1948: The Texas Navy launches its first warship following the end of World War 2.
The San Marcos Class heavy cruisers replace the Rio Grande Class. Though the Rio Grandes are just shy of twenty years in service, they have been eclipsed by wartime advances in technology and do not have any more room for growth. Rio Grande is laid up in reserve in 1948, and the Sabine follows in 1949.
The San Marcos Class was perhaps the greatest challenge to Naval design and construction for the Texas Navy. Normally, large capital ships are built under contract in the US, where slipways are large enough for hulls over 600 feet in length. The largest Texas slipways belonged to Gray’s Iron Works, and the two available during the war were reserved for building the San Antonio Class light cruisers. US yards were at capacity during the war, and there were no yards available to the Texas Navy for building a heavy cruiser to replace the Rio Grandes.
In 1944, the third of the San Antonios was nearing completion, and its slipway would be available soon after launch. The Navy, desperate for a modern heavy cruiser, challenged the Design Bureau to find a way to get a heavy cruiser into a light cruiser hull. The inherent design limitation was a length of no more than 600 feet.
The plans drawn up by the Design Bureau were impressive. The San Marcos would be armed with 8”/55 rapid fire guns, new 5”/54 dual purpose secondaries, and the required mass of 40mm Bofors and 25mm heavy machine guns for operations in the Pacific. Required range was the standard 10,000 miles at cruising speed, with a maximum speed of 30 knots. Air complement would be the standard flight of 4 observer floatplanes.
Needless to say there were skeptics that it could be done at all, but it was. The San Marcos was laid down in 1945, but was incomplete when the war ended in August. She and her sister the San Saba survived the postwar cuts in naval construction. San Marcos took to the water and commissioned in 1948.
1945 Heavy Cruiser Plan 8, Republic of Texas Heavy Cruiser laid down 1945
Displacement:
13,712 t light; 14,289 t standard; 15,948 t normal; 17,275 t full load
Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(599.37 ft / 582.00 ft) x 75.00 ft x (23.25 / 24.71 ft)
(182.69 m / 177.39 m) x 22.86 m x (7.09 / 7.53 m)
Armament:
8 - 8.00" / 203 mm 55.0 cal guns - 276.33lbs / 125.34kg shells, 150 per gun
Breech loading guns in turret on barbette mounts, 1945 Model
4 x 2-gun mounts on centreline ends, evenly spread
2 raised mounts - superfiring
12 - 5.00" / 127 mm 38.0 cal guns - 59.33lbs / 26.91kg shells, 150 per gun
Dual purpose guns in deck and hoist mounts, 1945 Model
4 x 2-gun mounts on sides, evenly spread
2 x 2-gun mounts on centreline ends, evenly spread
2 double raised mounts
12 - 3.00" / 76.2 mm 50.0 cal guns - 14.29lbs / 6.48kg shells, 150 per gun
Anti-air guns in deck mounts, 1945 Model
6 x 2-gun mounts on sides, evenly spread
4 raised mounts
Weight of broadside 3,094 lbs / 1,403 kg
Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 8.00" / 203 mm 378.30 ft / 115.31 m 17.00 ft / 5.18 m
Ends: 6.00" / 152 mm 203.68 ft / 62.08 m 8.50 ft / 2.59 m
Main Belt covers 100 % of normal length
Main Belt inclined -15.00 degrees (positive = in)
- Torpedo Bulkhead - Strengthened structural bulkheads:
3.00" / 76 mm 378.30 ft / 115.31 m 12.50 ft / 3.81 m
Beam between torpedo bulkheads 65.00 ft / 19.81 m
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 8.00" / 203 mm 8.00" / 203 mm 8.00" / 203 mm
2nd: 5.00" / 127 mm 1.00" / 25 mm 5.00" / 127 mm
3rd: 0.50" / 13 mm - -
- Box over machinery & magazines:
4.00" / 102 mm
Forecastle: 2.00" / 51 mm Quarter deck: 2.00" / 51 mm
- Conning towers: Forward 8.00" / 203 mm, Aft 0.00" / 0 mm
Machinery:
Oil fired boilers, steam turbines,
Electric motors, 4 shafts, 79,093 shp / 59,003 Kw = 30.00 kts
Range 10,000nm at 15.00 kts
Bunker at max displacement = 2,986 tons
Complement:
709 - 922
Cost:
£7.460 million / $29.841 million
Distribution of weights at normal displacement:
Armament: 967 tons, 6.1 %
- Guns: 967 tons, 6.1 %
Armour: 4,705 tons, 29.5 %
- Belts: 2,571 tons, 16.1 %
- Torpedo bulkhead: 525 tons, 3.3 %
- Armament: 1,146 tons, 7.2 %
- Armour Deck: 353 tons, 2.2 %
- Conning Tower: 109 tons, 0.7 %
Machinery: 1,997 tons, 12.5 %
Hull, fittings & equipment: 6,043 tons, 37.9 %
Fuel, ammunition & stores: 2,236 tons, 14.0 %
Miscellaneous weights: 0 tons, 0.0 %
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
32,728 lbs / 14,845 Kg = 127.8 x 8.0 " / 203 mm shells or 5.6 torpedoes
Stability (Unstable if below 1.00): 1.09
Metacentric height 3.8 ft / 1.2 m
Roll period: 16.1 seconds
Steadiness - As gun platform (Average = 50 %): 56 %
- Recoil effect (Restricted arc if above 1.00): 0.48
Seaboat quality (Average = 1.00): 1.12
Hull form characteristics:
Hull has a flush deck,
a straight bulbous bow and large transom stern
Block coefficient (normal/deep): 0.550 / 0.560
Length to Beam Ratio: 7.76 : 1
'Natural speed' for length: 27.94 kts
Power going to wave formation at top speed: 58 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 20.00 degrees
Stern overhang: 6.00 ft / 1.83 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 20.00 %, 31.25 ft / 9.53 m, 26.25 ft / 8.00 m
- Forward deck: 30.00 %, 26.25 ft / 8.00 m, 23.25 ft / 7.09 m
- Aft deck: 35.00 %, 23.25 ft / 7.09 m, 23.25 ft / 7.09 m
- Quarter deck: 15.00 %, 23.25 ft / 7.09 m, 24.25 ft / 7.39 m
- Average freeboard: 24.78 ft / 7.55 m
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 69.3 %
- Above water (accommodation/working, high = better): 204.0 %
Waterplane Area: 31,715 Square feet or 2,946 Square metres
Displacement factor (Displacement / loading): 136 %
Structure weight / hull surface area: 149 lbs/sq ft or 727 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.09
- Longitudinal: 2.09
- Overall: 1.16
Excellent machinery, storage, compartmentation space
Excellent accommodation and workspace room
Her most impressive feature was the compact and efficient turbo-electric powerplant. It consumed far less volume than earlier plants, allowing a larger number of critical spaces under the protection of the ship's armor. The 40mm Bofors were replaced mid-construction with new 3"/50 anti-aircraft guns from the United States. The 25mm guns were eliminated altogether to reduce total expense. And she was all business - superstructure spaces dedicated to combat operations were kept to a minimum, the rest going to routine requirements and accomodations. The majority of combat spaces were under armor. Crew spaces were comfortable, but not lavish.