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Saturday 6 February 2016

Preliminary design for an American armoured cruiser submarine type 2 dated 23 October 1920


Drawing S 584-166 made after a request of the Chief of the Bureau of Construction and Repair done in early October 1920. Despite an armour weighting 474 tons was this type not built regarded as very vulnerable to torpedo attacks due to lacking sufficient side protection.

With a displacement of 13.500 (normal ready to dive) tons and as dimensions 490’0” (over all) x 60.0” (extreme on waterline) x 29’0”, Freeboard maximum at stem 16’0”m at A.P. 8’0” and a freeboard at side M.P. of 8’0”. Total depth at M.P. measured of uppermost strength D.K. 37’0”. To be fitted out with 8-1.100 shp diesels driving generators and 4 main driving motors. Speed 15,5 knots and a range of 20.000 nautical miles with a speed of 10 knots. The armament consisted of 808” guns, 2-4” anti aircraft guns and 8-21” torpedo tubes (bow 6 and stern 2). The main side belt armour stretched 5’0” below the waterline with a thickness of 90≠over 40≠. The turrets were protected by armour with as thickness sides and rear 2”, top 3” and port 6”. The coning tower was protected by 6” although the top was just 3”thick. Total thickness of protective deck 90*. Coefficients at normal displacement longitudinal .616, block .554, midship .908 and displacement-length 115. Displacement normal condition ready to drive 13.500 ton: hull ordinary 5.000 ton, deck protection 1.150 ton, protection conning tower and guns 474 ton, armament 431 ton, ammunition 275 ton, equipment 200 ton, outfit and stores 500 ton, water in auxiliary tanks and others 300 ton, fuel oil full supply 1.350 ton, margin 600 ton and lead ballast 500 ton.

Source the so-called Spring Styles Book 1 (March 1911-September 1925). Naval History and Heritage Command. Lot S-584. Preliminary designs prepared by mostly civilians working at the Bureau of Construction and Repair (succeeded by the Bureau of Ships nowadays the Naval Sea Systems Command) under supervision of naval architects of the Navy Construction Corps. A major part of the drawings is presented to the General Board which adviced the Secretary of the Navy.