This plan contains a diagram for setting up the rigging of the Admiralty trawlers such as TR4.&The plan for the vessel was based on a design produced by Smith Dock Company of Middlesbrough in early 1916. The Port Arthur Shipbuilding Co. Ltd. of Port Arthur, Ontario, used the plan to build 60 trawlers under contracts overseen by the Royal Canadian Navy.In the top right-hand corner of the plan it also notes the number of items required to be ordered from the Boston and Lockport Block Company. Since the mid-nineteenth century, the company had traded at 210 Market Street, Lockport, New York. However, two catastrophic fires would eventually cause it to close. Source:Great Lakes Marine Archives ship plan collection / [compiled by] Dave Benedet. Thunder Bay Public Library, Ontario, 2011.