Parthian vessels 1916 onwards

[Kaiser Kirk]

Nothing wrong with small and reasonable.  That's why I have a swarm of GTBs in service.  I needed something 'dd-ish', I needed a lot of them, and I couldn't afford to wait due to losses in the Caicos War.  So I build 500 tonners en masse to create the DD-like torpedo threat and as close to a DD gun threat as possible for literal peanuts.

As I mentioned elsewhere I'm looking at 3 different broad types of Destroyers. The Oceanic for longer range ops, the 'Fleet' which needs numbers and utility roles, and then a 'Coastal' which will echo what you describe.  I want the 'Coastal' to be more of a 'Torpedo boat' able to make a long range, high speed 'sweep' and return to base, providing a viable gun and torpedo threat.
Operating out of bases like Salahah in the Gulf of Aden, Stone town and Sofala -bracketing the Straits of Madagascar, Aceh and Palembang and Borneo, Jamaica and Trinidad.

[Kaiser Kirk]

As for torpedo sizes the other advantage a 21" torpedo has is range. Japan didnt go with heavy 21" for warhead size but for range and speed capabilities. You can either hit them from further away, or you can hit them faster from the same range. Or you go with batteries and hit them silently from closer up.

With the way hit % drops off with range, I'm not certain how viable long range torpedo attacks are..or were. The early long lance were initially successful, but that was with 1940s targeting, and targets that didn't realize a torpedo was en route. Later long lance hit ranges dropped considerably.

Range is consideration still - and speed, and the 21" historicals have that.
This is one reason I need to find time to delve into my book on torpedoes and match it to our tech table.
The table doesn't say "historical 21" torp", it has the torpedo diameter, and the types of torpedo tech in use - like wet heater.
The way the tech table is constructed there is no particular reason you couldn't field a 16" with advanced wet heater engines and an advanced fuse. Which might give better ranges for lightwieght torpedoes - But teasing apart what that means is a little rough, so we're just using historical for now.

[Kaiser Kirk]

The 4x120mm design seems more optimized for a defensive role than an offensive one.

I suppose you could swap out two triple 18" carriages for a pair of double 21". 

You're having the same problem with destroyer guns that I have with cruiser guns:  Big gap in the inventory, lack of time/funding to fix it.

So thinking about Rocky's initial question, while I had thought it through,
I got to wondering if I was missing the obvious.
...I'm not limited to 1,000 tons.

Heck I said I wanted a 1000-1200.

So what was the opportunity cost of those 6 tons?
Heck, lets get the construction reserve up to 15t like I wanted.

Apparently that all costs ...43 tons.
or $0.0043 and 0.0043BP
That might...just might...be affordable.

So I need to redo the range at speed calcs, but here's the revised ship.

Fleet Destroyer, Parthian Empire Fleet Destroyer laid down 1919

Displacement:
   1,043 t light; 1,097 t standard; 1,274 t normal; 1,416 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (325.48 ft / 321.52 ft) x 30.61 ft x (10.66 / 11.51 ft)
   (99.21 m / 98.00 m) x 9.33 m  x (3.25 / 3.51 m)

Armament:
      4 - 4.72" / 120 mm 43.0 cal guns - 55.12lbs / 25.00kg shells, 200 per gun
     Quick firing guns in deck mounts, 1919 Model
     4 x Single mounts on centreline ends, evenly spread
      2 raised mounts - superfiring
      1 - 3.54" / 90.0 mm 50.0 cal gun - 24.25lbs / 11.00kg shells, 300 per gun
     Anti-air gun in deck mount, 1919 Model
     1 x Single mount on centreline, aft deck forward
      1 raised mount
      Weight of broadside 245 lbs / 111 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.24" / 6 mm         -               -
   2nd:   0.24" / 6 mm         -               -

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 1 shaft, 24,010 shp / 17,912 Kw = 30.40 kts Trial Speed: 31.3
   Range 4,800nm at 14.00 kts
   Bunker at max displacement = 319 tons

