Written on the back of the painting's original backing: "The Kentucky was built in 1833 for Captain Benjamin Carver and was sailed by him for 10 to 12 years. She then went into the slave business, carrying slaves from Africa to Rio de Janeiro." According to Searsport Sea Captains by Frederick Black, the Kentucky was one of the fastest of her type in the world.
Ships, Barks, and Barkentines had 3 or 4 masts. Brigs and Brigantines had two. Sometimes schooners might have square topsails set on the foremast. But unlike these vessels, such a schooner would have a gaff foresail.
The diagram is from the Nova Scotia Museum Info poster, Sailing Ship Rigs.
Even though much of the wealth of Bristol and Liverpool merchants came from the slave trade, in 1807 the British Parliament outlawed it. This was at the height of the Napoleonic war, two years after Trafalgar. The Royal Navy was fully committed against the French. The Admiralty sent two warships to West Africa on anti-slavery patrol despite the fact that the war with France and then the United States demanded most of the Navy’s ships.
Salmon kept a catalogue of his paintings, numbering each painting and indicating where he was when it was painted. This is number 395 which, according to the catalogue, must have been second to last painting he did in 1823 in Liverpool, before he emigrated to Boston.