WesWorld

RAM’s 1911 frigates are old and outdated, and can/should be replaced, and I have been toying with a couple approaches.

So I’m looking for comments as to what the best course of action is and what design flaws I’ve managed.

The first is to simply update/refit the existing frigates. At only 590 tons standard, this is tempting and fairly cheap. They are however fairly pure ASW assets.

The other approach is to make a capable escort which would be capable of annoying/injuring marauding light forces, as well as supplementing the fleet destroyers.
Two are presented – one has guns, the other armor.

Armor on such a light vessel, and in light amounts, is fairly odd- the reasoning is as follows- most guns under 6” were only outfitted with common shell and lacked any real AP ability. This should then provide substantial protection against larger enemy destroyers, and even against larger foes, force use of AP projectiles with their lower % bursting charge.

==========Rebuilt Frigates==========
FF1, Dutch Frigate- rebuilt laid down 1911 (Engine 1929)

Displacement:
573 t light; 592 t standard; 678 t normal; 747 t full load

Dimensions: Length overall / water x beam x draught
229.66 ft / 229.66 ft x 26.25 ft x 9.84 ft (normal load)
70.00 m / 70.00 m x 8.00 m x 3.00 m

Armament:
3 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1928 Model
Dual purpose guns in deck mounts
on centreline ends, majority forward, 1 raised mount
4 - 1.57" / 40.0 mm guns (2x2 guns), 1.94lbs / 0.88kg shells, 1928 Model
Anti-aircraft guns in deck mounts
on side, all amidships
4 - 0.52" / 13.2 mm guns in single mounts, 0.09lbs / 0.04kg shells, 1911 Model
Machine guns in deck mounts
on side ends, evenly spread, all raised mounts - superfiring
Weight of broadside 47 lbs / 21 kg
Shells per gun, main battery: 200
4 - 21.0" / 533.4 mm above water torpedoes

Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 11,917 shp / 8,890 Kw = 27.00 kts
Range 5,500nm at 12.00 kts
Bunker at max displacement = 155 tons

Complement:
66 - 86

Cost:
£0.065 million / $0.262 million

Distribution of weights at normal displacement:
Armament: 6 tons, 0.9 %
Machinery: 290 tons, 42.7 %
Hull, fittings & equipment: 167 tons, 24.6 %
Fuel, ammunition & stores: 105 tons, 15.6 %
Miscellaneous weights: 110 tons, 16.2 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
195 lbs / 89 Kg = 15.2 x 3.0 " / 75 mm shells or 0.2 torpedoes
Stability (Unstable if below 1.00): 1.14
Metacentric height 0.9 ft / 0.3 m
Roll period: 11.8 seconds
Steadiness - As gun platform (Average = 50 %): 61 %
- Recoil effect (Restricted arc if above 1.00): 0.10
Seaboat quality (Average = 1.00): 1.22

Hull form characteristics:
Hull has raised forecastle
Block coefficient: 0.400
Length to Beam Ratio: 8.75 : 1
'Natural speed' for length: 15.15 kts
Power going to wave formation at top speed: 68 %
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 (% = measuring location as a percentage of overall length):
- Stem: 19.69 ft / 6.00 m
- Forecastle (20 %): 19.69 ft / 6.00 m (10.60 ft / 3.23 m aft of break)
- Mid (50 %): 10.60 ft / 3.23 m
- Quarterdeck (15 %): 10.60 ft / 3.23 m
- Stern: 10.60 ft / 3.23 m
- Average freeboard: 12.41 ft / 3.78 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 162.5 %
- Above water (accommodation/working, high = better): 61.6 %
Waterplane Area: 3,710 Square feet or 345 Square metres
Displacement factor (Displacement / loading): 76 %
Structure weight / hull surface area: 21 lbs/sq ft or 101 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.44
- Longitudinal: 2.99
- Overall: 0.54
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is cramped
Good seaboat, rides out heavy weather easily

Replace the old steam turbines with marine diesels, convert freed boiler room space to a fuel tank. Raise the forecastle to provide better seakeeping. Replace the guns with newer models. Add 4x 21" TT.



Unarmored “Guns”
FF46, Dutch Kanonneerbooten laid down 1929

Displacement:
954 t light; 1,035 t standard; 1,256 t normal; 1,433 t full load

Dimensions: Length overall / water x beam x draught
264.99 ft / 252.62 ft x 36.09 ft x 11.48 ft (normal load)
80.77 m / 77.00 m x 11.00 m x 3.50 m

Armament:
8 - 4.92" / 125 mm guns (4x2 guns), 59.59lbs / 27.03kg shells, 1926 Model
Dual purpose guns in deck mounts with hoists
on centreline ends, evenly spread, 2 raised mounts - superfiring
8 - 1.57" / 40.0 mm guns (4x2 guns), 1.95lbs / 0.89kg shells, 1928 Model
Anti-aircraft guns in deck mounts
on side, all amidships
4 - 0.52" / 13.2 mm guns in single mounts, 0.07lbs / 0.03kg shells, 1928 Model
Machine guns in deck mounts
on side, evenly spread, all raised mounts
Weight of broadside 493 lbs / 223 kg
Shells per gun, main battery: 200