Complement:
   106 - 138

Cost:
   £0.298 million / $1.193 million

Distribution of weights at normal displacement:
   Armament: 39 tons, 3.1 %
      - Guns: 39 tons, 3.1 %
   Armour: 3 tons, 0.2 %
      - Armament: 3 tons, 0.2 %
   Machinery: 639 tons, 50.1 %
   Hull, fittings & equipment: 295 tons, 23.2 %
   Fuel, ammunition & stores: 231 tons, 18.1 %
   Miscellaneous weights: 67 tons, 5.2 %
      - Hull below water: 15 tons
      - Hull void weights: 15 tons
      - Hull above water: 7 tons
      - On freeboard deck: 26 tons
      - Above deck: 4 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     366 lbs / 166 Kg = 6.9 x 4.7 " / 120 mm shells or 0.3 torpedoes
   Stability (Unstable if below 1.00): 1.51
   Metacentric height 1.7 ft / 0.5 m
   Roll period: 9.8 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.26
   Seaboat quality  (Average = 1.00): 1.00

Hull form characteristics:
   Hull has a flush deck,
     a ram bow and a cruiser stern
   Block coefficient (normal/deep): 0.425 / 0.437
   Length to Beam Ratio: 10.50 : 1
   'Natural speed' for length: 17.93 kts
   Power going to wave formation at top speed: 64 %
   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 %,  14.76 ft / 4.50 m,  13.12 ft / 4.00 m
      - Forward deck:   35.00 %,  13.12 ft / 4.00 m,  11.48 ft / 3.50 m
      - Aft deck:   30.00 %,  11.48 ft / 3.50 m,  11.48 ft / 3.50 m
      - Quarter deck:   15.00 %,  11.48 ft / 3.50 m,  11.48 ft / 3.50 m
      - Average freeboard:      12.23 ft / 3.73 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 173.2 %
      - Above water (accommodation/working, high = better): 125.2 %
   Waterplane Area: 5,843 Square feet or 543 Square metres
   Displacement factor (Displacement / loading): 68 %
   Structure weight / hull surface area: 29 lbs/sq ft or 139 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.31
      - Overall: 0.55
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room

Intended as a potential  Fleet destroyer.

Excellent seakeeping from a raised forecastle.
Range to reach a base and return at fleet speeds

Good light gun armanent
AA gun 
Heavy torpedo loadout
Enhanced Hydrophones for an ASW role

                                                   DC
A(B)          TT(AA)TT          (X) Y
                                                   DC

Range @ Speeds :
29.5kts(90%) :  605nm (20hrs)
25.5kts (50%) : 955nm (37hrs)
16kts : 3,400nm

With the fleet at 12-14knots,
14 or 16 knots allows reasonable range when working with the fleet from bases.

The ability to make a 36hr sweep of 900m allows
them to interdict substantial areas, acting as Coastal Torpedo boats for that purpose.



Misc wt :
6t     Reserve Wt.
3.9FC
12t   2TT3 18"
8t     DC
1t     CO2 A/C
1t     ASW Kite
5t     Paravanes
15t   Enhanced Hydrophone package

[Kaiser Kirk]

Here's a 3rd Version of that Destroyer.

Having answered that the opportunity cost of 21" torps and +9t const reserve was 43 tons,

I asked what the cost of +0.6knots was..that was more, +100tons.

Not sure 0.6knots (+0.54 trial speed) is worth that to me,
basically that's building 10xVersion 3 vs. 11xVersion 2  - 40x120+60x21"+3900 float vs. 44x120+66x21"+4026 float
Theoretically the Version 2 squadron would be more dangerous an adversary
...or I can shave 1000 tons elsewhere.

Of course if I build ~80 of these, then that's 80x V3  against 80 V2 + 2 cruisers.

Fleet Destroyer v3., Parthian Empire Fleet Destroyer laid down 1919

Displacement:
   1,143 t light; 1,199 t standard; 1,385 t normal; 1,534 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (337.01 ft / 333.01 ft) x 31.99 ft x (11.32 / 12.16 ft)
   (102.72 m / 101.50 m) x 9.75 m  x (3.45 / 3.71 m)

Armament:
      4 - 4.72" / 120 mm 43.0 cal guns - 55.12lbs / 25.00kg shells, 200 per gun
     Quick firing guns in deck mounts, 1919 Model
     4 x Single mounts on centreline ends, evenly spread
      2 raised mounts - superfiring
      1 - 3.54" / 90.0 mm 50.0 cal gun - 24.25lbs / 11.00kg shells, 300 per gun
     Anti-air gun in deck mount, 1919 Model
     1 x Single mount on centreline, aft deck forward
      1 raised mount
      Weight of broadside 245 lbs / 111 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.24" / 6 mm         -               -
   2nd:   0.24" / 6 mm         -               -

