MV Acavus was a motor tanker that was built in 1935, and converted into a merchant aircraft carrier (MAC) in 1943. She was built for Anglo-Saxon Petroleum, which is part of Royal Dutch Shell. In 1952 she was transferred to a French subsidiary of Shell and renamed Iacra. She was scrapped in France in 1963.
Acavus was the last ship ever built by Workman, Clark and Company. The company was founded in 1879, and went into receivership in May 1935, about four months after completing Acavus.
Building and registration
In the 1930s, Shell ordered a series of oil tankers called the "Triple Twelve class" from various shipyards. Workman, Clark built one member of the class. She was built as yard number 536; launched on 24 November 1934; and completed in January 1935. She was named after the Acavus genus of land snails. Her registered length was ; her beam was ; her depth was ; and her draught was . Her tonnages were and . She had a raked bow and a cruiser stern. Her main superstructure, including her bridge, was amidships. Her engine room and single funnel were aft.
Tankers were a priority for conversion into defensively equipped merchant ships. Primary armament for a ship such as Acavus was a single 4-inch (102 mm) gun mounted on her poop deck, for defence against surface ships and submarines.
thumb|A [[Fairey Swordfish on the flight deck of an aircraft carrier]]
Between 1942 and 1944, nine of Shell's Triple Twelve class tankers were converted into MAC's. Silley, Cox & Co of Falmouth, Cornwall converted Acavus, fitting her out with a flight deck long by wide. She had no aircraft hangar or aircraft lift, but could carry three Fairey Swordfish torpedo bombers. Her armament was augmented with eight anti-aircraft guns: two Bofors 40mm autocannon and six Oerlikon 20 mm cannon. After conversion, her length overall was , and her beam was . Her displacement was full load, and standard.
As an MAC, Acavus continued to carry cargoes of oil. The conversion reduced her capacity by about 10 percent, and she was restricted to crude oil to reduce the fire hazard. She remained a Merchant Navy ship with civilian crew, but with the addition of Royal Navy aircrew and aircraft maintenance crew. She entered service as an MAC in October 1943. In 1945 or 1956 her flight deck was removed, and she was converted back into a conventional oil tanker.