U.S. Submarine
Deck Guns, a short description:
The Beginnings
The submarine in its present use,
submerged and stealthy, requires the automobile torpedo, which itself travels submerged
and undetectable. In addition, the boats today are equipped with missiles that
pack a great punch and can reach out to ranges of upwards of 1500 miles. Thus is is difficult to comprehend the use
of a deck gun. To realize the usefulness
of such a weapon, one must look at the context of the warfare in which it was
used. Submarines, up to 1917, had as their targets, ships which ranged in size
from battleships to small fishing trawlers.
Most, if not all of these targets, were ill-equipped or not equipped for
opposing a submerged submarine.
The original use of the
The European considerations in
submarine design was somewhat different.
There, the submarine, even with its limited seagoing range, was an
offensive weapons system, operating in the Baltic, North Sea and along the
coasts of
In 1913, with the construction of
the U-19 type, the German Navy equipped its submarines with an artillery piece
topside to be used when the ship was surfaced.
The Royal Navy first equipped the HMS D-4 with a rretractable 12 pounder
gun around the same time. These deck
guns could engage an unarmed ship and sink it without expending a torpedo. In the early days of World War I, the
submarine operated within the ruled dictated for surface warships. If it engaged an enemy warship, it could fire
without warning. However when the target
was a civilian passenger ship or freighter the boat was reqired to stop and
inspect the cargo of non-warships and if the ship belonged to a belligerent
and/or was carrying war material to a belligerent, it could be sunk or taken as
prize after its crew had been released to the lifeboats. Generally, the limited
size of the submarine crew precluded the taking of the ship as a prize and
sailing it to a friendly or neutral port.
There was no need to expend a torpedo against a small freighter if time
permitted other forms of sinking. Torpedos were expensive and if other means of
sinking the boarded ship were available, they were preferable. Explosive charges were carried on board some
submarines for scuttling the boarded ship. The other option was to use the deck
gun. As the rules of submarine
engagement changed to unrestricted sinking of enemy ships, the deck gun was
still useful for engaging unarmed or lightly armed small shipping. It also gave the submarine a sting against
aircraft who might catch the boat on the surface.
The deck gun (untill late 1945) had
no fire control system other than that with which the gun was equipped. It was strictly a point and shoot operation
with the range to the target being estimated by seaman’s eye and the azmuth
being estimated by the pointer’s practice.
The submarine was by no means a stable platform so firing “on the roll”
was a practiced skill. This skill was,
however, common, as very few if any similar guns on ships had gyro stable fire
control systems at the time. This
rudementary fire control method was compensated for by the fact that most often
the target was at close, almost boresighted, range. And, very seldom was a ship taken under fire
in bad weather.
It was up to the commanding officer
to decide which targets warranted a torpedo and which would be engaged with the
deck gun. Because the deck gun had to be
used on the surface, its use put the submarine in a vulnerable position. The gun was not sufficiently large to enable
the sub to equal the lethality of a warship and as the enemy armed more and
more of the small freighters and merchantmen which were the prey of boats using
deck guns, the risk to the submarine became greater.
. The earliest gun to be used by the
US Submarine Force was the dimunitive 3” Mark IX. First installed on the L-boats destined for
service in European waters, this was a retractable, sliding breechblock
quickfiring gun with a maximum range of about 8000 yards. The
As a word of explanation, a standard
way to refer to a gun type is by its bore diameter and bore length. Further refinement of the gun type is by the
Mark and Modification number. The bore
diameter is normally given in inches and the bore length is given in
calibers. A caliber is one bore
diameter. Thus for a 3” gun, the bore
diameter, measured land to land is 3”.
The length of the bore is 23 calibers which is 23 times 3” or 69
inches. A 5”/51 has a bore diameter of 5
inches and a bore length of 255 inches.
