PART 6. USEFUL INFORMATION AND DATA

CONTENTS

  Page
Chapter 1. Conditions of readiness of armament.- 20-mm. and .50-caliber B. A. gun data 89
Chapter 2. Fuel consumption and cruising radius tables- Submarine data tables- Radius of visibility of M. T. B. tables 95

CHAPTER 1. (A) ARMAMENT-CONDITIONS OF READINESS

6101. General.-During wartime there will be two conditions of readiness of the armament: Ready condition and fully ready condition. The armament may be in the ready condition when boats are under repair, secured, moored to a dock or on training runs when action with the enemy is not probable. On any occasion where action with the enemy is probable, the armament will be in the fully ready condition and partially or fully manned, depending on the circumstances and on the mission on which engaged. In placing the armament in the fully ready condition extreme care must be exercised inside the harbors or other areas where own or friendly vessels may be endangered by accidental discharge of weapons.

6102. Battle stations.

GENERAL QUARTER-CONDITION 1

Boat captain-Conn: Wheel or throttle.
Executive officer-Throttle or wheel.
GM-Oerlikon gun.
Tm-Stand by torpedoes or depth charges.
QM-Ammunition passer for .50-caliber guns.
RM-Radio.
MM-Engine room. MM-Starboard .50-caliber guns.
MM-Port .50-caliber guns.
Sea-Loader for Oerlikon-gun.

NOTE.-The above may and should be changed to utilize special aptitude or training of any man.

 
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CONDITION 2

Station Watch 1 Watch 2
Conn Captain Executive Officer.
Communications and navigation RM QM.
Wheel, torpedoes TM GM.
.50-caliber guns SC MM.
.50-caliber guns Sea  
Engine room M M M M.

6103. Torpedoes-Ready condition.

1. Preliminary and final adjustments.
2. Charged to between 2,000-2,800 lb. per sq. in.
3. Warhead attached, exploder and booster in.
4. Two brass stop pins in place.
5. Tubes trained in, not secured.
6. Firing keys in commanding officer's key locker.
7. Impulse charges in provided stowage.
8. Director mounted and cover on.
9. Canvas muzzle bags on tubes.

6104. Torpedoes-Fully ready condition.

1. Tubes trained out and secured in that position.
2. Current on firing circuit.
3. Impulse charges loaded, firing pin on "safe".
4. Firing keys inserted.

WHEN ACTION IS IMMINENT

1. Shift firing pin to firing position.
2. Men standing by tubes with mallets for percussion fire.

6105. .20-mm. gun-Ready condition.

1. Gun oiled and ready to fire mechanically, uncocked.
2. Gun cover on and not secured except in wet weather.
3. Magazine filled and in ready boxes. Extra magazines filled and on board.

6106. .20-mm. gun-Fully ready condition.

1. Gun cocked; should be uncocked for a few minutes every four hours when weather permits.
2. If weather is wet, cover over magazine and breech mechanism, not over muzzle.
 
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3. Safety on until ready to commence firing.
4. Magazine in place.
5. If weather permits gun manned continuously. If not gun secured pointing up.

6107. .50-caliber gun-Ready condition.

1. Guns clean and well oiled.
2. Oil buffers filled.
3. Head space set.
4. One thousand rounds up in each turret well cleaned and free from corrosion; not led up to gun.
5. Spare magazines loaded and at hand in tank room.
6. Waterproof cover on and secured only in wet weather. Normally off during daylight. Covers on, not secured at night.

6108. .50-caliber gun-Fully ready condition.

1. Lead belt up to gun, half load, put on safety.
2. If weather is wet, keep muzzle bags on guns, cover over turret.
3. Guns manned, trained on bow or probable target bearing.

6109. .45-caliber submachine gun-Ready condition.

1. Gun well oiled, cleaned and adjusted for firing.
2. Gun secured to port inside bulkhead of lower control station.
3. All magazines loaded and secured close to guns.
4. Magazines never to be installed until ready to open fire.

