Lonsdale was one of several torpedo boats ordered by the government of Victoria in 1882 to protect the colony from a possible Russian or French attack, and was built by John I. Thornycroft & Company. The torpedo boat was long, with a draught of , and a displacement of 12.5 tons. She was designed with a low freeboard, to minimise her profile. The boat had a maximum speed of , which she would use to close rapidly with enemy vessels before attacking. Lonsdale was initially armed with two 14-inch torpedoes carried in bow recesses, and a spar torpedo, but in 1888, she was modified to carry the two 14-inch torpedoes in locally-developed 'dropping gear'; a davit-like device for lowering the torpedoes into the water for launching. She was also armed with 2 Hotchkiss machine guns.