page_title: Prestonian-class frigate
section_title: Modifications
hierarchical_section_title: Prestonian-class frigate / Modifications
caption_attribution_description: HMCS Toronto K538 WW2 River Class Frigate
context_page_description: The Prestonian-class ocean anti-submarine escort frigate was a class of 21 frigates that served with the Royal Canadian Navy from 1953–1967 and with the Royal Norwegian Navy from 1956–1977.
  They were converted from mothballed River-class frigates of British design that had been placed in reserve following the end of the Second World War. The first vessel to be reactivated and undergo refit was Prestonian which was recommissioned on 28 August 1953. The class did not use sequential pennant numbers.
context_section_description: The River-class frigate was a successful Canadian-built escort design from the Second World War, However, there was a requirement to update this design to meet the needs of the post-war Canadian Navy and to match the threat of the Soviet submarine force.
  The fo'c'sle deck was extended aft and was wall-sided. This extra space was primarily devoted to improved habitability. All accommodation throughout the ship was improved. Each crew member was given their own bunk. The space was also used for generating machinery required by for anti-submarine warfare. This machinery was changed from three steam and one diesel to two steam and two diesel generators. The quarterdeck was enclosed to house two Squid anti-submarine mortars.
  A much larger bridge structure was installed that was almost entirely enclosed. The upper works were constructed of aluminum instead of steel to save weight. This necessitated a heightened funnel to clear the new structure, which in turn required a larger mast. This mast remained a tripod. The propelling machinery was overhauled and the hull forward was strengthened forward to protect against ice. 
  One ship, Buckingham, had a flight deck attached aft for helicopter landing and takeoff sea trials, but the structure was removed once the trials were completed.
caption: HMCS Toronto prior to modification – note the lower deck aft
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