 Fredericton was part of the Revised Flower class built between 1940 and 1941 . There were 10 ships in this class including HMCS Calgary , HMCS Charlottetown and HMCS Halifax . Improvements on the original design included a lengthened forecastle and the foremast was moved behind the main bridge to improve forward vision . The sheer and flare of the bow was increased to improve performance in heavy seas . Earlier Flowers had twin 0 @.@ 5 inches ( 12 @.@ 7 mm ) machine guns , which proved ineffective . The revised Flowers were built with single Oerlikon 20 mm ( 0 @.@ 8 in ) cannon mounted on either side of the bridge . 
