Most large submarines consist of a cylindrical body with hemispherical (or conical) ends and a vertical structure, usually located amidships, which houses communications and sensing devices as well as periscopes. In modern submarines, this structure is the "sail" in American usage and "fin" in European usage. A "conning tower" was a feature of earlier designs: a separate pressure hull above the main body of the boat that allowed the use of shorter periscopes. There is a propeller (or pump jet) at the rear, and various hydrodynamic control fins. Smaller, deep-diving and specialty submarines may deviate significantly from this traditional layout. Submarines use diving planes and also change the amount of water and air in ballast tanks to change buoyancy for submerging and surfacing.

https://en.wikipedia.org/wiki/Submarine

Torpedo tubes are located amidships to accomodate the bow-mounted sonar. The sail-mounted dive planes rotate to a vertical position for breaking through the ice when surfacing in Arctic regions.

https://fas.org/man/dod-101/sys/ship/ssn-637.htm

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Note added at 18 mins (2019-08-28 17:04:45 GMT)
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The conning tower is about amidships and appears in two steps. From the deck to the top of the conning tower is about 12 feet. Two guns are mounted on the superstructure deck, one forward and one aft. These guns are short and of about 3 to 4 inches in caliber. From the bow to the stern, leading over the top of the conning tower, are two stout wires used both as short range radio wires and as protection against drags and nets.

https://maritime.org/doc/sub1917/index.htm

Term: amidships (adv)
Definition: At or toward the part of a ship halfway between the bow and stern; the middle, or waist; as in: The cat likes to sleep on the hatch cover amidships.
See Also: midships

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