A 16”/50 has a bore diameter of 16” and a bore length of just over 66
feet 8 inches. Each major type also was
given a Mark number by the Bureau of Ordnance (BuOrd). A gun could have the same bore size and
length and be a different Mark. When
discussing the entire range of 5” guns in the Navy, it is useful to use the
Mark number. For submarine guns only, is
is normally not necessary. Modifications
to a particular Mark were also numbered. Thus, a gun was fully described with its bore
diameter, bore length, Mark and Mod nubmers.
The 3” gun in this first section is the 3”/23 Mark IX, Mod 0. The 3”/23 was a small short barreled deck gun
which had the unique capability to be retracted into the deck superstructure so
only the barrel and part of the recoil cylinder showed above the deck. This small gun was seen to be inadequate
against even small antisubmarine craft of WWI.
In addition to the use against
surface targets, WWI showed that aircraft were a very real threat to submarines
thus some thought was being given to a deck gun for anti aircraft use given
that the submarine might not be able to dive to escape. Early on it was felt that equipping the submarines
with small caliber machine guns would suffice.
However, the 3”/50 caliber dual purpose gun was being manufactured for
use by small surface craft so it was adapted for submarine use. Submarine commanders felt the 3” caliber was
too small and lobbied for larger guns.
Some wanted the 4” caliber and other wished for 5” and larger. The S-Class had 4”/50 deck guns and 3”/50
deck guns installed as they became available.
Guns For a New War
The Submarine force was in a state of design
flux following WWI. Several groups who
carefully studied the strategy and tactics of submairne warfare lobbied for
their interests. Captain Thomas C. Hart
was president of the General Board that was responsible for setting forth
design specifications for shipbuilding was not in favor of arming submarines with
large deck guns. He felt that the
submarine was a weapon that supported the battle fleet and could defend the
coast of the
The 6”/53 Mark 17 Mod 1
There were three notable exceptions
to this design compromise. They were the
three large ‘cruiser’ submarines the USS Argonaut (originally designed and
built as a mine layer), the USS Nautilus and USS Narwhal. These three had two large 6”/50 gun mounted
one forward of the conning tower and one aft.
The 6”/53 Mark 17 Mod 1 was the
largest deck gun carried by a
Designation 6"/53 (15.2 cm)
Gun Weight 10.11
tons (10.27 mt)
Gun Length oa 325.0 in
(8.255 m)
Bore Length 318.0 in
(8.077 m)
Rifling Length 265.3
in (6.713 m)
Twist Uniform
RH 1 in 35
Chamber Volume 2,100 in3
(34.4 dm3)
Rate Of Fire 6 - 7
rounds per minute
.
Ammunition
Type Bag
Projectile
Types and Weights Common
Mark 24 - 105 lbs. (47.6 kg)
Bursting
Charge Common
- 5.75 lbs. (2.6 kg)
Projectile
Length Common
- 27 in (68.6 cm)
Propellant Charge 44
lbs. (20 kg)
Muzzle
Velocity AP
- 3,000 fps (914 mps)
HC - 2,400 fps (732 mps)
.
Range
.Armor
Penetration with 105 lbs. (47.6 kg) Common Shell used on Submarines
.
Range Side Armor Deck Armor
8,200 yards (7,500 m) 4.0" (102 mm) ---
12,200 yards (11,160 m) 3.0" (76 mm) ---
17,000 yards (15,540 m) 2.0" (51 mm) ---
19,400 yards (17,740 m) --- 1.0"
(25 mm)
22,600 yards (20,670 m) --- 1.5"
(38 mm)
Note:
These figures are taken from armor penetration curves published in 1942.
.
