Aztec Ship Designs 1918-1920

[Jefgte]

The lightening of the weight of the engines now makes possible to have powerful 6000t.
Range / speed excellent ... at the expense of the thickness high belt.

[TacCovert4]

The lightening of the weight of the engines now makes possible to have powerful 6000t.
Range / speed excellent ... at the expense of the thickness high belt.

Very true.  It seems that 1917 or so is the break point in SS where engines start lightening very quickly.  Back of napkin, as I haven't done anything in SS on it, if I wanted to do a reprise of the weapon class in 1919, or do a 3x2 variant of it at around that same 8000t mark, I could likely even get some noticeable TDS.  Of course I'm looking for where I can scrimp and save while still having an effective cruiser programme, since I'm not going to keep building light battlecruisers and am looking at possibilities for fast battleships in the 27-36,000t range which will cost a LOT more in the budget.  Plus all of the costs associated with trying to build 1500t DDs.

When we can get 1920 CL tech, that'll make things really interesting, as it will open the doors for Yubari-style cruisers and such.

[Kaiser Kirk]

And thus, a design with 5 single 180s, on roughly the tonnage of the Eagle Class, is commissioned for design:

Interesting.
Older forms of SS had a limit of 165mm for QF guns, which I discovered in N3, and is why that's the Parthian breakpoint.
I hadn't realized that seems to have been removed.  Blast now I need to design a new 180mm gun, mine is a BL.

Overall an interesting ship. I have a similar 1911 ship, albeit the 180mm are simple deck mounts - a deliberate "lesson" error.
and the 6000ts versions only made 28knots, it took 7500ts to manage 30.25kts.


As for fitting a TDS in a cruiser, I think you'll find it's very hard to do properly.
For a proper TDS, you need some standoff distance in the interior "bulges". For a 6000 ton ship, there generally won't be the beam
needed to allow a interior space of sufficient depth. Plus the narroring of the usable interior spaces "squeezes" the machinery and magazines - meaning adjusting forecastle/stern to provide the longer/heavier belt & TDS needed...and citadel armor deck.
However, this often uses up the ~130% available underwater space, which means stuff should be protruding above the WL.

Heavy cruisers like York/Kent actually had exterior bulges in addition to the interior space. The IJN and French had shallow interior, but that worked reasonably well. Overall they were not capital ship strength, but would contain sprung seams, mine damage, pt/aerial torpedo hits, and help Damage control vs. 'full' torpedoes.

... ok musing out :)

[TacCovert4]

And thus, a design with 5 single 180s, on roughly the tonnage of the Eagle Class, is commissioned for design:

Interesting.
Older forms of SS had a limit of 165mm for QF guns, which I discovered in N3, and is why that's the Parthian breakpoint.
I hadn't realized that seems to have been removed.  Blast now I need to design a new 180mm gun, mine is a BL.

Overall an interesting ship. I have a similar 1911 ship, albeit the 180mm are simple deck mounts - a deliberate "lesson" error.
and the 6000ts versions only made 28knots, it took 7500ts to manage 30.25kts.


As for fitting a TDS in a cruiser, I think you'll find it's very hard to do properly.
For a proper TDS, you need some standoff distance in the interior "bulges". For a 6000 ton ship, there generally won't be the beam
needed to allow a interior space of sufficient depth. Plus the narroring of the usable interior spaces "squeezes" the machinery and magazines - meaning adjusting forecastle/stern to provide the longer/heavier belt & TDS needed...and citadel armor deck.
However, this often uses up the ~130% available underwater space, which means stuff should be protruding above the WL.

Heavy cruisers like York/Kent actually had exterior bulges in addition to the interior space. The IJN and French had shallow interior, but that worked reasonably well. Overall they were not capital ship strength, but would contain sprung seams, mine damage, pt/aerial torpedo hits, and help Damage control vs. 'full' torpedoes.