6110. .45-caliber submachine gun-Fully ready condition.

1. Removed from stowage and in hands of gunner.
2. Magazine at hand, ready to be loaded.
3. Gun cocked; safety on.

6111. Depth charges-Ready condition.

1. Pistols, extenders, detonators, and boosters installed.
2. Knobbed safety forks in place, not wired to rack.
3. Plain safety caps on.
4. Depth setting "safe".
5. White lines painted at 50 feet, 100 feet, 200 feet, 300 feet setting.
6. Depth charge howler operative.
7. Safety fork and toggle pin tripping gear in place.
 
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8. Knobbed safety cap with lanyard attached will be kept on each boat, ready for installation.

6112. Depth charges-Fully ready condition.

1. Replace plain safety caps with knobbed safety caps secured to racks. Do not wire safety forks to racks.
2. Depth settings are set as directed by boat captain after clearing port.

6113. F. S. generator-Ready condition.

1. Generator filled.
2. CO2 bottle charged.
3. Toggle pin in place on releasing handle, safety fork on toggle pin.
4. Releasing arm lashed with fish line to smoke tank ring.

6114. F. S. generator-Fully ready condition.

1. Same as "Ready".

CHAPTER 1. (B)

6115. .20-mm. gun data.

1. Rate of fire (not adjustable)-450 rounds/minute.

Muzzle velocity-2,725 feet/second.

2. Maximum depression, 5°. Maximum elevation, 87°.

3. Maximum range 5,500 yards at 36° elevation.

4. Time of flight:

500 yards 0.66 seconds.
1,000 yards 1.71 seconds.
1,300 yards 2.52 seconds.
1,500 yards 3.16 seconds.

5. At 35, 19-foot elevation (near maximum range).

Range 4,734 yards.
Maximum ordinate 3,840 feet 3,020 yards from gun.
Time of flight 31.74 seconds.

6. 50 percent zones.

Range Length Breadth Height Drift
Yards Yards Yard Feet Yards
500 30 1 1 1
1,000 30 1 1 2
1,500 30 1 1 4
 
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7. Superelevation.

Range Angle of superelevation
Angle of elevation of line of sight
0 30 45 60
Yards        
500 0°13' 0°11' 0° 9' 0° 6'
1,000 0°42' 0°36' 0°30' 0°21'
1,500 1°31' 1°19' 1° 4' 0°46'

It should be noted from the above that the Oerlikon characteristic makes for greater accuracy at high angles of fire.

8. Life of barrel.-The amount of life that a barrel will give, depends on how hot the barrel becomes during firing.

Five magazines, containing 60 rounds each, or a total of 300 rounds can be fired continuously without harm to the barrel.

Nine magazines, of 60 rounds each, or a total of 540 rounds, will cause serious wear if fired continuously.

If short pauses occur between the firing of each magazine, the wear will remain small, even after several thousand rounds.

During any prolonged firing, the barrel should be kept as cool as possible, either by frequent changes with the spare barrel, or by dousing the barrel with water.

6116. .50-caliber B. A. gun data (air cooled).

1. Rate of fire-500-650 rounds/minute-adjustable.
Muzzle velocity-(78 feet from muzzle).

Cartridges caliber-.50 M1-2,669 f/s.
Cartridges caliber-.50 M1,823-2,500 f/s.

Tracer is loaded to group with ball and A. P. at 1,000 yards.

2. Maximum range 7,125 yards at 642.3 mils elevation. Time of flight 39.7 seconds. Drift 6.7 mils.

 
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3. Time of flight.
500 yards 072 seconds.
1,000 yards 1.45 seconds.
1,500 yards 2.40 seconds.

4. Number of rounds first burst and subsequent bursts. An initial burst of 75 rounds may be fired, after which 20 rounds a minute may be fired. After waiting 15 minutes without firing, another 75 round burst may be fired. If an initial burst of only 25 rounds is fired, 25 rounds a minute may be fired continuously. The above rate of fire prevents overheating the gun, impairing its accuracy, and reducing its life. However, in combat the gun may and should be fired without regard to this.