Wet Mount
Submarines (2): Mark 15
Weight
37,700 lbs. (17,100 kg)
Elevation Submarine
Mount: -10 / +25 degrees
The 3”/50 Mk 11 Mods
4,5,6,and 7
The 3”/50 Mk 11 Mods 4,5,6,and 7 was
the most common weapon mounted on submarines at the beginning of World War
II. This could fire a 13 pound
projectile to a maximum range of just over 14,000 yards. The 3”/50 deck gun
came in two varieties, the single purpose and the dual purpose. The main difference that one can see in
photographs is that the dual purpose, being also an antiaircraft gun, has a
higher mounting. [The trunions are mounted further above the base ring] so it
has a higher possible elevation. These
were first mounted aft of the conning tower fairwater which provided a wider
dryer gun working area and the initial tactical thinking was that the deck gun
would be used as a defensive rather than an offensive weapon. The 3”/50 was a standard type weapon and was
carried on destroyers and cruisers generally for anti aircraft protection. The
3”/50 was a good dual purpose gun which could be fired rapidly and due to its
short barrel length and light weight could be trained and elevated
quickly.
Most
boats were equipped with the deck gun on a mount abaft the conning tower
fairwater. However, wartime experience showed that a deck gun on the forward
deck might be better. The request for approval was made to BuOrd and
BuShips. There were three main reasons
for moving the deck gun forward of the conning tower fairwater. The access to the gun could be through the
conning tower hatch rather than using the conning tower watertight door which,
viewed as a weak spot in the submarine design, was being removed as conning
towers were overhauled. The forward
mount added little to the silhouette and gave a greater control over the gun’s
operation. Finally, the gun crew was
less likely to go overboard running aft to an aft mounting. Approval for the forward mounting was given
in early 1942, but was subject to the CO’s approval.
Gun
Gun Weight 1,760 lbs. (798 kg)
Gun
Length oa 159.7 in (4.055
m)
Bore
Length 150.3 in
(3.816 m)
Rifling
Length 126.1 in (3.204
m)
Grooves (24) 0.03 in deep
(0.76 mm)
Twist Mark 10:
Increasing RH 0 to 1 in 25
Chamber
Volume 217 in3
(3.56 dm3)
Rate
Of Fire 15 - 20 rounds
per minute
.
Ammunition
.
Type Fixed
Weight
of Complete Round 24
lbs. (10.9 kg)
Projectile Types
and Weights HC - 13
lbs. (5.9 kg)
AP Mark 29 - 12.85 lbs. (5.8 kg)
Bursting
Charge HC
- 1.27 lbs. (0.58 kg)
Propellant
Charge 3.7
lbs. (1.68 kg)
Cartridge (empty) - 9 lbs. (4.1 kg)
Muzzle
Velocity 2,700
fps (823 mps)
.
Range
.
Elevation With 13 lbs. (5.9 kg) HE
MV = 2,700 fps (823 mps) Striking Velocity Angle
of Fall
2.0 degrees 3,000 yards (2,740 m) 1,230
fps (375 mps) 3.4
4.3 degrees 4,500 yards (4,150 m) 971
fps (296 mps) 8.4
43 degrees 14,600 yards (13,350 m) --- ---
AA Ceiling 30,400 feet (9,270 m) --- ---
Note: Time
of flight for MV = 2,700 fps (823 mps)
3,000 yards (2,740 m): 5.1 seconds
4,500 yards (4,150 m): 9.3 seconds
.
Weight 3.0 to 4.2 tons
(3.1 to 4.3 mt)
Elevation -15 / +85 degrees
Elevation
Rate Manually operated,
only
Train 360 degrees
Train
Rate Manually
operated, only
Gun
recoil N/A
.
The 4”/50 Mark 12
The 4” gun came in two types, the 4”50 Mark 12
Mod 6 and the 4”/50 Mark 12 Mod 44. The
main difference was the method of maintaining the bore watertight. These could fire a 33 pound projectile to a
max range of over 16,000 yards. These
guns were installed on S-class boats forward of the fairwater. The superstructure was widened to provide a
working surface for the gun crew. The
gun was not installed on the after deck due to the lack of under deck space for
the gun foundation. When these boats were retired from active patrolling and
assigned to a training role the 4”/50 was replaced by a 3”/50 and the larger
weapon sent to be installed on fleet submarines in the Pacific. The gun was initally to be standard equpment
on The V-7 design and later but was vetoed by SecNav who insisted on the boats
being equipped with the 3”/50. Also, the
4”/50 was too heavy for some of the older fleet boats due to weight margin
restrictions.
