572, with a crew of 73 men in two small vessels, the PASCHA (70 tons) and the SWAN (1) (25 tons? ), to capture Nombre de Dios.
His first raid was late in July 1572. Drake and his men captured the town and its treasure. When his men noticed that Drake was bleeding profusely from a wound, they insisted on withdrawing to save his life and left the treasure. He recovered but did not have sufficient men to crew both ships and three pinnaces, he decided to abandon the SWAN (1), she was set on fire.
Drake marauding for almost one year the coast of Panama before he sailed home with his loot, Arrived Plymouth 09 August 1573.
SWAN (2) depict on the British Virgin Island stamp. Where and when built I could not find.
It is given she was a flyboat of 25 ton, armed with 5 guns. And she sailed with Drake’s fleet on 15 November 1577 from Plymouth under command of John Chester.
She was abandoned due to not sufficient men to man the other ships of the fleet at Puerto San Julián, Patagonia on 17 August 1578. Other sources give that she was broken up on the coast of Argentina, and her useable parts divided across the other ships of the fleet.
British Virgin Islands 1887 40c sg981, scott876f.
Source: https://en.wikipedia.org/wiki/Francis_Drake