Starting young at sea was not uncommon in most navies.
Lord Nelson was 13 when he went to sea for the first time,
Lord Collingwood was 12. John Paul Jones was 13 on his first voyage. Admiral David Farragut became a midshipmen at the tender age of 9. Admiral David Porter was 16 as was Admiral Yamamoto.
Robert Pitcairn was a 15-year-old midshipman when he spotted the island in the South Pacific which is named for him. He died in 1770. His father, Major John Pitcairn, commanded the British troops in the battle of Lexington on April 19, 1775, and was killed in the battle of Bunker Hill in June 1775.