6) the kingstons in the main ballast tanks, except for the midship group, and also the negative tank and fuel-ballast tanks not filled with fuel;

7) the snorkel kingston;

8) the voice tube valve, connecting the control room with the bridge. The following remain closed:

1) kingstons in the midship tanks;1

2) main ballast tank and buoyancy tank vents.
When a submarine is operating in diving trim, the following remain open:

1) conning tower hatch;
2) diesel main air induction;

3) cooled air exhaust valve and valve of the main electric motors; the pressure compensation valves in the fuel tanks;

4) engine room kingston gas exhaust and cool water exhaust, but only when the diesels are operating;

5) snorkel kingston;
6) kingston when the main ballast tanks are filled;

7) the ship and battery ventilating shafts, by special order of the Commanding Officer of the submarine and only during ventilation;

8) voice tube kingston.
When the submarine is in diving trim the following must be closed:

1) the kingstons in midship main ballast tanks, negative tank and fuel-ballast tanks when they contain fuel;

2) the vents in all the main ballast tanks, negative tank and fuel-ballast tanks;

3) the buoyancy tank vent.
The following must be open while submerged:

1) the main ballast tank kingstons, except for those filled with fuel;

2) the pressure compensation valves in the outboard fuel tanks and the main ballast tanks filled with fuel;

3) the buoyancy tank vent;
4) the engine room kingston and diesel exhaust valves; snorkel


and air exhausts when the submarine is snorkeling;

5) the snorkel kingston;

6) the cooling water discharge valves from the line shaft, but only when the circulating pump is operating. When the submarine is submerged the following must be closed:

1) the vents in all of the main ballast tanks;

2) the negative tank vent and kingston. Whenever the submarine is under way the bulkhead doors must be closed with the rack mechanism. Deviation from this regulation is permitted only when the diesels and ventilation are operating and when there is circulation of air between compartments while submerged, at which time the bulkheads may be open.

The main ballast, as well as the fuel-ballast tanks when they contain fuel.

The high-pressure air system should be ready to blow the main ballast tanks, and the kingston and tank vent hydraulic drives should be ready for immediate use at all times.

2. Handling a Submarine Surfaced

After surfacing, if the situation permits, the vertical rudder is controlled from the bridge (conning tower) and control of the engine order telegraph is shifted to the conning tower by giving the commands “Rudder control to the bridge (or conning tower)” and “Control of the engine order telegraph to the conning tower.”

In order to prepare the diesels for propulsion operation, the command “Prepare such and such a diesel for propulsion operation” is given. The next step after preparing the diesel is given by the command “Such and such a diesel, low speed."

A twin-screw submarine with all engines going ahead answers the helm well. With one engine going ahead, the submarine turns faster and with a smaller final diameter on the side opposite that of the operating engine.

Going astern, the submarine answers the helm poorly and is kept on course only with the help of the engines. A submarine going astern answers the helm only with the engines stopped and when there is considerable inertia.

In order to turn on her heel, the engines must be operated in different directions: the outboard engine ahead, and the inboard astern with the rudder hard over in the direction of the turn.

In order to turn on her heel with a wind force of 4-5, the engines must be worked in different directions at moderate speeds.

Various classes of submarines operating at full buoyancy in stormy weather have a tendency to be buried in the wave.

In a heavy sea the best courses are heading into the sea, running with the sea or close to these (up to 30°).

If waves flood the bridge and a considerable amount of water gets into the control room, and if the superstructure fails, the speed must be reduced. Personnel standing watch on the bridge must be protected against the storm.

When a submarine is surfaced personnel may go on top deck only with permission of the Commanding Officer. Each man going on deck must wear a life jacket and tie himself to a safety line.

At sea, hull openings may be opened and machinery started up only by order of the Commanding Officer (or officer of the watch). In unusual circumstances a special watch is mounted at the operating gear of open wells and hatches by the Commanding Officer (officer of the watch).

At sea, articles of clothing, binoculars, etc. may not be hung up on the bridge, or lines and cables extended through the conning tower hatch. The bridge must always be rigged for a crash dive.

The maneuvering and seakeeping qualities of submarines in diving trim are not quite as good as in full buoyancy. Under way, and especially in a wave, submarines tend to bury their nose in water, and in turning they assume a trim by the stern with part of the after section of the supersturcture submerging.

While operating in diving trim, the trim should be closely observed. If the submarine tends to bury its nose in the water, either the speed must be reduced or the fore and aft tanks blown and discontinue proceeding in diving trim.

The transition from full buoyancy to diving trim must be made without a way on or at low speed using the electric motors. But first unnecessary personnel must be removed from the bridge, the negative tank blown, stern planes set for surfacing, the general alarm sounded and be ready to dog down the conning tower hatch.

Shifting from full buoyancy to diving trim with the diesels operating and the wells open is categorically prohibited.

3. Trimming

The following requirements must be met in trimming a submarine:

1) the residual buoyancy of the submarine must be equal to zero or close to it;

2) there must be a trim by the head of not more than 0.5-2°, with each trim tank filled to one-half to three-fourths of capacity, making it possible to adjust the trim of the submarine under all submerged operating conditions;

3) trimming should be stable for the established submerged operating conditions throughout the duration of one watch (4 hours) and adjustment of the stern planes must not exceed 15° with the bow planes in the plane of the frame;

4) after surfacing, if it becomes necessary to resubmerge within a short time, the submarine should freely maneuver under water without adjusting the trim.