Gun Characteristics
Gun
Weight 2.725 tons (2.769 mt)
Gun
Length oa 206.5 in (5.2496 m)
Bore
Length 200.0 in (5.080 m)
Rifling
Length 165.0 in (4.190 m)
Twist Most Marks and Mods:
Increasing RH 0 to 1 in 31.17
Chamber Volume 654.5 in3
(10.73 dm3)
Rate
Of Fire 8 - 9 rounds per minute
.
Ammunition
.
Type Fixed
Weight
of Complete Round 62.4 -
64.75 lbs. (28.3 - 29.4 kg)
Projectile
Types and Weights AP - 33
lbs. (14.97 kg)
HC - N/A
Bursting
Charge N/A
Projectile
Length N/A
Propellant
Charge 14.5
lbs. (6.58 kg)
Cartridge - 31 lbs. (14 kg)
Muzzle
Velocity 2,900
fps (884 mps)
Working
Pressure 17
tons/in2 (2,680 kg/cm2)
Range
20 degrees 15,920 yards (14,560 m)
Single Mounting
Modified Mark 12
Weight Mark 12: 4.53 - 5.63 tons
(4.60 - 5.71 mt)
Elevation -15 / +20 degrees
Elevation
Rate Manual operation, only
Train about +150 / -150
degrees
Train
Rate Manual operation,
only
The
5”/51
The
5”/51 was adapted from the battleship 5” open mount and carried the Mark 13 Mod
11 designation). These were first
installed on the V-1,2,3 (Bass, Barracuda and Bonita) but were removed and
replaced by the 3”/50 in a weight reduction program as the three V boats were
overweight by 30 to 40 tons. In July
1942, Admiral Lockwood, who was Commander Submarines Southwest Pacific, got
permission from BuOrd to have the 5”/51 deck guns that were being removed from
from the V-boats (Bass, Barracuda and Bonita) shipped to him. He had these installed on the USS Tambor
(SS-198), USS Tautog (SS-199), USS Thresher (SS-200), USS Gar (SS-209), USS
Tuna (SS-203), and the USS Grayling (SS-206) while these boats were in overhaul
in Fremantle. These guns had a higher penetration power than the 5”/25
battleship gun. The gun was harder to
handle than the 5”/25 because of its length and weight and had a slower rate of
fire. In addition, its projectile and
propellant charge were separate as a function of its being derived from a
‘bagged charge’ weapon. Initially placed
on the V-1, 2 and 3 forward of the conning tower fairing, however it was felt
that this position would be used during peacetime with the other position on
the after deck being used also during wartime, thus making the boat similar to
the German ‘cruiser submarine’ design.
Gun Characteristics
.
Designation 5"/51 (12.7 cm)
Gun
Weight 5.05 tons (5.13 mt)
Gun
Length oa 261.25 in (6.636 m)
Bore
Length 255 in (6.477 m)
Rifling
Length 212.1 in (5.387 m)
Chamber Volume 1,202 in3
(19.7 dm3)
Rate
Of Fire 8 - 9 rounds per minute
Ammunition
.
Type Bag
Projectile
Types and Weights Common Mark
15 - 50 lbs. (22.7 kg)
Bursting
Charge Common
- 1.73 lbs. (0.78 kg)
Propellant
Charge 24.5
lbs. (11.1 kg)
Muzzle
Velocity Common
- 3,150 fps (960 mps)
Range
.