... ok musing out :)

The gun thing might be on me.  Occasionally I'll run into SS telling me things like I can't have a QF 130mm gun, when I am absolutely certain that 1) I can and 2) I do and 3) It's allowed in the game rules.  I'll also occasionally run into 'ship has low composite strength' warnings when a ship meets the requirements for the .9 cruiser or DD rules.  So I've gotten in the habit of checking the actual numbers, and if SS is giving me a warning that doesn't match proper numbers, I'll delete the superfluous warning.  I'll double check on the 180, it is smack on the edge of where you CAN do a QF gun historically.  The reason, in fact, that I had picked the 7in rather than bumping up to 7.5 or 8in was because 7in was considered to be the edge of the QF capable guns historically, but I'm happy to make that minor change, no worries.

[Kaiser Kirk]

I would not worry about it.

I tinkered with SS, I think it's just the QF tag got changed between versions.
I just hadn't noticed the change and kept on the old course.

Confusingly there's several different ways they considered "QF" in regards to naval artillery..varying by navy.

As for the 180mm , Parthia uses it too. Pretty handy gun size.
I will note that the way ME/Shell wt works, a "modern" 180L50 will likely be kicking out a shell at 900mps, and have short barrel life, but good penetration.  That's why I've stepped down to 180L43, with a proportionately lower MV.

If you browse NavWeaps, a pattern starts coming apparently of nations looking for the largest hand load caliber...from the German 6.75" to the US 7", to the English 7.5" or French 194mm.
All suffer from declining ROF as combats move on, as the heavy shells wear down. Still, even after tapering down, ROF is reasonable, and train acceptable if single mounts. 
The comments regarding higher two -  194 / 7.5" seem to improve with power ramming and training, so modeling wise, they benefit more from powered (i.e. M&H) or turrets. What killed all of them was the Washington treaty, where reportedly the Japanese, with a physically smaller sailor, wanted to set the limit at 8" so that powered train and ramming in a turret would be needed by all, vs. say the Hawkins 7.5" where the Brits were making do with M&H.   I do find it curious the USA went with the 8" / 203mm howitzer, while the Soviets had both a 210mm ...and a 180mm.

But now I'm digressing all over your thread and making a mess :)

[TacCovert4]

I would not worry about it.

I tinkered with SS, I think it's just the QF tag got changed between versions.
I just hadn't noticed the change and kept on the old course.

Confusingly there's several different ways they considered "QF" in regards to naval artillery..varying by navy.

As for the 180mm , Parthia uses it too. Pretty handy gun size.
I will note that the way ME/Shell wt works, a "modern" 180L50 will likely be kicking out a shell at 900mps, and have short barrel life, but good penetration.  That's why I've stepped down to 180L43, with a proportionately lower MV.

If you browse NavWeaps, a pattern starts coming apparently of nations looking for the largest hand load caliber...from the German 6.75" to the US 7", to the English 7.5" or French 194mm.
All suffer from declining ROF as combats move on, as the heavy shells wear down. Still, even after tapering down, ROF is reasonable, and train acceptable if single mounts. 
The comments regarding higher two -  194 / 7.5" seem to improve with power ramming and training, so modeling wise, they benefit more from powered (i.e. M&H) or turrets. What killed all of them was the Washington treaty, where reportedly the Japanese, with a physically smaller sailor, wanted to set the limit at 8" so that powered train and ramming in a turret would be needed by all, vs. say the Hawkins 7.5" where the Brits were making do with M&H.   I do find it curious the USA went with the 8" / 203mm howitzer, while the Soviets had both a 210mm ...and a 180mm.

But now I'm digressing all over your thread and making a mess :)

Eh, it's fine.  Pretty much every pre-1920 ship is already designed, except for the final version of whatever will be the Capital Ship 1919 project, if I do one. 