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 1 shaft, 26,621 shp / 19,859 Kw = 31.00 kts
   Range 4,800nm at 14.00 kts
   Bunker at max displacement = 335 tons

Complement:
   113 - 147

Cost:
   £0.327 million / $1.308 million

Distribution of weights at normal displacement:
   Armament: 39 tons, 2.8 %
      - Guns: 39 tons, 2.8 %
   Armour: 3 tons, 0.2 %
      - Armament: 3 tons, 0.2 %
   Machinery: 709 tons, 51.2 %
   Hull, fittings & equipment: 325 tons, 23.5 %
   Fuel, ammunition & stores: 242 tons, 17.5 %
   Miscellaneous weights: 67 tons, 4.8 %
      - Hull below water: 15 tons
      - Hull void weights: 15 tons
      - Hull above water: 7 tons
      - On freeboard deck: 26 tons
      - Above deck: 4 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     390 lbs / 177 Kg = 7.4 x 4.7 " / 120 mm shells or 0.3 torpedoes
   Stability (Unstable if below 1.00): 1.54
   Metacentric height 1.9 ft / 0.6 m
   Roll period: 9.8 seconds
   Steadiness   - As gun platform (Average = 50 %): 51 %
         - Recoil effect (Restricted arc if above 1.00): 0.23
   Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
   Hull has a flush deck,
     a ram bow and a cruiser stern
   Block coefficient (normal/deep): 0.402 / 0.414
   Length to Beam Ratio: 10.41 : 1
   'Natural speed' for length: 18.25 kts
   Power going to wave formation at top speed: 64 %
   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 %,  14.93 ft / 4.55 m,  13.45 ft / 4.10 m
      - Forward deck:   40.00 %,  13.45 ft / 4.10 m,  11.65 ft / 3.55 m
      - Aft deck:   25.00 %,  11.65 ft / 3.55 m,  11.65 ft / 3.55 m
      - Quarter deck:   15.00 %,  11.65 ft / 3.55 m,  11.65 ft / 3.55 m
      - Average freeboard:      12.49 ft / 3.81 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): 127.7 %
   Waterplane Area: 6,209 Square feet or 577 Square metres
   Displacement factor (Displacement / loading): 67 %
   Structure weight / hull surface area: 30 lbs/sq ft or 144 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.29
      - Overall: 0.55
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room

Intended as a potential  Fleet destroyer.

Range to reach a base and return at fleet speeds

Good light gun armanent
AA gun 
Heavy torpedo loadout
Enhanced Hydrophones for an ASW role

                                                   DC
A(B)          TT(AA)TT          (X) Y
                                                   DC

Range @ Speeds :
335t max bunker
2200nm at 10knots : 82t to "get home"
So 275t are available for offensive operations,
more if "home" is close.

90% power is 23,959shp, or 30.23kts.
50% power is 11,980shp, or 25.52knots

275t fuel is good for :
470nm @ 30.23knts = 15hrs.
797nm @ 25.5knots = 31.25hrs
2840nm @ 16knots = 177.5hrs / 7.4 days



With the fleet at 12-14knots,
14 or 16 knots allows reasonable range when working with the fleet from bases.

The ability to make a 36hr sweep of 900m allows
them to interdict substantial areas, acting as Coastal Torpedo boats for that purpose.



Misc wt :
15t     Reserve Wt.
3.9FC
18t   2TT3 21"
8t     DC
1t     CO2 A/C
1t     ASW Kite
5t     Paravanes
15t   Enhanced Hydrophone package

[The Rock Doctor]

Does the game system see any distinction between the two so far as shells-to-sink are concerned?

Anyway, I think the additional tonnage is well-spent.  More capable armament, the additional speed marginally increases its ability to be in the right place at the right time.

[Kaiser Kirk]

Floatation is about the same at 366 vs. 390,
In terms of shell damage, even if not criticaled, performance erodes as damage is taken,
so what sinks one, makes floating wreckage of the other.
The Oceanic DD at 1500 tons and nearly 600 floatation has sufficiently more to matter.

I'll have to think on it, as I am thinking in the 80 range, which would mean the difference can afford 2 of those escort cruisers

But I appreciate being prodded to explore these questions :)

[Kaiser Kirk]

And then the Coastal Destroyer concept...which I'm not happy with.
I've managed a 600tonner by severely restricting the armanent and performance.

