Conning Tower

If the Control Room is the "brain" of a Guppy submarine, the Conning Tower or "Con" is the aggression center of that brain. It is an 8-foot diameter, 17-foot long cylinder with rounded ends lying on its side above the after end of the Control Room.

Conning Tower below the Bridge, above the Control Room inside the bridge fairwater or ’sail’.Conning Tower below the Bridge, above the Control Room inside the bridge fairwater or ’sail’.

In the Con’s forward end a starboard side hatch in the overhead leads up to the bridge. In the floor on the port side, just behind the where the helmsman stands to steer the boat, is another oval hatch dropping down to the Control Room.

Steering stand and bridge access hatch.Steering stand and bridge access hatch.

Control Room access hatch.Control Room access hatch.

The "Con" contains the eyes, ears, calculator and triggers for navigating, tracking, planning and shooting torpedoes at targets.

After CUBERA’s Guppy-II conversion --

Forward to aft, starboard side:

Forward to aft, port side:

Center, fwd-to-aft:

Here’s the layout, as I remember it:

Conning Tower layout of Cubera after GuppyII conversion.Conning Tower layout of Cubera after GuppyII conversion.

Of course, the cork-covered walls and nooks and crannies are also filled with the usual conduits, switches, air ducts, emergency lights, pressure gages, intercom speakers, hydraulic and air lines, junction boxes and storage lockers, too. The original SONAR gear was removed and updated gear installed in a newly added small ’shack’ in port aft end of the forward torpedo room. A new SS-1 RADAR and more compact PPI console replaced the old WWII SJ.

Ignoring variations among submarine types and individual command practices, conventional submarine torpedo attacks against surface vessels proceed along these lines:

Target Attack Approach

When a target is sighted, the battle stations fire control team begins plotting using the #2 periscope bearings and ranges. This scope has larger lenses and optical path for distant obervations. Ideally, the target is heading toward the sub, its range ever decreasing. An attack from a point aft of the target can necessitate an hours-long race to get ahead and into a waiting position of ambush. In any case, RADAR and periscope observations establish the target’s course and speed which are tracked within the TDC and by hand on the wardroom plotting table in the Forward Battery. The manual plot is a backup in case the TDC fails. Continuous real-time inputs from the sub’s speed pit log and gyro compass to both the TDC and manual plot table keep its track relative to the target updated. Those signals move a lighted "bug" under the clear plastic surface of the table. The plotting team traces its path on a sheet of paper taped above the plastic table top, along with the target information passed down via the battle stations sound-powered phone circuit from the Con. An elegant trigonometric dance ensues to develop necessary answers to two questions: At what target bearing and distance do we fire? What is the torpedo speed and track angle required?. The paper plot of this "firing solution" becomes the historical record of the attack.

Example approach plot by periscope stadimeter (distance by height device).Example approach plot by periscope stadimeter (distance by height device).

During the attack phase, the thinner #2 scope is used. It’s head diameter is just 1.414 inches (coincidentally, that’s the squareroot of 2), and produces a smaller wake, allowing higher speeds near the target. Assuming all tubes are loaded, at some time near the end of the approach, when the attack team is confident a firing is imminent, the order "Prepare to fire tubes (forward or aft)" is passed over the sound-powered phones circuit. The torpedo room crew charges the impulse air flasks with up to 600 psi from the main high pressure air banks. They also insert the gyro angle-setting spindles into the loaded torpedoes, and prime the firing pilot valves.

Of course, this process as described simply here has only ever been used in peacetime and during the early years of the Cold War during anti submarine warfare (ASW) training exercises. But the methods thus developed were subsequently incorporated into the computer software used in present day advanced strategic submarine weapon fire control systems.

Torpedo status and fire control panels of the USS COD.Torpedo status and fire control panels of the USS COD.

Torpedo Fire Control

Each of the Fwd and Aft torpedo status/selector panels have two rows of status lights, above a row of selector switches. All switches are initially in their vertical or "Off" positions. Mechanically interlocked, only one switch can be in the horizontal or "Standby" position at a time. The top row lights are on when the torpedo tube gyro setting spindles are inserted. When the angles are matched to the angle predicted by the TDC, the spindles are retracted, the upper lights go out and the lower "Ready" lights come on. Either to the side or above the panels are the forward and aft palm-sized torpedo firing keys.

When the firing solution bearing and range to target is reached, the panel operator rotates the ordered torpedo selector switch to "Standby". In the torpedo room, the corresponding "Standby" light tells the torpedoman to prepare for the firing sequence. He opens the poppet valve drain valve, sets the automatic vent-closing valve lever to "On" and moves the tube firing interlock lever to the "Ready" position. The tubes "Ready" light in the Con comes on. The TDC is still continuously updating the torpedo’s gyro angle.

At firing point, the Captain gives the "Fire!" order. The Con fire control operator presses the firing key, applying 120VDC through the selector switch and the torpedo spindle interlock switch at the tube to the remote firing solenoid. The firing solenoid, operating through interlocking mechanisms, retracts the gyro spindle and opens the pilot valve. 200lb pilot air operates the firing valve and applies 600lb impulse flask air that starts the torpedo out the tube.

Inside the muzzle end of the tube, the starting lever fires the igniter to start the torpedo’s alcohol and hydrogen peroxide-powered steam engine which quickly spins up the drive turbine, spinning the counter rotating propellers pushing the fish on its way. Actuated by a roller at the breech end following down the taper of the fish’s afterbody, the tube’s poppet valve trips in seconds, capturing the air bubble internally before it can exit the tube and betray the boat’s position.

Within a few tens of yards, the torpedo swings to its preset gyro deflection angle, levels at its running depth and races toward its deadly explosive rendezvous with the doomed and blissfully oblivious target vessel. The turning radius has been accounted for in the TDC calculations.

Sometimes it takes two shots...Sometimes it takes two shots...

Meanwhile, a few seconds after firing, the torpedoman manually shuts the poppet valve drain to prevent excess in-rushing sea water from flooding the drain tank under the floor. The water in the tube and drain tank compensates for the lost weight of the torpedo’s exit, maintaining the boat’s trim. The torpedo room crew either prepares the tube for a subsequent reload or may ready another tube for firing, depending on orders from the Con.

Lather, rinse, repeat... sorry, drain, reload, repeat.

(Background image: Conning Tower of the USS POMPANITO.)


Last modified: 15Mar2020