planes. Having begun to pump water, the diving planes must be eased, at the same time varying the quantity of water in the compensating tank.

3. Using the Diving Planes Together

1. A submarine is proceeding at constant depth H = const, with trim ↓ = 0; bow and stern planes in different directions at 8 = 85 (Fig. 14).

S

The submarine is heavy and possesses an unbalanced trimming moment by the stern. In order to trim the submarine, ballast must be pumped from the compensating tank and water pumped from the after trim tank into the forward trim tank. In beginning to pump water from the after trim tank into the forward trim tank, the bow planes must be eased, then ease the stern planes after they assume a neutral position, while simultaneously pumping water from the compensating tank.

=

2. The submarine is proceeding at constant depth H1 = const, with trim ↓ = 3-4°, bow and stern planes are positioned in different directions at = 8, (Fig. 15).

The submarine is light and possesses an unbalanced moment at the stern. In order to balance the submarine, ballast must be taken into the compensating tank and water pumped from the after trim tank into the forward trim tank.

4. Hydrodynamic Force on the Hull

No matter how well trimmed a submarine is, trims develop when it moves. This proceeds from the fact that a submarine is unsymmetrical with respect to the horizontal plane. The resultant of the hydrodynamic forces of the hull R' acts at a certain angle to the rate of linear displacement of the center of gravity. The point of application of the resultant of the hydrodynamic hull forces O is called the center of pressure and is forward of the center of gravity (Fig. 16).

Let us divide the hydrodynamic hull force into vertical and horizontal components. The horizontal component R will be compensated by the thrust of the propeller, while the vertical component R', creates a lifting force.

In order to determine the effect of the hydrodynamic force, we make the following constructions.

At the center of gravity of the submarine we apply the vertical component R,, acting in the opposite direction. A hydrodynamic moment results, since the resultant applied at the center of pressure O does not coincide with the center of gravity G.

When a submarine is operating with full buoyancy the following remain

open:

1) the conning tower hatch;

2) the diesel main air induction, engine room kingston and diesel exhaust valves, only when the diesels are operating;

3) the cooling water discharge valve and the valve of the main electric propulsion motors;

4) the pressure compensation valves in the fuel tanks;

5) the ship and battery ventilating shafts, by order and only during ventilation;

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;

tanks;

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

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 gas 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 ±5° 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.