He was a pioneer of the riverboat industry on the River Murray and represented the Electoral district of Gumeracha in the South Australian House of Assembly from 1893 to 1899.

They had 9 children: As well as his mill management duties, William Randell assisted his father and brothers with their vast property which stretched from present-day Gumeracha to the River Murray.

His duties often involved droving cattle to the banks of the lower Murray, and dreamt of steam-boats being able to transport produce between South Australia and the neighbouring colony of Victoria.

In 1852, with no experience in the steamboat construction, Randell commissioned local carpenters to build the frame of a 55-foot-long (17 m), 9-foot beam (2.7 m) paddlewheel boat of shallow draught, capacity 20 ton in Gumeracha.

Named the Mary Ann, after his mother, the steamer featured a 10-inch bore (250 mm) cylinder beam-engine delivering 8 horsepower, made by a German engineer from Adelaide, Carl Gehlkin.

[12] Randell abandoned Noa No as too subject to flooding and built a small "pug and pine" cottage, the start of the town of Mannum, and a dry-dock.

His second boat, the twin-hulled single paddle-wheel "Gemini", despite its small size and ungainly appearance, managed some feats of navigation into New South Wales.

[2][13] Randell built (or commissioned) many more steamers: "Bogan", "Bunyip" (destroyed by fire in 1863,[1] along with its barges), "Ariel", "Nil Desperandum", "Corowa", "Waragery", "Tyro", and "Ruby".