This is a 800tonner that manages all the things I want,
but I am aware it's slightly larger than most of my existing DDs.

Based in Trinadad, Jamaica, Cape Horn, Sofala, Dar Es Salaam, Salahah, Colombo, Aceh, Palembang, Tarakan, and Balikipapan, they could effect a great number of important supply routes.... so I need them cheap. That may be more important than capable.

Intended as a coastal destroyer, operating from naval bases or even tenders in shallow waters, in coves, or up shallow rivers, hidden from the foe.

They are intended to interdict sea routes or force the foe to devote significant assets to guard them. They are not expected to operate in storms, but have sufficient seakeeping for bluewater operations.


They are partially coal-burning to allow them to operate from
cut off bases if necessary, saving potentially scarce fuel oil for
combat missions.

Trial Speed : 31.18kts

27.98 : Speed on just oil
21.333 : Speed on just oil-sprayed coal

Coal bunkerage : 70t
Range on Coal at 21kts : 380nm
Range on Coal at 10kts : 2,250nm

Max Bunker : 304t
  23t :  528nm @ 10ts "go home"
202t : 1,056nm 48hrs @ 22knots 
  79t : 152nm @ 30kts = 5hours


Cobra, Parthian Coastal Destroyer laid down 1920

Displacement:
   800 t light; 833 t standard; 1,002 t normal; 1,137 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (314.96 ft / 314.96 ft) x 28.54 ft x (10.17 / 11.08 ft)
   (96.00 m / 96.00 m) x 8.70 m  x (3.10 / 3.38 m)

Armament:
      4 - 3.54" / 90.0 mm 45.0 cal guns - 22.05lbs / 10.00kg shells, 200 per gun
     Breech loading guns in deck mounts, 1920 Model
     4 x Single mounts on centreline ends, evenly spread
      2 raised mounts - superfiring
      1 - 3.54" / 90.0 mm 50.0 cal gun - 24.25lbs / 11.00kg shells, 200 per gun
     Anti-air gun in deck mount, 1920 Model
     1 x Single mount on centreline, aft deck forward
      Weight of broadside 112 lbs / 51 kg

Machinery:
   Coal and oil fired boilers, steam turbines,
   Direct drive, 1 shaft, 19,073 shp / 14,229 Kw = 30.00 kts
   Range 1,610nm at 22.00 kts
   Bunker at max displacement = 304 tons (23% coal)

Complement:
   88 - 115

Cost:
   £0.246 million / $0.985 million

Distribution of weights at normal displacement:
   Armament: 19 tons, 1.9 %
      - Guns: 19 tons, 1.9 %
   Machinery: 504 tons, 50.3 %
   Hull, fittings & equipment: 233 tons, 23.2 %
   Fuel, ammunition & stores: 201 tons, 20.1 %
   Miscellaneous weights: 45 tons, 4.5 %
      - Hull below water: 6 tons
      - Hull void weights: 5 tons
      - Hull above water: 14 tons
      - On freeboard deck: 18 tons
      - Above deck: 2 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     292 lbs / 132 Kg = 13.1 x 3.5 " / 90 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.58
   Metacentric height 1.6 ft / 0.5 m
   Roll period: 9.4 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.13
   Seaboat quality  (Average = 1.00): 1.00

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.384 / 0.399
   Length to Beam Ratio: 11.03 : 1
   'Natural speed' for length: 17.75 kts
   Power going to wave formation at top speed: 62 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 0.00 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 %,  14.60 ft / 4.45 m,  12.30 ft / 3.75 m
      - Forward deck:   35.00 %,  12.30 ft / 3.75 m,  9.51 ft / 2.90 m
      - Aft deck:   30.00 %,  9.51 ft / 2.90 m,  9.51 ft / 2.90 m
      - Quarter deck:   15.00 %,  9.51 ft / 2.90 m,  9.51 ft / 2.90 m
      - Average freeboard:      10.74 ft / 3.27 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 170.6 %
      - Above water (accommodation/working, high = better): 114.9 %
   Waterplane Area: 5,172 Square feet or 480 Square metres
   Displacement factor (Displacement / loading): 69 %
   Structure weight / hull surface area: 25 lbs/sq ft or 124 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.04
      - Overall: 0.54
   Cramped machinery, storage, compartmentation space
   Adequate accommodation and workspace room

[Jefgte]

And then the Coastal Destroyer concept...which I'm not happy with.
I've managed a 600tonner by severely restricting the armanent and performance.

