April 1942:
If you lived in Galveston in 1941, you would have watched the Navy Yard finish fitting out the newest ship, BB-3 Invincible. Designed in 1937 and laid down in a US yard the following year, she and her sister were destined to replace the Austin Class, which had reached the end of their service life (though the war will change that in a later post).
Her parameters were impressive, and in clear violation of the London Treaty (which was falling apart by 1937 anyway):
Displacement:
32,830 t light; 35,038 t standard; 37,528 t normal; 39,521 t full load
Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(726.85 ft / 704.00 ft) x 104.00 ft x (26.00 / 27.17 ft)
(221.54 m / 214.58 m) x 31.70 m x (7.92 / 8.28 m)
Armament:
8 - 16.00" / 406 mm 45.0 cal guns - 2,065.47lbs / 936.88kg shells, 150 per gun
Breech loading guns in turret on barbette mounts, 1935 Model
4 x 2-gun mounts on centreline ends, evenly spread
2 raised mounts - superfiring
16 - 5.00" / 127 mm 38.0 cal guns - 59.33lbs / 26.91kg shells, 150 per gun
Dual purpose guns in deck and hoist mounts, 1934 Model
8 x 2-gun mounts on sides, evenly spread
4 raised mounts
16 - 1.06" / 27.0 mm 70.0 cal guns - 0.66lbs / 0.30kg shells, 150 per gun
Anti-air guns in deck mounts, 1935 Model
4 x 2 row twin mounts on side ends, evenly spread
4 raised mounts
Weight of broadside 17,484 lbs / 7,930 kg
Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 15.0" / 381 mm 457.60 ft / 139.48 m 12.24 ft / 3.73 m
Ends: Unarmoured
Main Belt covers 100 % of normal length
Main Belt inclined 15.00 degrees
- Torpedo Bulkhead - Additional damage containing bulkheads:
3.00" / 76 mm 457.60 ft / 139.48 m 25.22 ft / 7.69 m
Beam between torpedo bulkheads 80.00 ft / 24.38 m
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 15.0" / 381 mm 7.50" / 191 mm 15.0" / 381 mm
2nd: 2.00" / 51 mm 0.50" / 13 mm -
3rd: 0.50" / 13 mm - -
- Box over machinery & magazines:
6.00" / 152 mm
- Conning towers: Forward 15.00" / 381 mm
Machinery:
Oil fired boilers, steam turbines,
Electric motors, 4 shafts, 83,739 shp / 62,469 Kw = 26.00 kts
Range 10,000nm at 14.00 kts
Bunker at max displacement = 4,483 tons
Complement:
1,347 - 1,752
Cost:
£17.405 million / $69.620 million
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
63,240 lbs / 28,685 Kg = 30.9 x 16.0 " / 406 mm shells or 11.5 torpedoes
Stability (Unstable if below 1.00): 1.16
Metacentric height 7.0 ft / 2.1 m
Roll period: 16.5 seconds
Steadiness - As gun platform (Average = 50 %): 51 %
- Recoil effect (Restricted arc if above 1.00): 0.62
Seaboat quality (Average = 1.00): 1.03
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 78.9 %
- Above water (accommodation/working, high = better): 167.1 %
Waterplane Area: 59,700 Square feet or 5,546 Square metres
Displacement factor (Displacement / loading): 127 %
Structure weight / hull surface area: 251 lbs/sq ft or 1,228 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.23
- Longitudinal: 1.43
- Overall: 1.25
Excellent machinery, storage, compartmentation space
Excellent accommodation and workspace room
Designers faced quite a challenge building a modern battleship with only a 26' draft to ensure the vessel could depart in any tide from Galveston Harbor or the Port of Houston with sufficient clearance to calm the pilot's nerves. Like all Texas capital ships, she had turbo-electric drive. 15' inclined armor belts were designed to resist shells from potential European adversaries and additional emphasis was placed on protection against torpedos. Survivability was the guiding principle in their design - if lost during a war, they could not be replaced in a reasonable time like a light cruiser or destroyer. They also had the new 25mm/70 anti-aircraft machine guns fitted to protect the superstructures from air attack.
They were the first ships built with aircraft facilities on the stern and a hangar in the hull, similar to American cruiser designs of that time. She could carry as many as 6 aircraft (three in the hangar, one on the elevator, and one on each catapult) if necessary, though she typically supported 4.
They were also the first ships to deviate from the usual practice of basing the Marine contingent size on the overall size of the crew. A standard Marine Infantry Company was floated instead what would have been a larger landing force.
But in 1941 there were last-minute alterations to her final form. American assitance provided a CXAM air search radar, and additional fire control radars augmented the primary and secondary battery directors. These changes would radically alter the Navy's procedures for night action in the coming years.
BB-3 Invincible commissioned on 18 April 1942, and was painted in one of the early camouflage measures applied to capital ships:
BB-4 Independence commissioned the following month, and both were put to immediate work escorting convoys to Europe.