Elevation
Range
@ 15 degrees 14,050
yards (12,850 m)
"Wet"
Single Mountings
Submarines: Barracuda (1), Bonita (1) and "T" (1): Mark
18
Weight P mountings: 10.0 to 11.9 tons
(10.2 to 12.1 mt)
Mark
18: 10.7 tons (10.9 mt)
Mark
18: -8.5 / +25 degrees
Elevation
Rate Manual operation, only
Train about +150 / -150 degrees
Train
Rate Manual operation, only
The
5”/51 Mark 13
The
gun that became the standard during the latter stages of WWII and replaced the 3” and 4” guns as boats
went thorough mid war overhauls was the 5”/25 Mark 40 Mod 0. It was first installed as new construction in
USS Spadefish in 1944. This gun could
fire a 53 pound projectile to a range of over 14,000 yards. The weapon was standard on older battleship
as a secondary battery. To modify it for submarine use, the mount was
rebuilt to have a lower trunnion height (thus removing the gun from an
antiaircraft role) and a protective steel plate was built over the aiming
sights. The breech block and rifled
barrel liner had already been changed to stainless steel to make the gun less
suceptable to salt corrosion thus making the gun a “wet” design. This design was ready for installation in
August 1944.
Gun Weight Barrel Weight (all except Mark 17):
2,105 lbs. (955 kg)
Barrel Weight (Mark 17): 2,163 lbs. (981 kg)
Weight
with housing: about 4,270 lbs. (1,937 kg)
Gun
Length oa 142.25 in (3.613 m)
Bore
Length 125 in (3.175 m)
Rifling
Length 98.1 in (2.492 m)
Grooves (45) 0.05 in deep (1.27 mm)
Lands N/A
Twist Uniform RH 1 in 25
Chamber
Volume 431 in3 (7.06 dm3)
Rate
Of Fire 15 - 20 rounds per minute
.
Ammunition
.
Type All
except the Mark 17: Fixed
Weight of Complete Round about
80 lbs. (36.3 kg)
Projectile
Types and Weights HC
- 53.85 lbs. (24.43 kg)
Bursting
Charge HE
- 5.63 lbs. (2.55 kg)
Propellant
Charge 9.6
lbs. (4.35 kg)
Muzzle
Velocity 2,200
fps (808 mps)
Working
Pressure 16.7
tons/in2 (2,630 kg/cm2)
Range
@ 40 degrees 14,200
yards (12,980 m)
The Mark 40
submarine mount had a maximum elevation of 40 degrees.
Weight Mark
40: 12,600 to 14,000 lbs. (5,715 to 6,350 kg)
Elevation Mark
40: -10 / +40 degrees
Late
in WWII there were sufficient 5”/25 Mk 40’s available to mount two on the
boats. The first to be so fitted was USS
Sennet (SS-408) quickly followed by
Haddock and Lagarto. In September 1945
BuOrd approved the dual installation for all fleet submarines.
Seven boats were fitted with two 5”/25s and a
fire control system with gyro stabalization.
Only one, the USS Sea Cat was ready before war’s end. The others were the USS Manta, USS Entemedor,
USS Sea Dog, USS Sea Poacher, USS Sea Robin and USS Sennet.
Early
in WWII it was seen that the range of the .50 caliber and .30 caliber machine
guns in the antiaircraft role was too short to be effective. Therefore the Bofors designed 40 mm
antiaircraft gun and the 20 mm Oerlikon type were selected to be standard
equipment. Older EB design S-boats (S-42 to S-47) were equipped with the
20mm The 40mm was the Single Mount Base
Ring type Mark 3 Mod 0. The 20 mm came
in two varieties the single mount open or shielded pedestal type Mark 10 Mod 0
and the twin mount open or shielded pedestal type Mark 24 Mod 5. These guns would be mounted on platforms
forward and aft of the bridge (fore and aft of the conning tower fairwater) or
in the case of the 20mm occasionally on the main deck.
.
