New British Amphibian Biplane Sea Otter Mark I. The Sea Otter I in flight. The Vickers Armstrong Supermarine Sea Otter Mark I is a single-engined amphibian biplane designed for naval spotting, reconnaissance and general-purpose duties. It is also engaged on Air/Sea Rescue. It has catapult equipment, and is powered with a Bristol Mercury 30 engine of 870 m.h.p., driving a ***** three-blade variable pitch constant speed propeller. The main planes are made to fold and the land under-carriage is ret