I went with 180mm because based on my research that was the largest you could get a QF gun.  I regard it in the British sense of BL being Bag Loaded with separate shell and charge with interrupted screw breech, and QF being brass cased uniform charge with either a power breech or sliding breech.....with most QF also being single-piece ammo.  For my guns, I consider the 70s through 130s to be single-piece ammunition, my 150s-180s being two-piece with a rapid-operating breech (brass case means that the breech need be strong but not quite as perfectly sealed), and my 280s and up being bag loaded with a brass-cased base charge/primer (the Kaiserliche Marine model).  Copper and tin aren't hard for us to source, as we have local and Incan sources for them, and brass based/cased charges are both safer individually for handling and give a greater safety margin on the gun itself (the Sultanate being a relative newcomer to modern naval rifles).

In this last design, it's 180 singles in mount and hoist.  I consider those to be hand-loaded with powered hoists and loading trays/assists as part of the hoist structure, note that I don't do anything less than fully enclosed mounts for guns this size.  The 180 twin D&H on the Weapon class have specifically denoted 15t per mount for electric equipment, that's powered T&E as well as powered ramming (these are a lot like the US 'mounts' on interwar cruisers that were a halfway house to a turret, with the power equipment but not the multi-deck rotating structure).  My 130 twins would be powered hoists and trays, but hand-loaded/rammed, and my 100s, well those are hand-operated period (deck mount).  My consideration for a 'hoist' in the Springsharp guise, is a hoist mounted to the rotating structure (on/through main deck) with a handling room below that's not on a rotating structure (no turret stalk) with hoists to the magazine.  As the British called them with their 4.5in mounts, it's deck piercing but not multi-deck.  As part of the upper hoist, there's the loading tray which the crew rolls the shell/charge into and then whether it's powered or hand-rammed will be set by whether there is additional power equipment noted.  The reason my 180 twins have 15t of powered equipment is because without the electric turrets and power ramming, such a mount would quickly lose way compared to a single mount due to crew fatigue.

[TacCovert4]

After quite the 'difficult' gestation period, plans are finalized for the Destroyer-1918 program.  A lot of consideration was put towards yet another extension of the GTB program, but with Battleship 1919 still in process and the trio of heavy cruisers being built, it was considered to wait on a GTB run until budgetary requirements forced a return to the smaller vessels. 

The first, though second to be finalized, a 'cruiser destroyer' built specifically for wider-ranging Pacific operations and colonial use or escorting convoys.  Only a pair of these to be laid down in 1918, key 'features' are the extreme cruising range and survivability enhancements, a nod to long range operations.  Additionally, crew comfort was taken directly in hand with an expansion to the crew mess and larger and more extensive food preparatory spaces for crew morale and efficiency on long voyages.

DD-E, Aztec Destroyer-Cruiser laid down 1918

Displacement:
   1,500 t light; 1,567 t standard; 1,844 t normal; 2,065 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (391.10 ft / 387.14 ft) x 32.32 ft x (12.23 / 13.22 ft)
   (119.21 m / 118.00 m) x 9.85 m  x (3.73 / 4.03 m)

Armament:
      6 - 3.94" / 100 mm 50.0 cal guns - 32.30lbs / 14.65kg shells, 250 per gun
     Quick firing guns in deck mounts, 1918 Model
     3 x Twin mounts on centreline ends, majority aft
      1 raised mount aft - superfiring
      1 - 2.76" / 70.0 mm 50.0 cal gun - 11.09lbs / 5.03kg shells, 300 per gun
     Anti-air gun in deck mount, 1918 Model
     1 x Single mount on centreline, forward deck centre
      1 raised mount
      12 - 0.47" / 12.0 mm 70.0 cal guns - 0.07lbs / 0.03kg shells, 3,000 per gun
     Machine guns in deck mounts, 1918 Model
     12 x Single mounts on sides, evenly spread
      Weight of broadside 206 lbs / 93 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   1.06" / 27 mm         -               -

   - Box over magazines:
   1.06" / 27 mm

   - Conning towers: Forward 1.06" / 27 mm, Aft 0.00" / 0 mm

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 33,396 shp / 24,913 Kw = 32.00 kts
   Range 12,000nm at 10.00 kts
   Bunker at max displacement = 497 tons

