Post-WW1 Scouting Cruiser designed for a US fleet

**Derry, Heavy Cruiser laid down 1917**
Displacement:

8,350 t light; 8,672 t standard; 10,434 t normal; 11,844 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)

(620.50 ft / 609.00 ft) x 65.00 ft x (16.30 / 18.06 ft)

(189.13 m / 185.62 m) x 19.81 m x (4.97 / 5.50 m)

Armament:

5 - 7.00" / 178 mm 45.0 cal guns - 164.99lbs / 74.84kg shells, 220 per gun

Breech loading guns in deck mounts, 1900 Model

4 x Single mounts on centreline ends, evenly spread

2 raised mounts - superfiring

1 x Single mount on centreline, aft deck centre

1 double raised mount aft

4 - 3.00" / 76.2 mm 50.0 cal guns - 13.01lbs / 5.90kg shells, 450 per gun

Anti-air guns in deck mounts, 1915 Model

4 x Single mounts on sides, forward deck aft

Weight of broadside 877 lbs / 398 kg

Main Torpedoes

8 - 21.0" / 533 mm, 22.56 ft / 6.88 m torpedoes - 1.442 t each, 11.538 t total

In 2 sets of deck mounted side rotating tubes

Armour:

- Belts: Width (max) Length (avg) Height (avg)

Main: 3.50" / 89 mm 400.00 ft / 121.92 m 10.00 ft / 3.05 m

Ends: 1.00" / 25 mm 70.00 ft / 21.34 m 10.00 ft / 3.05 m

139.00 ft / 42.37 m Unarmoured ends

Main Belt covers 101 % of normal length

- Armoured deck - single deck:

Fore and Aft decks: 1.50" / 38 mm

Forecastle: 0.25" / 6 mm Quarter deck: 0.50" / 13 mm

- Conning towers: Forward 4.00" / 102 mm, Aft 0.00" / 0 mm

Machinery:

Oil fired boilers, steam turbines,

Geared drive, 2 shafts, 79,286 shp / 59,147 Kw = 31.00 kts

Range 12,500nm at 14.00 kts

Bunker at max displacement = 3,172 tons

Complement:

516 - 671

Cost:

£1.351 million / $5.404 million

Distribution of weights at normal displacement:

Armament: 162 tons, 1.6 %

- Guns: 139 tons, 1.3 %

- Weapons: 23 tons, 0.2 %

Armour: 1,321 tons, 12.7 %

- Belts: 604 tons, 5.8 %

- Armour Deck: 676 tons, 6.5 %

- Conning Tower: 41 tons, 0.4 %

Machinery: 2,906 tons, 27.9 %

Hull, fittings & equipment: 3,830 tons, 36.7 %

Fuel, ammunition & stores: 2,085 tons, 20.0 %

Miscellaneous weights: 130 tons, 1.2 %

- Hull below water: 40 tons

- Hull above water: 20 tons

- On freeboard deck: 30 tons

- Above deck: 40 tons

Overall survivability and seakeeping ability:

Survivability (Non-critical penetrating hits needed to sink ship):

16,961 lbs / 7,693 Kg = 98.9 x 7.0 " / 178 mm shells or 1.7 torpedoes

Stability (Unstable if below 1.00): 1.32

Metacentric height 4.3 ft / 1.3 m

Roll period: 13.1 seconds

Steadiness - As gun platform (Average = 50 %): 80 %

- Recoil effect (Restricted arc if above 1.00): 0.12

Seaboat quality (Average = 1.00): 1.37

Hull form characteristics:

Hull has a flush deck,

a straight bulbous bow and a cruiser stern

Block coefficient (normal/deep): 0.566 / 0.580

Length to Beam Ratio: 9.37 : 1

'Natural speed' for length: 24.68 kts

Power going to wave formation at top speed: 55 %

Trim (Max stability = 0, Max steadiness = 100): 58

Bow angle (Positive = bow angles forward): 15.00 degrees

Stern overhang: 4.00 ft / 1.22 m

Freeboard (% = length of deck as a percentage of waterline length):

Fore end, Aft end

- Forecastle: 20.00 %, 28.00 ft / 8.53 m, 25.00 ft / 7.62 m

- Forward deck: 40.00 %, 25.00 ft / 7.62 m, 22.00 ft / 6.71 m

- Aft deck: 25.00 %, 22.00 ft / 6.71 m, 20.00 ft / 6.10 m

- Quarter deck: 15.00 %, 20.00 ft / 6.10 m, 21.00 ft / 6.40 m

- Average freeboard: 22.97 ft / 7.00 m

Ship space, strength and comments:

Space - Hull below water (magazines/engines, low = better): 96.2 %

- Above water (accommodation/working, high = better): 228.7 %

Waterplane Area: 28,044 Square feet or 2,605 Square metres

Displacement factor (Displacement / loading): 136 %

Structure weight / hull surface area: 90 lbs/sq ft or 442 Kg/sq metre

Hull strength (Relative):

- Cross-sectional: 0.96

- Longitudinal: 1.41

- Overall: 1.00

Adequate machinery, storage, compartmentation space

Excellent accommodation and workspace room

Ship has slow, easy roll, a good, steady gun platform

Good seaboat, rides out heavy weather easily