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.59" / 15 mm 0.20" / 5 mm 0.20" / 5 mm
2nd: 0.59" / 15 mm - -

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 6,116 shp / 4,562 Kw = 21.00 kts
Range 10,000nm at 12.00 kts
Bunker at max displacement = 399 tons

Complement:
105 - 137

Cost:
£0.446 million / $1.783 million

Distribution of weights at normal displacement:
Armament: 62 tons, 4.9 %
Armour: 10 tons, 0.8 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 10 tons, 0.8 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 188 tons, 15.0 %
Hull, fittings & equipment: 620 tons, 49.3 %
Fuel, ammunition & stores: 302 tons, 24.1 %
Miscellaneous weights: 75 tons, 6.0 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,807 lbs / 820 Kg = 30.3 x 4.9 " / 125 mm shells or 0.7 torpedoes
Stability (Unstable if below 1.00): 1.09
Metacentric height 1.3 ft / 0.4 m
Roll period: 13.5 seconds
Steadiness - As gun platform (Average = 50 %): 71 %
- Recoil effect (Restricted arc if above 1.00): 0.91
Seaboat quality (Average = 1.00): 1.31

Hull form characteristics:
Hull has raised forecastle
Block coefficient: 0.420
Length to Beam Ratio: 7.00 : 1
'Natural speed' for length: 15.89 kts
Power going to wave formation at top speed: 57 %
Trim (Max stability = 0, Max steadiness = 100): 54
Bow angle (Positive = bow angles forward): 18.00 degrees
Stern overhang: 6.56 ft / 2.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 17.85 ft / 5.44 m
- Forecastle (20 %): 16.37 ft / 4.99 m (14.57 ft / 4.44 m aft of break)
- Mid (50 %): 14.57 ft / 4.44 m
- Quarterdeck (15 %): 6.56 ft / 2.00 m
- Stern: 6.56 ft / 2.00 m
- Average freeboard: 12.44 ft / 3.79 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 94.3 %
- Above water (accommodation/working, high = better): 128.0 %
Waterplane Area: 5,684 Square feet or 528 Square metres
Displacement factor (Displacement / loading): 132 %
Structure weight / hull surface area: 66 lbs/sq ft or 323 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.87
- Longitudinal: 3.44
- Overall: 1.00
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent
Ship has slow, easy roll, a good, steady gun platform
Good seaboat, rides out heavy weather easily

The stern is cut down to serve as a depth charge/mine deck.

One concern would be as the speed comes up, would the stern get buried ?



“Armored”

FF46 Evertsen, Dutch Kanonneerbooten laid down 1929

Displacement:
986 t light; 1,035 t standard; 1,256 t normal; 1,433 t full load

Dimensions: Length overall / water x beam x draught
264.99 ft / 252.62 ft x 36.09 ft x 11.48 ft (normal load)
80.77 m / 77.00 m x 11.00 m x 3.50 m

Armament:
6 - 3.94" / 100 mm guns (3x2 guns), 30.51lbs / 13.84kg shells, 1926 Model
Dual purpose guns in deck mounts with hoists
on centreline ends, majority forward, 2 raised mounts - superfiring
8 - 1.57" / 40.0 mm guns (4x2 guns), 1.95lbs / 0.88kg shells, 1928 Model
Anti-aircraft guns in deck mounts
on side, all amidships
4 - 0.52" / 13.2 mm guns in single mounts, 0.07lbs / 0.03kg shells, 1928 Model
Machine guns in deck mounts
on side, evenly spread, all raised mounts
Weight of broadside 199 lbs / 90 kg
Shells per gun, main battery: 200

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 1.18" / 30 mm 196.85 ft / 60.00 m 9.84 ft / 3.00 m
Ends: Unarmoured
Main Belt covers 120 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.18" / 30 mm 0.79" / 20 mm 0.79" / 20 mm
2nd: 0.59" / 15 mm - -

- Armour deck: 0.79" / 20 mm, Conning tower: 1.18" / 30 mm

Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 6,116 shp / 4,562 Kw = 21.00 kts
Range 10,000nm at 12.00 kts
Bunker at max displacement = 399 tons

Complement:
105 - 137

Cost:
£0.327 million / $1.307 million

Distribution of weights at normal displacement:
Armament: 25 tons, 2.0 %
Armour: 195 tons, 15.6 %
- Belts: 94 tons, 7.5 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 16 tons, 1.3 %
- Armour Deck: 83 tons, 6.6 %
- Conning Tower: 3 tons, 0.2 %
Machinery: 188 tons, 15.0 %
Hull, fittings & equipment: 518 tons, 41.3 %
Fuel, ammunition & stores: 270 tons, 21.5 %
Miscellaneous weights: 60 tons, 4.8 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
2,523 lbs / 1,144 Kg = 82.7 x 3.9 " / 100 mm shells or 1.1 torpedoes
Stability (Unstable if below 1.00): 1.18
Metacentric height 1.5 ft / 0.4 m
Roll period: 12.5 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.34
Seaboat quality (Average = 1.00): 1.40