Complement:
   139 - 182

Cost:
   £0.398 million / $1.592 million

Distribution of weights at normal displacement:
   Armament: 35 tons, 1.9 %
      - Guns: 35 tons, 1.9 %
   Armour: 25 tons, 1.4 %
      - Armament: 7 tons, 0.4 %
      - Armour Deck: 14 tons, 0.8 %
      - Conning Tower: 3 tons, 0.2 %
   Machinery: 965 tons, 52.3 %
   Hull, fittings & equipment: 397 tons, 21.5 %
   Fuel, ammunition & stores: 343 tons, 18.6 %
   Miscellaneous weights: 79 tons, 4.3 %
      - Hull above water: 28 tons
      - On freeboard deck: 24 tons
      - Above deck: 27 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     439 lbs / 199 Kg = 14.4 x 3.9 " / 100 mm shells or 0.3 torpedoes
   Stability (Unstable if below 1.00): 1.30
   Metacentric height 1.5 ft / 0.4 m
   Roll period: 11.2 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.21
   Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.422 / 0.437
   Length to Beam Ratio: 11.98 : 1
   'Natural speed' for length: 19.68 kts
   Power going to wave formation at top speed: 61 %
   Trim (Max stability = 0, Max steadiness = 100): 68
   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 %,  14.76 ft / 4.50 m,  13.78 ft / 4.20 m
      - Forward deck:   30.00 %,  13.78 ft / 4.20 m,  13.12 ft / 4.00 m
      - Aft deck:   35.00 %,  13.12 ft / 4.00 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:      12.37 ft / 3.77 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 177.5 %
      - Above water (accommodation/working, high = better): 132.6 %
   Waterplane Area: 7,809 Square feet or 725 Square metres
   Displacement factor (Displacement / loading): 70 %
   Structure weight / hull surface area: 29 lbs/sq ft or 142 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 0.89
      - Overall: 0.53
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform

4t - 1912 FC

25t - LR Radio

24t - 2 x 3 x 18in TT on Centerline, 2 x Reload Salvo

14t - Crew Comfort Improvements

12t - Additional Pumps and DC Equipment

Trial Speed - 32.65kts

[TacCovert4]

The other, a fairly standard design 'fleet destroyer' with multi-role capabilities and utilizing the heavier firepower of the new 130mm guns for the first time in an Aztec destroyer design. 

DD-D, Aztec Destroyer laid down 1918

Displacement:
   1,500 t light; 1,579 t standard; 1,815 t normal; 2,004 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (391.71 ft / 387.14 ft) x 32.28 ft x (11.96 / 12.80 ft)
   (119.39 m / 118.00 m) x 9.84 m  x (3.65 / 3.90 m)

Armament:
      5 - 5.12" / 130 mm 50.0 cal guns - 70.97lbs / 32.19kg shells, 200 per gun
     Quick firing guns in deck mounts, 1918 Model
     4 x Single mounts on centreline ends, evenly spread
      2 raised mounts - superfiring
     1 x Single mount on centreline, aft deck forward
      1 - 2.76" / 70.0 mm 50.0 cal gun - 11.09lbs / 5.03kg shells, 300 per gun
     Anti-air gun in deck mount, 1918 Model
     1 x Single mount on centreline, forward deck aft
      1 raised mount
      8 - 0.47" / 12.0 mm 70.0 cal guns - 0.07lbs / 0.03kg shells, 3,000 per gun
     Machine guns in deck mounts, 1918 Model
     4 x Twin mounts on sides, evenly spread
      Weight of broadside 366 lbs / 166 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.98" / 25 mm         -               -

   - Conning towers: Forward 0.98" / 25 mm, Aft 0.00" / 0 mm

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 35,819 shp / 26,721 Kw = 32.61 kts
   Range 4,980nm at 14.00 kts
   Bunker at max displacement = 425 tons

