Aztec Ships and Refits, 1914-1915

[TacCovert4]

First.....a planned rebuild of the 500t Scimitar-class DD.  Because in it's current form it is hilariously out of date with a 700nm range and relatively slow compared to cruisers and destroyers already coming into service worldwide.  In its current form it is barely competitive as an inshore patrol boat.  Plus it's 10 years old, time for a refit anyway.....

Scimitar, Aztec Destroyer laid down 1904 (Engine 1914)

Displacement:
   499 t light; 514 t standard; 568 t normal; 612 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (265.94 ft / 262.47 ft) x 26.25 ft x (7.22 / 7.58 ft)
   (81.06 m / 80.00 m) x 8.00 m  x (2.20 / 2.31 m)

Armament:
      3 - 2.76" / 70.0 mm 45.0 cal guns - 10.56lbs / 4.79kg shells, 200 per gun
     Quick firing guns in deck mounts, 1904 Model
     3 x Single mounts on centreline, evenly spread
      Weight of broadside 32 lbs / 14 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   1.00" / 25 mm         -               -

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 15,120 shp / 11,279 Kw = 30.00 kts
   Range 1,620nm at 15.00 kts
   Bunker at max displacement = 98 tons

Complement:
   57 - 75

Cost:
   £0.061 million / $0.245 million

Distribution of weights at normal displacement:
   Armament: 6 tons, 1.1 %
      - Guns: 6 tons, 1.1 %
   Armour: 7 tons, 1.1 %
      - Armament: 7 tons, 1.1 %
   Machinery: 302 tons, 53.1 %
   Hull, fittings & equipment: 172 tons, 30.2 %
   Fuel, ammunition & stores: 69 tons, 12.2 %
   Miscellaneous weights: 13 tons, 2.3 %
      - On freeboard deck: 12 tons
      - Above deck: 1 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     172 lbs / 78 Kg = 16.4 x 2.8 " / 70 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.22
   Metacentric height 1.0 ft / 0.3 m
   Roll period: 11.2 seconds
   Steadiness   - As gun platform (Average = 50 %): 71 %
         - Recoil effect (Restricted arc if above 1.00): 0.06
   Seaboat quality  (Average = 1.00): 1.00

Hull form characteristics:
   Hull has raised forecastle,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.400 / 0.410
   Length to Beam Ratio: 10.00 : 1
   'Natural speed' for length: 16.20 kts
   Power going to wave formation at top speed: 67 %
   Trim (Max stability = 0, Max steadiness = 100): 71
   Bow angle (Positive = bow angles forward): 10.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   21.00 %,  19.69 ft / 6.00 m,  18.04 ft / 5.50 m
      - Forward deck:   30.00 %,  9.84 ft / 3.00 m,  9.84 ft / 3.00 m
      - Aft deck:   34.00 %,  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:      11.70 ft / 3.57 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 174.6 %
      - Above water (accommodation/working, high = better): 139.0 %
   Waterplane Area: 4,241 Square feet or 394 Square metres
   Displacement factor (Displacement / loading): 47 %
   Structure weight / hull surface area: 21 lbs/sq ft or 104 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.47
      - Longitudinal: 1.95
      - Overall: 0.54
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform

1t -  FC
12t - 6 x 21" Torpedoes


Trials Speed after the new turbines and boilers are installed (original also had direct drive turbines so no need for electric drives):  32.5kts

[snip]

Ripping the engines out is going to be an expensive undertaking. What's the cost of the refit?

[TacCovert4]

I can't remember right off.  It's not particularly pretty, I think it came down to not all that much less than wholesale replacement.

[The Rock Doctor]

I think the cross-sectional hull strength will be a problem.  0.50 minimum is required?

[TacCovert4]

Shoot missed that.  There have only been a half-dozen variants of this refit worked on.....I'll have to find the correct one as it seems I picked an incorrect one.

And to answer Snip, this one's a proposal, but wholesale replacement is also possible, especially since we can now build full size DDs......

[snip]

IMO, replacement would be a better use of resources. Keep these ships around as-is until you have cause to rebuild with some ASW equipment.

[TacCovert4]

Well, since the Romans have been so insistent that I can do better than that  8)

I present to you all the replacement for the Scimitar Class, the "Open Beta" variant of a new GrosseTorpedoboot for the Aztec Navy.  Even has some tonnage that could be a quick refit for some ASW related items without much trouble at a future date.