This is a 800tonner that manages all the things I want,
but I am aware it's slightly larger than most of my existing DDs....

IMO, downgraded the old 499t Spear class DDs. They are 15 years old and can no longer be "serious" vs 1000t-1500t Fleet DDs. They will be fine as Coast Torpedo boats for another 8-10years.
Use your BP to build 1500t Fleet DDs.
;)
(In a few years downgraded 750t DDs...)

[Kaiser Kirk]

IMO, downgraded the old 499t Spear class DDs. They are 15 years old and can no longer be "serious" vs 1000t-1500t Fleet DDs. They will be fine as Coast Torpedo boats for another 8-10years.
Use your BP to build 1500t Fleet DDs.
;)
(In a few years downgraded 750t DDs...)

I think you are likely correct.
Covert my older Destroyers with no ASW/AA to Torpedo Boats as I build the new 'Fleet Destroyers'.

[Jefgte]

...Covert my older Destroyers with no ASW/AA to Torpedo Boats as I build the new 'Fleet Destroyers'.

Byzance had in 1918:
87 Torpedo Boats from 400t to 600t - 2630nm to 3500nm.
55 Fleet Destroyers from 750t (23) to 1000t - 1140t (32)- 3600nm to 6500nm.
After I ''ll built the new 1500t class, 750t DDs "ll be downgraded to Torpedo Boats.
-----------------
Parthians had in 1918:
48 (?) Torpedo Boats from 210t (32) to 499t (16) - 2050nm to 2650nm.
80 (?) Fleet Destroyers from 749t (68) to 1000t (12) - 3600nm to 5300nm.

[Kaiser Kirk]

Only the 32 Javilen class do they consider torpedo boats.
The old Spear and Atlatl classes were the first ASW conversions in 1916 to take advantage of the new hydrophones and give the Parthians an idea of what could be done.

Now that they've had a couple years experience, they can design a new vessel to meet the actual needs.

So moving the Spear and Atlatls to coastal service does look attractive.

Thanks. 

[Desertfox]

If you want coastal boats you have to sacrifice speed. Speed is very expensive especially the smaller you get. Look at the Japanese Kawakaze class for why I found could be done for cheap coastal work. Also get rid of the heavy AA gun, it's useless in a ship this small and takes up valuable tonnage. How is the misc weight split up btw?

[Kaiser Kirk]

If you want coastal boats you have to sacrifice speed. Speed is very expensive especially the smaller you get. Look at the Japanese Kawakaze class for why I found could be done for cheap coastal work. Also get rid of the heavy AA gun, it's useless in a ship this small and takes up valuable tonnage. How is the misc weight split up btw?

This was an attempt at vessel able to be more than just a torpedo boat, I wanted it to do the destroyer roles as well.
So there's tonnage for 6x21" and fire control, but also 1t for Air conditioning, and then paravanes, basic hydrophones, depth charges, & asw kite.

As for the AA, it's either 90mm or nothing right now. I've been thinking that in service the crews would complain about 90mm 10kg shells for one set of guns, and 90mm 11kg shells for the AA.

I have a design for a slower, less capable ship, at 600 tons.
But it is slower and more limited, with no expansion room.



Sea Hornet, Parthian Coastal Destroyer laid down 1919

Displacement:
   599 t light; 624 t standard; 688 t normal; 739 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (282.92 ft / 278.87 ft) x 27.89 ft x (7.94 / 8.32 ft)
   (86.23 m / 85.00 m) x 8.50 m  x (2.42 / 2.54 m)

Armament:
      3 - 3.54" / 90.0 mm 45.0 cal guns - 22.05lbs / 10.00kg shells, 200 per gun
     Quick firing guns in deck mounts, 1919 Model
     3 x Single mounts on centreline ends, majority forward
      2 raised mounts - superfiring
      1 - 3.54" / 90.0 mm 50.0 cal gun - 24.25lbs / 11.00kg shells, 250 per gun
     Anti-air gun in deck mount, 1919 Model
     1 x Single mount on sides, forward deck aft
      1 raised mount
      Weight of broadside 90 lbs / 41 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.24" / 6 mm         -               -
   2nd:   0.24" / 6 mm         -               -