Complement:
   138 - 180

Cost:
   £0.417 million / $1.667 million

Distribution of weights at normal displacement:
   Armament: 71 tons, 3.9 %
      - Guns: 71 tons, 3.9 %
   Armour: 16 tons, 0.9 %
      - Armament: 13 tons, 0.7 %
      - Conning Tower: 3 tons, 0.2 %
   Machinery: 973 tons, 53.6 %
   Hull, fittings & equipment: 396 tons, 21.8 %
   Fuel, ammunition & stores: 315 tons, 17.3 %
   Miscellaneous weights: 44 tons, 2.4 %
      - Hull below water: 5 tons
      - Hull above water: 5 tons
      - On freeboard deck: 30 tons
      - Above deck: 4 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     400 lbs / 182 Kg = 6.0 x 5.1 " / 130 mm shells or 0.3 torpedoes
   Stability (Unstable if below 1.00): 1.29
   Metacentric height 1.4 ft / 0.4 m
   Roll period: 11.3 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.39
   Seaboat quality  (Average = 1.00): 1.01

Hull form characteristics:
   Hull has rise forward of midbreak,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.425 / 0.438
   Length to Beam Ratio: 11.99 : 1
   'Natural speed' for length: 19.68 kts
   Power going to wave formation at top speed: 62 %
   Trim (Max stability = 0, Max steadiness = 100): 70
   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 %,  17.06 ft / 5.20 m,  17.06 ft / 5.20 m
      - Forward deck:   30.00 %,  17.06 ft / 5.20 m,  17.06 ft / 5.20 m
      - Aft deck:   35.00 %,  8.20 ft / 2.50 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:      12.63 ft / 3.85 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 185.1 %
      - Above water (accommodation/working, high = better): 132.7 %
   Waterplane Area: 7,820 Square feet or 726 Square metres
   Displacement factor (Displacement / loading): 64 %
   Structure weight / hull surface area: 31 lbs/sq ft or 149 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 0.98
      - Overall: 0.53
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform

24t - 2x3x 21in HW TT on Centerline
6t - 60 x ASW Harpoons and Lockers (planned for refit to other ASW weapons at future date)

9t - 1912 FC
5t - Space Set Aside for Hydrophones

Trial Speed - 33.28kts

[TacCovert4]

Two designs for the 1918 Aztec GTB.  The first, an update of the GTB-W style, with the new heavyweight 21in TT installed to give more torpedo range.  Speed had to be slightly cut to make the upgrade.

TB-X, Aztec Torpedo Boat laid down 1918

Displacement:
   500 t light; 515 t standard; 566 t normal; 606 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (286.39 ft / 283.14 ft) x 23.62 ft x (7.22 / 7.56 ft)
   (87.29 m / 86.30 m) x 7.20 m  x (2.20 / 2.30 m)

Armament:
      3 - 2.76" / 70.0 mm 50.0 cal guns - 11.08lbs / 5.03kg shells, 200 per gun
     Quick firing guns in deck mounts, 1918 Model
     3 x Single mounts on centreline ends, majority forward
      1 raised mount - superfiring
      8 - 0.47" / 12.0 mm 70.0 cal guns - 0.06lbs / 0.03kg shells, 2,000 per gun
     Machine guns in deck mounts, 1918 Model
     4 x Twin mounts on sides, evenly spread
      Weight of broadside 34 lbs / 15 kg

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 18,796 shp / 14,022 Kw = 32.10 kts
   Range 2,950nm at 12.00 kts
   Bunker at max displacement = 90 tons

Complement:
   57 - 75

Cost:
   £0.125 million / $0.499 million

Distribution of weights at normal displacement:
   Armament: 8 tons, 1.3 %
      - Guns: 8 tons, 1.3 %
   Machinery: 306 tons, 54.1 %
   Hull, fittings & equipment: 165 tons, 29.3 %
   Fuel, ammunition & stores: 66 tons, 11.6 %
   Miscellaneous weights: 21 tons, 3.7 %
      - On freeboard deck: 20 tons
      - Above deck: 1 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     151 lbs / 68 Kg = 14.4 x 2.8 " / 70 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.14
   Metacentric height 0.7 ft / 0.2 m
   Roll period: 11.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 58 %
         - Recoil effect (Restricted arc if above 1.00): 0.10
   Seaboat quality  (Average = 1.00): 0.76

