In the early 1900s, the Imperial Navy had developed a rather desperate need for a fast cruise capable of serving as a Destroyer Leader and fast scout. The Iaculum class was the result of this need. Fast, but poorly armed and armored, the class provided a needed service.
Four Ships:
--IRS Iaculum
--#2 (Sunk of the coast of Veracruz September 1914)
--#3
--#4
QuoteIaculum, Roman Imperial Republic Cruiser laid down 1905
Displacement:
3,000 t light; 3,097 t standard; 3,387 t normal; 3,619 t full load
Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(413.39 ft / 410.11 ft) x 42.65 ft x (13.94 / 14.65 ft)
(126.00 m / 125.00 m) x 13.00 m x (4.25 / 4.47 m)
Armament:
2 - 5.51" / 140 mm 50.0 cal guns - 85.98lbs / 39.00kg shells, 200 per gun
Breech loading guns in deck and hoist mounts, 1902 Model
2 x Single mounts on centreline ends, evenly spread
4 - 2.95" / 75.0 mm 50.0 cal guns - 13.23lbs / 6.00kg shells, 350 per gun
Quick firing guns in deck mounts, 1902 Model
4 x Single mounts on sides, evenly spread
Weight of broadside 225 lbs / 102 kg
Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.79" / 20 mm 0.39" / 10 mm 0.79" / 20 mm
2nd: 0.59" / 15 mm - -
- Protected deck - single deck:
For and Aft decks: 0.59" / 15 mm
Forecastle: 0.39" / 10 mm Quarter deck: 0.39" / 10 mm
Machinery:
Coal and oil fired boilers, steam turbines,
Direct drive, 2 shafts, 22,000 shp / 16,412 Kw = 26.08 kts
Range 3,500nm at 10.00 kts
Bunker at max displacement = 523 tons (90% coal)
Complement:
221 - 288
Cost:
£0.367 million / $1.467 million
Distribution of weights at normal displacement:
Armament: 64 tons, 1.9 %
- Guns: 64 tons, 1.9 %
Armour: 131 tons, 3.9 %
- Armament: 12 tons, 0.3 %
- Armour Deck: 119 tons, 3.5 %
Machinery: 1,715 tons, 50.6 %
Hull, fittings & equipment: 1,020 tons, 30.1 %
Fuel, ammunition & stores: 387 tons, 11.4 %
Miscellaneous weights: 70 tons, 2.1 %
- Hull below water: 5 tons
- Hull above water: 10 tons
- On freeboard deck: 50 tons
- Above deck: 5 tons
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,487 lbs / 675 Kg = 17.8 x 5.5 " / 140 mm shells or 0.5 torpedoes
Stability (Unstable if below 1.00): 1.50
Metacentric height 2.8 ft / 0.8 m
Roll period: 10.7 seconds
Steadiness - As gun platform (Average = 50 %): 71 %
- Recoil effect (Restricted arc if above 1.00): 0.11
Seaboat quality (Average = 1.00): 1.39
Hull form characteristics:
Hull has rise forward of midbreak,
a normal bow and a cruiser stern
Block coefficient (normal/deep): 0.486 / 0.494
Length to Beam Ratio: 9.62 : 1
'Natural speed' for length: 20.25 kts
Power going to wave formation at top speed: 54 %
Trim (Max stability = 0, Max steadiness = 100): 51
Bow angle (Positive = bow angles forward): 5.00 degrees
Stern overhang: 1.35 ft / 0.41 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 20.00 %, 22.15 ft / 6.75 m, 22.15 ft / 6.75 m
- Forward deck: 20.00 %, 22.15 ft / 6.75 m, 22.15 ft / 6.75 m
- Aft deck: 45.00 %, 9.84 ft / 3.00 m, 9.84 ft / 3.00 m
- Quarter deck: 15.00 %, 9.84 ft / 3.00 m, 9.84 ft / 3.00 m
- Average freeboard: 14.76 ft / 4.50 m
Ship tends to be wet forward
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 170.3 %
- Above water (accommodation/working, high = better): 135.2 %
Waterplane Area: 11,508 Square feet or 1,069 Square metres
Displacement factor (Displacement / loading): 84 %
Structure weight / hull surface area: 56 lbs/sq ft or 273 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.86
- Longitudinal: 1.31
- Overall: 0.90
Cramped 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
Misc Distribution
--Below Water (5t)
----5t Additional Pumps
--Above Water (10t)
----10t Short-Range Wireless
--On Deck (50t)
----12t 6x450mm Torpedos (45 Pattern B) [Three Single tube mounts per side]
----25t Long-Range Wireless
----13t Construction Reserve
--Above Deck (5t)
----5t Improved Aquisition Structures