Trimming without a way on. Before trimming, the level of the main drain is checked. If the torpedo tubes are empty, they must be filled with water, which must be taken into account in calculating the trim. If there is any doubt concerning the accuracy of the calculated trim, 1-5 tons less than the calculated amount of water is taken into the negative tank.

Before main ballast is taken on, the command “Trim the submarine at a depth of so many meters, without a way on, with a trim of so many degrees by the head (or stern)” is given.

In trimming a submarine, it is particularly important to adjust the trim, then buoyancy, within required limits. The required buoyancy is achieved by taking water into the auxiliary tank or pumping it overboard, while the trim is equalized by pumping water from the auxiliary tank into the trimming tanks or by pumping it from one trim tank into another.

With a high positive buoyancy, water is taken into the auxiliary tank through its sea cock, and with a low positive buoyancy it is admitted through the fine flooding valve.

If with the midship tanks un filled, the trim exceeds 0.5°, it must be reduced to zero, since in the opposite case, with the midship tanks filled, it increases significantly.

As the midship tanks fill up, their ventilating system is closed immediately. If as the midship tanks fill up, the submarine acquires a significant negative buoyancy or a trim of 5-10° and more, a bubble must be introduced into the midship tanks and the required quantity of water pumped out of the auxiliary tank, then, removing the bubble from the midship tanks, continue trimming.

After trimming is completed, the main ballast tank vents are closed, after which the compartment heads report to the control room on the presence of personnel in the compartments and the quantity of water in the auxiliary ballast tanks. This information is recorded in the deck and trim logs.

If before trimming, the annular spaces of the torpedo tubes were not filled with water from the water-round torpedo tanks, then after trimming is completed the quantity of water in these tanks must at least equal the quantity required to fill the annular spaces.

Trimming under way. In a calm sea, a submarine can be trimmed at periscope depth, and in a rough sea at safe depth. Before diving, the command “Proceed to your stations, prepare to dive” is given. After the men have taken their stations in accordance with the diving procedure, the conning tower hatch is dogged down, the electric motors started and main ballast taken on. After ballast has been taken on, the order “Trim the submarine at a depth of so many meters, with such and such a way, with a trim of so many degrees by the head (or stern)” is given.

Main ballast is taken on the same as in trimming without a way on. The midship tank vents are closed immediately after the tanks are filled.

The indicated trimming depth is maintained by the way and trim. There is no need to develop a large trim in diving. The main ballast tank vents are closed immediately after the submarine attains the ordered depth, after changing the trim from the head to the stern.

If the submarine does not dive, water must be taken into the auxiliary tank through the kingston or the fine flooding valve. As soon as the depth gauge indicates a change in depth the water in take is shut off.

If after filling the midship tanks the submarine acquires negative buoyancy, the submarine must be trimmed by the stern by means of the rudders and way and, while maintaining the ordered depth, water must be simultaneously pumped out of the auxiliary tank.

If these measures are inadequate, a bubble is admitted to the midship tanks or they are blown, or the required amount of water is pumped out of the negative tank and then, removing the bubble from the midship tanks, trimming is continued. These measures are taken depending upon the rate of change in the depth of the submarine.

Air bubbles must be removed from the forward and after main ballast tanks and from the superstructure by alternately trimming the submarine by the head

and by the stern ("rocking” the submarine), after which the main ballast tank fore and aft vents are closed.

Through drainage or taking water into the auxiliary tank and by pumping the auxiliary ballast between the trimming tanks, the bow planes are adjusted to zero position and the stern planes with a slight deviation from the plane of the frame, and the submarine maintains its depth with a slight trim by the head. In this position the submarine is considered trimmed.

After the submarine is trimmed, the midship tank vents are opened to remove the residual air bubble, then these vents are closed. The submarine is maintained for awhile with a trim of zero degrees and the command “Trimming completed” is given. With this command, the compartments report to the control room on the presence of personnel in said compartments and the quantity of water in the auxiliary ballast tanks, and appropriate entries are made in the deck and trim logs.

4. Controlling the Diving Planes in Event of a Crash Dive

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With the command “All hands below,” all hands on the bridge (on the deck and in the superstructure) quickly go below.

With the “Crash dive” alarm, the deck watch quickly goes below (if the command "All hands below,” has not been given), and the submarine crew simultaneously takes the following measures:

1) stops the diesels; disengages the forward clutches; dogs down the diesel air main induction inlets and other hull openings; opens the MBT pressure equalizing valves containing fuel, and also the buoyancy tank vent;

2) starts the electric motors;
3) fills the main ballast tanks;
4) controls the diving planes;
5) blows the negative tank and closes its kingstons;

6) closes vents in the midship tanks and main ballast tanks. In crash diving, the midship tanks are filled after the conning tower hatch is dogged down and after the monitoring instrument on the control panel indicates that the conning tower hatch, the diesel main air induction and the ship and battery vents are closed.

In the initial stage of diving, the bow planes must be set for diving and the stern planes for surfacing. In this case, both pairs of diving planes create downward forces. The stern planes, which create a trimming moment by the stern, enable the submarine to remain on an even keel, equalizing the trimming moment which occurs when the negative tank is filled.

In attaining depth, when all of the main ballast tanks are filled, the planes must be set for diving, a trim of up to 10° (depending on the class of submarine) must be created, and must be maintained during diving.

If the submarine must remain at periscope depth, the negative tank is blown at half the periscope depth and, if need be, the submarine dives to a depth where it is safe from ramming-a depth not less than periscope depth.

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