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.410 / 0.419
   Length to Beam Ratio: 11.99 : 1
   'Natural speed' for length: 16.83 kts
   Power going to wave formation at top speed: 67 %
   Trim (Max stability = 0, Max steadiness = 100): 76
   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 %,  12.14 ft / 3.70 m,  11.32 ft / 3.45 m
      - Forward deck:   30.00 %,  11.32 ft / 3.45 m,  9.02 ft / 2.75 m
      - Aft deck:   35.00 %,  9.02 ft / 2.75 m,  8.37 ft / 2.55 m
      - Quarter deck:   15.00 %,  8.37 ft / 2.55 m,  8.37 ft / 2.55 m
      - Average freeboard:      9.68 ft / 2.95 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 178.6 %
      - Above water (accommodation/working, high = better): 129.8 %
   Waterplane Area: 4,142 Square feet or 385 Square metres
   Displacement factor (Displacement / loading): 40 %
   Structure weight / hull surface area: 22 lbs/sq ft or 109 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.16
      - Overall: 0.54
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room
   Poor seaboat, wet and uncomfortable, reduced performance in heavy weather


20t - 1x3x21in HW TT Centerline ; 2 x 1 HW TT Fixed Forward

1t - 1908 Fire Control

[TacCovert4]

The second, and update along the lines of the GTB-Z, but with the Heavyweight torpedo.

TB-X, Aztec Torpedo Boat laid down 1918

Displacement:
   500 t light; 515 t standard; 568 t normal; 610 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (286.67 ft / 283.46 ft) x 23.62 ft x (7.81 / 8.17 ft)
   (87.38 m / 86.40 m) x 7.20 m  x (2.38 / 2.49 m)

Armament:
      3 - 2.76" / 70.0 mm 50.0 cal guns - 11.08lbs / 5.03kg shells, 200 per gun
     Quick firing guns in deck mounts, 1918 Model
     2 x Single mounts on centreline, forward evenly spread
      1 raised mount
     1 x Single mount on centreline, aft deck forward
      1 raised mount aft
      8 - 0.31" / 8.0 mm 70.0 cal guns - 0.02lbs / 0.01kg shells, 2,000 per gun
     Machine guns in deck mounts, 1918 Model
     4 x Twin mounts on sides, evenly spread
      Weight of broadside 33 lbs / 15 kg

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 17,123 shp / 12,774 Kw = 31.55 kts
   Range 3,100nm at 12.00 kts
   Bunker at max displacement = 95 tons

Complement:
   57 - 75

Cost:
   £0.124 million / $0.495 million

Distribution of weights at normal displacement:
   Armament: 7 tons, 1.3 %
      - Guns: 7 tons, 1.3 %
   Machinery: 302 tons, 53.2 %
   Hull, fittings & equipment: 165 tons, 29.1 %
   Fuel, ammunition & stores: 68 tons, 12.0 %
   Miscellaneous weights: 25 tons, 4.4 %
      - On freeboard deck: 24 tons
      - Above deck: 1 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     149 lbs / 68 Kg = 14.2 x 2.8 " / 70 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.05
   Metacentric height 0.6 ft / 0.2 m
   Roll period: 12.5 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.15
   Seaboat quality  (Average = 1.00): 0.84

