MV Amastra was one of nine Anglo-Saxon Royal Dutch/Shell oil tankers converted to become a Merchant Aircraft Carrier (MAC ship).

MV Amastra was built at Lithgows and completed in March, 1935 as an oil tanker for the Royal Dutch/Shell line.

She was converted at Smiths Dock, North Shields to a MAC ship, entering service in September 1943.

[1] As a MAC ship, she had no aircraft hangar, and continued to carry cargo, although operating under Royal Navy control.

[2] At the end of the war, Amastra was reconverted to an oil tanker, and in 1951 was renamed Idas.