 
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CHAPTER 2. MISCELLANEOUS DATA

A. Fuel Consumption and Cruising Radius

6201: One engine operation.

TABLE 1.-Fuel consumption and cruising radius, one engine, Admiral, (29/30) wheels

Chart showing gallons per hour vs. RPM with lines for cruising radius, knots, gal per hour.

 
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6202. Two engine operation.

TABLE 2.-Fuel consumption and cruising radius, two engines, Admiral, (29/30) wheels

Chart showing gallons per hour vs. RPM with lines for cruising radius, knots, gal per hour.

 
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6203. Three engine operation. TABLE 3.-Fuel consumption and cruising radius, three engines, Admiral, (29/30) wheels

Chart showing gallons per hour vs. RPM with lines for cruising radius, knots, gal per hour.

 
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6204. Composite table of all combinations.

TABLE 4.-Gasoline consumption with Admiral (29-30) wheels -77'

Elco boat

ONE-ENGINE OPERATION
R. p. m. Knots Gallons
per hour
Cruising
radius
700 8.3 17.5 1,420
800 9.5 22.5 1,270
900 10.3 28.8 1,070
1 1,000 11.1 31.7 1,050
1,100 11.8 39.2 903
TWO-ENGINE OPERATION
800 11.8 45.8 772
900 13.2 62. 5 633
1, 000 14. 7 70. 8 623
1, 100 17. 0 75. 8 672
1 1, 200 19. 3 80.8 718
1, 300 21. 5 87. 5 740
1, 400 23.5 100.8 704
1, 500 25. 1 120. 8 625
THREE-ENGINE OPERATION
700 10.4 46.6 669
800 12.8 72.5 531
900 15.2 81.7 558
1, 000 17.2 100.0 516
1, 100 19.4 107.5 542
1, 200 21.8 129.2 506
1, 300 25.0 140.0 536
1, 400 27.2 145.8 560
1, 500 28.4 162.5 524
1, 600 29.5 175.0 506
1, 700 32.4 183.3 530
1, 800 33.2 200.0 498
1, 900 34. 0 234.2 436
1 2,000 34.9 292.5 358
2, 100 37.2 314.2 355
2, 200 39.4 350.9 336
2, 300 40.2 426 6 282
2, 400 40.9 474.2 259

1 Maximum sustained speed.

Sea-Moderate.
Displacement 94,500.
Draft aft-5 feet 3 inches.
Draft forward-2 feet 5 inches.

 
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B. Submarine Data

6205. Rate of descent and lateral speed in crash dive.

TABLE 5.-Rate of descent and lateral speed in crash dive

Time (in seconds) submarine sighted and starts crash dive at 0 second Lateral distance (yards) traveled by submarine-measured from point where submarine started dive Depth setting (feet) Lead (yards) to obtain hit- measured from point where submarine started dive
0 0 50 30
1 30 105 50 135
40 140 100 185
50 175 100 220
60 210 150 271
70 245 150 306
80 280 200 357
90 315 200 392
100 350 250 443
110 385 250 478
120 420 250 513

1 Submarine periscope submerges.

The above is based on a rate of sinking of 300-pound depth charge of 6 foot/seconds for first 50 feet and 9 foot/seconds thereafter.

C. Radius of Visibility for Motor Torpedo Boats

6206.

TABLE 6.-Distance a vessel can be seen from a motor torpedo boat (height of eye 12 feet-horizon 4 miles-distance in nautical miles)

A vessel with a
masthead height of-
Can be seen
from a PT at-
Feet Miles
100 15. 5
80 14. 3
75 13.9
70 13. 6
65 13. 2
60 12.9
55 12.5
50 12. 1
45 11. 7
40 11. 2
35 10.8
30 10. 3
25 9. 7
20 9. 1
15 8.4
10 7.6
 
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