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.380 / 0.390
   Length to Beam Ratio: 12.00 : 1
   'Natural speed' for length: 16.84 kts
   Power going to wave formation at top speed: 65 %
   Trim (Max stability = 0, Max steadiness = 100): 83
   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 %,  11.98 ft / 3.65 m,  11.15 ft / 3.40 m
      - Forward deck:   30.00 %,  11.15 ft / 3.40 m,  9.02 ft / 2.75 m
      - Aft deck:   35.00 %,  9.02 ft / 2.75 m,  8.37 ft / 2.55 m
      - Quarter deck:   15.00 %,  8.37 ft / 2.55 m,  8.37 ft / 2.55 m
      - Average freeboard:      9.62 ft / 2.93 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 175.6 %
      - Above water (accommodation/working, high = better): 126.9 %
   Waterplane Area: 4,067 Square feet or 378 Square metres
   Displacement factor (Displacement / loading): 44 %
   Structure weight / hull surface area: 22 lbs/sq ft or 109 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.20
      - Overall: 0.54
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform
   Poor seaboat, wet and uncomfortable, reduced performance in heavy weather


24t - 3 x 3 x 533mm HW TT Centerline

1t - 1908 Fire Control

[TacCovert4]

And the third, maintaining the standard 21in torpedo.

TB-X, Aztec Torpedo Boat laid down 1918

Displacement:
   500 t light; 515 t standard; 568 t normal; 610 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (286.67 ft / 283.46 ft) x 23.62 ft x (7.81 / 8.17 ft)
   (87.38 m / 86.40 m) x 7.20 m  x (2.38 / 2.49 m)

Armament:
      3 - 2.76" / 70.0 mm 50.0 cal guns - 11.08lbs / 5.03kg shells, 200 per gun
     Quick firing guns in deck mounts, 1918 Model
     2 x Single mounts on centreline, forward evenly spread
      1 raised mount
     1 x Single mount on centreline, aft deck forward
      1 raised mount aft
      8 - 0.31" / 8.0 mm 70.0 cal guns - 0.02lbs / 0.01kg shells, 2,000 per gun
     Machine guns in deck mounts, 1918 Model
     4 x Twin mounts on sides, evenly spread
      Weight of broadside 33 lbs / 15 kg

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 18,185 shp / 13,566 Kw = 32.00 kts
   Range 3,100nm at 12.00 kts
   Bunker at max displacement = 95 tons

Complement:
   57 - 75

Cost:
   £0.125 million / $0.499 million

Distribution of weights at normal displacement:
   Armament: 7 tons, 1.3 %
      - Guns: 7 tons, 1.3 %
   Machinery: 306 tons, 53.9 %
   Hull, fittings & equipment: 167 tons, 29.5 %
   Fuel, ammunition & stores: 68 tons, 12.0 %
   Miscellaneous weights: 19 tons, 3.3 %
      - On freeboard deck: 18 tons
      - Above deck: 1 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     147 lbs / 67 Kg = 14.0 x 2.8 " / 70 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.07
   Metacentric height 0.7 ft / 0.2 m
   Roll period: 12.3 seconds
   Steadiness   - As gun platform (Average = 50 %): 67 %
         - Recoil effect (Restricted arc if above 1.00): 0.14
   Seaboat quality  (Average = 1.00): 0.81

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.380 / 0.390
   Length to Beam Ratio: 12.00 : 1
   'Natural speed' for length: 16.84 kts
   Power going to wave formation at top speed: 66 %
   Trim (Max stability = 0, Max steadiness = 100): 83
   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 %,  11.98 ft / 3.65 m,  11.15 ft / 3.40 m
      - Forward deck:   30.00 %,  11.15 ft / 3.40 m,  9.02 ft / 2.75 m
      - Aft deck:   35.00 %,  9.02 ft / 2.75 m,  8.37 ft / 2.55 m
      - Quarter deck:   15.00 %,  8.37 ft / 2.55 m,  8.37 ft / 2.55 m
      - Average freeboard:      9.62 ft / 2.93 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 177.8 %
      - Above water (accommodation/working, high = better): 126.9 %
   Waterplane Area: 4,067 Square feet or 378 Square metres
   Displacement factor (Displacement / loading): 42 %
   Structure weight / hull surface area: 23 lbs/sq ft or 111 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.22
      - Overall: 0.54
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room
   Poor seaboat, wet and uncomfortable, reduced performance in heavy weather


18t - 2 x 3 x 533mm  TT Centerline

1t - 1908 Fire Control

[Jefgte]

Heavier torpedo armament is better, but...

Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

=> Not cool for battle & crew performances.

[TacCovert4]

Heavier torpedo armament is better, but...

Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

=> Not cool for battle & crew performances.

No, it's not ideal, as snip's 1000t DDs found out when they tried to survive a full-blown seaway in 1913 during a hurricane with .75 seakeeping.

However, for a ship that is principally only built/suited for home waters and the Caribbean, .8 seakeeping is going to be passable as the average wave height in the Caribbean/Gulf is around 4ft with significant wave height around 6-8ft in non-hurricane areas....vice the 11ft average and 17ft significant non-storm wave height in the Atlantic (where SS 1.0 Seakeeping seems to be denoted for). 

Basically, no I can't send GTBs out into the teeth of a Category 2 Hurricane like I could a Battleship or something.  But then they're not long ranged ships with high endurance, so they're meant to stay within several hundreds of miles from a port.

Overall, the purpose of a GTB is threefold:

1)  Be a cheap and cheerful fast combatant for putting significant numbers of torpedoes in the water at minimal risk to expensive assets.  500t is functionally the smallest you can do with a significant torpedo loadout, and the biggest you can do without significant time/yard investment.  500t ships are also low-slung, and even the slowest of the proposed designs is able to push 34kts in Caribbean style waters (31.55kts in a Seaway), the fastest is 34.5kts.   While you could get the same 6 torpedoes in the water with say 120 tons worth of torpedo boat, those torpedoes are not the long-range HW torpedoes, and possibly not even 21in torpedoes at all (or the aviation variation with shorter range than even the standard 21in torp).  And since MTBs don't have fire control, you're firing forward tubes from an MTB running flat out and basically being aimed like a longbow by the boat's captain at suicide ranges.  A GTB, in say a night engagement, can launch its torpedoes from destroyer ranges that could be almost double the maximum launch range of an MTB, and can do so with the benefit of full aiming systems, rangefinders, scopes, etc.

2)  Be MTB Leaders.  GTBs have Comms.  Which means that they operate in the fleet like DDs.  And means that they can both send and receive signals like a destroyer.  Put a GTB leading an MTB squadron, and now that MTB squadron isn't just running about with whatever plan they happened to get at base, or whatever they can get via semaphore or flags from a passing ship.  They have direction to operate with, and can be redeployed to an advantageous position (one of the failings at Ironclad Bay was that my MTBs wound up having to go THROUGH my fleet.  If they had had a GTB division leading them, they could have been notified and swung around, catching the Roman fleet in a crossfire where they'd either have to make a difficult maneuver in tight waters and risk running aground, or handle the MTBs that would now be moving much faster and attacking them from an advantageous angle).

3)  Be MTB Killers.  Obviously MTBs are ideally suited to the Caribbean and Gulf.  High Speed, lots of island chains, hard to spot, relatively calm.  GTBs have both a main armament specifically tailored to fighting MTBs (100mm or 70mm guns depending on model) efficiently, they have FC systems unlike MTBs, so they can get more reliable hits from further out, and they have one other minor edge over larger combatants.  They have a shallow draft.  2.25m is a REALLY shallow draft.  Most torpedoes need to be drafting 3m or so in order to guarantee getting under wave troughs and into water where their depth keeping is functional.  Shallow running torpedoes have a tendency to porpoise and do other stupid mess.  So while it's no guarantee that a GTB can't take a devastating torpedo hit, I'd be willing to hazard that the majority of torpedoes fired at a GTB would be wasted either through the ship's extreme maneuverability and speed....or simply by zipping harmlessly beneath the keel.

[The Rock Doctor]

And yet I see no miscellaneous weight allocated for cheerfulness, curious.

[TacCovert4]

And yet I see no miscellaneous weight allocated for cheerfulness, curious.

Kind of like RL Marines, they run on a steady diet of caffeine,  nicotine,  and discontent