TB-X, Aztec Torpedo Boat laid down 1915

Displacement:
   404 t light; 416 t standard; 452 t normal; 481 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (265.63 ft / 262.47 ft) x 21.33 ft x (6.89 / 7.18 ft)
   (80.96 m / 80.00 m) x 6.50 m  x (2.10 / 2.19 m)

Armament:
      3 - 2.76" / 70.0 mm 50.0 cal guns - 11.09lbs / 5.03kg shells, 160 per gun
     Quick firing guns in deck mounts, 1904 Model
     3 x Single mounts on centreline ends, majority aft
      2 raised mounts - superfiring
      8 - 0.31" / 8.0 mm 70.0 cal guns - 0.02lbs / 0.01kg shells, 2,000 per gun
     Machine guns in deck mounts, 1915 Model
     4 x Twin mounts on sides, evenly spread
      Weight of broadside 33 lbs / 15 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.79" / 20 mm         -               -

   - Conning towers: Forward 0.79" / 20 mm, Aft 0.00" / 0 mm

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 10,836 shp / 8,084 Kw = 28.90 kts
   Range 2,150nm at 12.00 kts
   Bunker at max displacement = 65 tons

Complement:
   48 - 63

Cost:
   £0.070 million / $0.281 million

Distribution of weights at normal displacement:
   Armament: 7 tons, 1.7 %
      - Guns: 7 tons, 1.7 %
   Armour: 6 tons, 1.4 %
      - Armament: 5 tons, 1.1 %
      - Conning Tower: 1 tons, 0.2 %
   Machinery: 229 tons, 50.8 %
   Hull, fittings & equipment: 132 tons, 29.1 %
   Fuel, ammunition & stores: 48 tons, 10.7 %
   Miscellaneous weights: 29 tons, 6.4 %
      - On freeboard deck: 27 tons
      - Above deck: 2 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     144 lbs / 65 Kg = 13.8 x 2.8 " / 70 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.21
   Metacentric height 0.7 ft / 0.2 m
   Roll period: 10.7 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.16
   Seaboat quality  (Average = 1.00): 1.01

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.410 / 0.418
   Length to Beam Ratio: 12.31 : 1
   'Natural speed' for length: 16.20 kts
   Power going to wave formation at top speed: 63 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 15.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  11.81 ft / 3.60 m,  10.83 ft / 3.30 m
      - Forward deck:   30.00 %,  10.83 ft / 3.30 m,  8.86 ft / 2.70 m
      - Aft deck:   35.00 %,  8.86 ft / 2.70 m,  8.20 ft / 2.50 m
      - Quarter deck:   15.00 %,  8.20 ft / 2.50 m,  8.20 ft / 2.50 m
      - Average freeboard:      9.41 ft / 2.87 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 168.5 %
      - Above water (accommodation/working, high = better): 125.7 %
   Waterplane Area: 3,466 Square feet or 322 Square metres
   Displacement factor (Displacement / loading): 52 %
   Structure weight / hull surface area: 20 lbs/sq ft or 97 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.36
      - Overall: 0.55
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room


27t 3 x 3 x 533mm TT Centerline behind bridge

1t - 1908 Fire Control

[The Rock Doctor]

Two superfiring mounts?

So it's a triple bank of torpedoes with two sets of reloads?

[TacCovert4]

The 'photo' arrangement would look something like this:

7cm Gun - Conning Tower - Triple 21in - Triple 21in - Triple 21in - Superfiring 7cm Gun - 7cm Gun.  Machine gun mounts are beside conning tower and superfiring gun. 

Superstructure consists of Conning Tower/Bridge (armored), a half-meter low superstructure 'swell' amidships with the TT on top (to allow for headroom on the deck below) and an aft 'pillar' with decking out and around for 2m past the Pillar to allow for working space for the 7cm gun searchlight (mounted fore of the gun) and protect anyone who might be on the deck below (like the other 7cm gun crew).  The pillar also terminates the superstructure 'swell' in the center.

The Conning Tower consists of a 1st Deck of general spaces (wardroom, captain's cabin, Corpsman's cabin (Wardroom is used as sickbay when needed), 2nd Deck is the main bridge and fire control, and the roof contains the rangefinder, searchlight, and a 'flying bridge' position for the captain to navigate from in good weather.  Corpsman's cabin and Wardroom are present as the Corpsman's cabin contains all of the medical supplies and the Wardroom is the sickbay when required.....and this way they're both behind some protection from damage.

And noting that....the TTs are strategically placed between the 20mm protected conning tower and the aft guns, each of which have 20mm of protection as well, to give them the most superstructure and armor between them and a likely direction where they could be hit by fire.

