At first it was believed that Captain Flinders would be placed in charge of her, but he was eventually given a more important command, and Lieutenant James Grant was appointed to the Lady Nelson.

She was hauled out of Deadman's Dock into the river on January 13th, 1800, with her full complement of men and stores on board.

She carried provisions for 15 men for a period of nine months, and enough water for three months.

Her armament consisted of only two brass carriage-guns.
On January 16th she sailed to Gravesend.

So small did she look as she made her way down the Thames that the sailors on board the ships in the river ridiculed her appearance and ironically christened her "His Majesty's Tinderbox." Grant says that many expressed a doubt that she would ever make her port of destination.
A heavy gale was blowing when she reached the Downs, but from the first she proved herself a good sea-boat, and it was found that lowering the keels greatly steadied her.