 He attended Kirkwall Grammar School until he was 13, but was largely self-educated, learning much from Arthur Mee's "The Children's Encyclopædia".He worked in the family draper's business in Kirkwall.He joined the Royal Navy in 1916 and served in Scapa Flow during World War I.

Rendall, a man of many talents, known as a poet, and authority on shells, flowers, and marine life, has been described as an "Orcadian Renaissance man".