Sirius, commanded by Captain John Hunter, was the flagship of the First Fleet, which under Commodore Arthur Phillip transported convicts from England to New South Wales in Australia.
Raper's charts, and his paintings of ports such as Tenerife and Rio de Janeiro, were part of his evidence of competence for his promotion to midshipman.
On 1 October 1788, Sirius with Raper on board set sail from Port Jackson for the Dutch settlement of Cape Town, to get supplies for the starving Australian colony.
On the return to Port Jackson, Sirius suffered damage in a gale off the south coast of Van Diemen's Land.
He and the crew of Sirius were trapped on the island for 11 months, facing starvation and increasing distress at the failure of Governor Phillip to send a ship to collect them.
[2] Back in England, the officers of Sirius, including Raper, faced a court martial because of the loss of the ship.
Only two paintings that can be dated to his period of service in the Mediterranean are known to have survived – they are of a dolphin and a shark, and are held at the State Library of New South Wales.
[3] There are reports of multiple deaths from fever on Royal Navy vessels in the West Indies in the preceding months.