Scale 1:48. Plan shows the inboard profile and topsides, as fitted, of the M-class submarine M3 (1919). The drawing shows the bridge, the top of the superstructure and the outer hull. The plan also shows modifications in vermillion ink made at Chatham Yard, dated January 1929. A note on the plan states to see the fly diagram for the minelayer arrangement. There is a Armstrong & Whitworth Naval yard stamp dated 16 February 1921 on the left hand side of the plan. A second Admiralty stamp bearing the signature of the Ship Overseer "T. H. Bentley", dated 5 September 1921 is situated undeneath the first stamp.