Designation
British:
20 mm/70 (0.79") Mark II
Ship
Class Used On Almost all
Allied ships during World War II
Date
Of Design about
1939
Date
In Service
Gun
Weight 150
lbs. (68.04 kg)
Gun
Length oa 87 in
(2.210 m)
Bore
Length 55.1 in
(1.400 m)
Rifling
Length 49.1 in
(1.246 m)
Grooves (9) 0.015 in
deep x 0.205 (0.38 x 5.207 mm)
Twist Uniform
RH 1 in 36
Chamber
Volume 2.127 in3
(34.855 cm3)
Rate
Of Fire Cyclic:
450 rounds per minute
Practical: Between 250 to 320 rounds per minute
Ammunition
.
Type Fixed
Projectile Types
and Weights USA
HE Mark 3 - 0.271 lbs. (0.123 kg)
HE-I Mark 3 - 0.271 lbs. (0.123 kg)
HE-T Mark 4 - 0.262 lbs. (0.117 kg)
HE-T Mark 7 - 0.271 lbs. (0.123 kg)
AP-T Mark 9 - 0.269 lbs. (0.122 kg)
Weight
of Complete Round 8.5 oz
(0.241 kg)
Bursting Charge USA
HE Mark 3 - 0.024 lbs. (0.011 kg)
HE-I Mark 3 - 0.017 lbs. (0.008 kg)
HE-T Mark 4 - 0.010 lbs. (0.005 kg)
HE-T Mark 7 - 0.010 lbs. (0.005 kg)
AP-T Mark 9 - None
Projectile
Length N/A
Complete round up to 7.18 in (18.2 cm) long
Propellant
Charge
Brass Cartridge: 0.2 lbs. (0.09 kg)
Cartridge 20
mm x 110RB
Muzzle
Velocity New
Gun: 2,770 fps (844 mps)
Average Gun: 2,725 fps (835 mps)
Working
Pressure
Approximate
Barrel Life 9,000
rounds
Range @ 10
degrees 3,450 yards (3,154 m)
Range
@ 15 degrees 3,950 yards
(3,612 m)
Range
@ 20 degrees 4,275 yards
(3,909 m)
Range
@ 25 degrees 4,525 yards
(4,138 m)
Range
@ 30 degrees 4,650 yards
(4,252 m)
Range
@ 35 degrees 4,725 yards
(4,320 m)
Range
@ 40 degrees 4,775 yards
(4,366 m)
Range
@ 45 degrees 4,800 yards
(4,389 m)
AA
Ceiling 10,000
feet (3,048 m)
.
Designation
40
mm/56 (1.57") Mark 1, Mark 2 and M1
Weight
about 1,150 lbs. (522 kg) [water-cooled]
Gun
Length oa 148.8 in (3.780 m)
Bore
Length 88.6 in (2.250 m)
Rifling
Length 75.85 in (1.927 m)
Grooves (16) 0.0236 in deep x 0.220 (0.60 x 5.59 mm)
Lands
0.0892 in (2.66 mm)
Twist
Increasing RH 1 in 45 to 1 in 30
Chamber
Volume 28.3 in3 (0.464 dm3)
Rate
Of Fire 120 rounds per minute
Only
once did a submarine skipper take on in a gun fight an enemy that proved to be
lethal, that was the USS S-44 which, thinking it was shooting at a freighter,
found it was, in fact, a Japanese destroyer.
The S-44 was sunk in that action on 7 October 1943.
Sources:
The website:
http://www.navweaps.com/; Owned and Operated by
Tony DiGiulian
"Naval
Weapons of World War Two" by John Campbell
"US Cruisers: An Illustrated Design History," "US
Submarines through 1945: An Illustrated Design History";
Destroyers: An Illustrated Design History" and "US Naval
Weapons" all by Dr. Norman Friedman;
"Range and
Ballistic Tables 1935" by
“The Fleet Submarine in the