[snip]

Nasty amount of fish, but they are a little on the slow side. How much additional cost is it to get the design to 30knts?

[Desertfox]

And here I was going to suggest making them smaller, slower, and cheaper...

[TacCovert4]

Given the extra tonnage of the anticipated 1000t class to play with, Sultanate Designers set about designing a new more powerful destroyer using the equipment available to them.

DD-13, Aztec Destroyer laid down 1915

Displacement:
   994 t light; 1,054 t standard; 1,191 t normal; 1,299 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (326.36 ft / 321.52 ft) x 28.71 ft x (10.50 / 11.16 ft)
   (99.47 m / 98.00 m) x 8.75 m  x (3.20 / 3.40 m)

Armament:
      4 - 5.91" / 150 mm 50.0 cal guns - 109.02lbs / 49.45kg shells, 150 per gun
     Quick firing guns in deck mounts, 1915 Model
     4 x Single mounts on centreline, evenly spread
      2 raised mounts
      4 - 0.31" / 8.0 mm 60.0 cal guns - 0.02lbs / 0.01kg shells, 1,500 per gun
     Machine guns in deck mounts, 1915 Model
     2 x Twin mounts on centreline, forward evenly spread
      2 raised mounts
      Weight of broadside 436 lbs / 198 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   1.38" / 35 mm         -               -

   - Conning towers: Forward 1.38" / 35 mm, Aft 0.00" / 0 mm

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 21,601 shp / 16,114 Kw = 30.00 kts
   Range 3,280nm at 14.00 kts
   Bunker at max displacement = 245 tons

Complement:
   100 - 131

Cost:
   £0.200 million / $0.801 million

Distribution of weights at normal displacement:
   Armament: 83 tons, 7.0 %
      - Guns: 83 tons, 7.0 %
   Armour: 19 tons, 1.6 %
      - Armament: 15 tons, 1.3 %
      - Conning Tower: 3 tons, 0.3 %
   Machinery: 571 tons, 48.0 %
   Hull, fittings & equipment: 287 tons, 24.1 %
   Fuel, ammunition & stores: 196 tons, 16.5 %
   Miscellaneous weights: 35 tons, 2.9 %
      - On freeboard deck: 18 tons
      - Above deck: 17 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     326 lbs / 148 Kg = 3.2 x 5.9 " / 150 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.27
   Metacentric height 1.2 ft / 0.4 m
   Roll period: 11.1 seconds
   Steadiness   - As gun platform (Average = 50 %): 54 %
         - Recoil effect (Restricted arc if above 1.00): 0.69
   Seaboat quality  (Average = 1.00): 1.08

Hull form characteristics:
   Hull has rise forward of midbreak,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.430 / 0.442
   Length to Beam Ratio: 11.20 : 1
   'Natural speed' for length: 17.93 kts
   Power going to wave formation at top speed: 63 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 15.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  18.04 ft / 5.50 m,  16.40 ft / 5.00 m
      - Forward deck:   30.00 %,  16.40 ft / 5.00 m,  16.40 ft / 5.00 m
      - Aft deck:   35.00 %,  8.04 ft / 2.45 m,  8.04 ft / 2.45 m
      - Quarter deck:   15.00 %,  8.04 ft / 2.45 m,  8.04 ft / 2.45 m
      - Average freeboard:      12.35 ft / 3.77 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 174.1 %
      - Above water (accommodation/working, high = better): 131.4 %
   Waterplane Area: 5,796 Square feet or 538 Square metres
   Displacement factor (Displacement / loading): 62 %
   Structure weight / hull surface area: 30 lbs/sq ft or 145 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.53
      - Overall: 0.55
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room

18t - 2x3x 21in TT on Centerline

7t - 1908 FC

10t - Additional SR Radio

[snip]

I think a 1000t DD is going to be way to lively to handle 150s, expecialy superfiring 150s. .69 recoil is high, and thats a relative measurement.

[TacCovert4]

I think a 1000t DD is going to be way to lively to handle 150s, expecialy superfiring 150s. .69 recoil is high, and thats a relative measurement.

Posh!  The lads will just have to be quick on their feet.

[TacCovert4]

But to be serious,  it's a problem with the Aztec gun availability.   There is no gun between 10cm and 15cm in the inventory,  and there will not be an 11, 12, or 13cm gun for another couple of years.   So while a 15cm armed destroyer may not be ideal,  the punch compared to the equivalent 10cm destroyer is substantial.  And the Caribbean being typically a calm sea makes the conditions a little more favorable to a large gun destroyer.