Machinery:
   Coal and oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 15,235 shp / 11,365 Kw = 29.50 kts
   Range 2,300nm at 14.00 kts
   Bunker at max displacement = 116 tons (23% coal)

Complement:
   66 - 87

Cost:
   £0.162 million / $0.647 million

Distribution of weights at normal displacement:
   Armament: 17 tons, 2.5 %
      - Guns: 17 tons, 2.5 %
   Armour: 2 tons, 0.3 %
      - Armament: 2 tons, 0.3 %
   Machinery: 347 tons, 50.4 %
   Hull, fittings & equipment: 204 tons, 29.6 %
   Fuel, ammunition & stores: 89 tons, 12.9 %
   Miscellaneous weights: 30 tons, 4.3 %
      - Hull below water: 5 tons
      - Hull void weights: 1 tons
      - Hull above water: 1 tons
      - On freeboard deck: 21 tons
      - Above deck: 2 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     245 lbs / 111 Kg = 11.0 x 3.5 " / 90 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.40
   Metacentric height 1.3 ft / 0.4 m
   Roll period: 10.2 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.18
   Seaboat quality  (Average = 1.00): 1.00

Hull form characteristics:
   Hull has a flush deck,
     a ram bow and a round stern
   Block coefficient (normal/deep): 0.390 / 0.400
   Length to Beam Ratio: 10.00 : 1
   'Natural speed' for length: 16.70 kts
   Power going to wave formation at top speed: 65 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 15.00 degrees
   Stern overhang: -3.28 ft / -1.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  15.09 ft / 4.60 m,  12.47 ft / 3.80 m
      - Forward deck:   30.00 %,  12.47 ft / 3.80 m,  10.50 ft / 3.20 m
      - Aft deck:   35.00 %,  10.50 ft / 3.20 m,  10.50 ft / 3.20 m
      - Quarter deck:   15.00 %,  10.50 ft / 3.20 m,  10.50 ft / 3.20 m
      - Average freeboard:      11.40 ft / 3.47 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 171.1 %
      - Above water (accommodation/working, high = better): 150.3 %
   Waterplane Area: 4,755 Square feet or 442 Square metres
   Displacement factor (Displacement / loading): 58 %
   Structure weight / hull surface area: 25 lbs/sq ft or 122 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.61
      - Overall: 0.56
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room

Intended as a Coastal Destroyer,
operating out of Naval bases on local patrols and interdiction.

Guns are A(B)    TT(Q-AA)TT    (X) DC
The Q gun is on the top of the TDC tower, bracketed
by the two triple tubes.

The X gun is superimposed to be clear of the fan tail.

The choice of mixing 10kg 90mm rounds and 11kg AA 90mm rounds will prove a poor one.

To allow operations if cut off from oil supplies, coal (or wood) power is provided for 1/4 of the boilers, normally sprayed with oil. (25% * 90%=23)

For this, they need to be able to dash out at a high
cruise speed, have reserve for a full power attack run, and return to base.

For that, a 24 hour run at 20 knots (35t), and a 1 hour run at 30knots (8t) is specified. This gives a total of 43t of fuel needed. This allows the run to be made on purely oil fuel.   Simple transit between bases is expected at 2200nm at 14kts, which takes 64t, but requires use of the mixed firing.

Misc Wt.
1t - Resv

1.5t - FC

18t - 2x T3  21" torpedoes
3t - Depth charges

5t - Basic Hydrophones

[Jefgte]

Machinery: 347 tons, 50.4 %

Reduce to 50% & increase Miscellaneous weights (reserve weights)

[Kaiser Kirk]

The tonnage commitment for sufficient Coastal Destroyers grows quite large.
I only have the same BP as the other players...less if you consider some have expanded.
But I built a nation that sprawls across the globe.

So I decided to go back to a Torpedo Boat idea and redesign it to serve as an MTB leader.
That way the MTBs are more effective, but I don't have to pay for full squadrons of 800t destroyers tied to bases.

These don't do the full destroyer mission, but give me something to consider.
They have a yet - undesigned - 57mm AA gun. Worse case it's a basic refit to add after designed.

These are given partial 'coal' firing to allow wood/coal/mercantile sources to be used when bases are cut off.
With a max trial speed of 32.35knots, they can make a respectable sprint run.

Pesh-Kabz, Parthian Torpedo Boat Leader laid down 1917 (Engine 1920)

Displacement:
   449 t light; 464 t standard; 532 t normal; 587 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (279.06 ft / 275.59 ft) x 22.97 ft x (7.55 / 8.07 ft)
   (85.06 m / 84.00 m) x 7.00 m  x (2.30 / 2.46 m)

Armament:
      2 - 3.54" / 90.0 mm 45.0 cal guns - 22.05lbs / 10.00kg shells, 120 per gun
     Quick firing guns in deck mounts, 1917 Model
     2 x Single mounts on centreline, forward evenly spread
      1 raised mount
      1 - 2.24" / 57.0 mm 57.0 cal gun - 6.06lbs / 2.75kg shells, 200 per gun
     Anti-air gun in deck mount, 1917 Model
     1 x Single mount on centreline, aft deck centre
      1 raised mount
      4 - 0.59" / 15.0 mm 70.0 cal guns - 0.11lbs / 0.05kg shells, 1,500 per gun
     Machine guns in deck mounts, 1899 Model
     2 x Twin mounts on sides forward
      2 double raised mounts
      Weight of broadside 51 lbs / 23 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.12" / 3 mm         -               -

Machinery:
   Coal and oil fired boilers, steam turbines,
   Direct drive, 1 shaft, 13,112 shp / 9,781 Kw = 29.75 kts  Trial Speed: 32.35
   Range 1,052nm at 21.00 kts
   Bunker at max displacement = 123 tons (23% coal)

Complement:
   55 - 72

Cost:
   £0.102 million / $0.410 million

Distribution of weights at normal displacement:
   Armament: 10 tons, 1.9 %
      - Guns: 10 tons, 1.9 %
   Armour: 1 tons, 0.1 %
      - Armament: 1 tons, 0.1 %
   Machinery: 271 tons, 50.9 %
   Hull, fittings & equipment: 139 tons, 26.1 %
   Fuel, ammunition & stores: 83 tons, 15.6 %
   Miscellaneous weights: 29 tons, 5.4 %
      - On freeboard deck: 28 tons
      - Above deck: 1 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     151 lbs / 68 Kg = 6.8 x 3.5 " / 90 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.31
   Metacentric height 0.9 ft / 0.3 m
   Roll period: 10.2 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.16
   Seaboat quality  (Average = 1.00): 0.86

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a round stern
   Block coefficient (normal/deep): 0.390 / 0.402
   Length to Beam Ratio: 12.00 : 1
   'Natural speed' for length: 16.60 kts
   Power going to wave formation at top speed: 63 %
   Trim (Max stability = 0, Max steadiness = 100): 57
   Bow angle (Positive = bow angles forward): 15.00 degrees
   Stern overhang: -3.28 ft / -1.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  12.96 ft / 3.95 m,  10.66 ft / 3.25 m
      - Forward deck:   21.00 %,  10.66 ft / 3.25 m,  8.04 ft / 2.45 m
      - Aft deck:   44.00 %,  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:      9.02 ft / 2.75 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 169.4 %
      - Above water (accommodation/working, high = better): 107.2 %
   Waterplane Area: 3,658 Square feet or 340 Square metres
   Displacement factor (Displacement / loading): 54 %
   Structure weight / hull surface area: 21 lbs/sq ft or 103 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.00
      - Overall: 0.54
   Cramped machinery, storage, compartmentation space
   Adequate accommodation and workspace room
   Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

Trial Speed 31.64

This is meant as a Parthian Torpedo Boat Leader.
This will serve as a dedicate lead vessel for MTBs,
providing the long range navigation and radio facilities they lack.
Expected to be lead 4-8 MTBs

Seakeeping is minimal, as they expect choose when they go to sea.

Power : 29.75kts @ 13,112shp  all max  Trial :
27.75kts : 9834shp : 75% oil-fired max  Trial :
26.75kts : 8,442shp : 64% oil fired
21kts      : 3278shp : 25% : 25% oil sprayed
21kts      : 3278shp : 25%  : 90% coal-oil sprayed 10%
10kts      : 256shp : 2% - either

Fuel : 123 tons
94.7t : Oil
28.3t : Oil-sprayed coal (10/90)

Range :
380nm, 14hrs at 26.75kts, oil fired.
780nm, 37hrs at 21kts, oil fired

1250nm @ 10knts : oil-sprayed coal.

10 t : Leader Facilities
8t : 2TT3 Torpedoes 21"
1t : FC : Range finders, Torpedo Direction Center.