Hull form characteristics:
Hull has raised forecastle
Block coefficient: 0.420
Length to Beam Ratio: 7.00 : 1
'Natural speed' for length: 15.89 kts
Power going to wave formation at top speed: 57 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 18.00 degrees
Stern overhang: 6.56 ft / 2.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 17.85 ft / 5.44 m
- Forecastle (20 %): 16.37 ft / 4.99 m (14.57 ft / 4.44 m aft of break)
- Mid (50 %): 14.57 ft / 4.44 m
- Quarterdeck (15 %): 6.56 ft / 2.00 m
- Stern: 6.56 ft / 2.00 m
- Average freeboard: 12.44 ft / 3.79 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 70.4 %
- Above water (accommodation/working, high = better): 128.0 %
Waterplane Area: 5,684 Square feet or 528 Square metres
Displacement factor (Displacement / loading): 151 %
Structure weight / hull surface area: 55 lbs/sq ft or 271 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.88
- Longitudinal: 3.08
- Overall: 1.00
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is excellent
Ship has slow, easy roll, a good, steady gun platform
Good seaboat, rides out heavy weather easily

"Y" turret is superimposed over the cut-down fantail, which serves as the depth charge (or mine) deck.

8x125mm on 1,000 tons!!! Holy cow!!! And I thought my 10x120mm 2,000 ton ship was a bit crazy.

I say go with 4x125mm, some deck armor, and a tad more speed.

Hmm, an adverse reaction...

Perfectly reasonable,
But bear with me, I may not in fact be insane, I may just be lacking coffee.... but I can fix that.

So, if I go with 4 single 125mm, 2 superimposed, that would be reasonable?

However... the twin 125mm only take up marginally more deck space than singles.

I would say length is my real demon, Mahan had 4 singles on 334', but also 12xTT taking up ~42'+ whereas I don't have any torpedo tubes demanding deck space, and below decks I have far less machinery eating up space. I have the same beam, depending on the book I have more draft, and my hull is in no way stressed. This sound like a reasonable case for 4x2 125mm? Or am I just way out?

Armor....I was saving the deck armor for exploring the "armor" version. I kinda like that version. RAM liked armor too.

Speed : This is the one I had difficulty with. What am I going to catch or evade at 24 knts that I can't at 21knts?
Fastest submarines of the day OTL didn't get faster until the late 1920s, and any sub will presumably submerge for a slower pace anyhow.

I thought about upping the cruising spd to match the fleet, I can see merit there.

Thanks for the comments
-Kaiser Kirk

If there´s no other heavy gear on her deck 4x2 might be possible, methinks.

Probably a drawing might help...?!

Quoted

If there´s no other heavy gear on her deck 4x2 might be possible, methinks.

Messing around a bit with my 130 mm twin turrets and the FF46 dimensions, I think it will fit, but I doubt it would win any prizes for beauty. Rough guess gives you 18 meters for the superstucture+funnel between the forward pair and the aft pair of 125mm turrets. Not much but will probably be enough for fairly simple stuff.

Will there also be enough space for boats and the like?

Boats? Boats?!? We don't need no stinkin' Boats!!
:-)
(Hell, in a gun fight they'll be blasted to tiny wooden bits anyway... with 'A Few Good Hits')
...
...
...
I think that if you make the supersturcture narrow enough, there will be some space along the sides. But the test I did was fairly rough and simple. One would have to make an actual picture to make sure of it.

I can certainlyextend the hull a little bit.... There (see below). Now she's 295' which means the difference between her and Mahan can be explained by the 42' TT lengths (Mahan had 3 sets, 1 centerline trained fore/aft, two further aft adjacent to each other, also trained fore/aft)

-Pictures....not in my skill set. Best I could do right now is photocopy (maybe scan& print) a destroyer deck plan from my Jane's ships of WW2 , cut out the Torps, glue it together and paste it on my computer screen. However I have the sneaking suspicion that would fail to convey the desired information, and I don't think glue will agree with the screen.

Other issues: these are escorts, intended to fall under the G(I)(1) and G(I)(2) categories,
-Therefore max speed is 24kts.
-So, by the design rules for Gentlemen, they do not qualify as light fast combatents by my reading
-so Comp hull minimum is 1.0 ?

However, if we're good on hull dimensions...concept ?
Most DEs OTL were built to be the smallest that could do the job and churned out quickly in war conditions. Treaty limits mean I'd done on capital ships and am looking to build escorts in peacetime. So the first offering was a 'get the job done', the others are a 2nd class destroyer type idea.
Is 21 knots to slow for a DE in Wesworld?
Do my thoughts on light armor seem reasonable?
Would a cut down fantail like that bury itself at 21kts?
=========Revised F46==============
FF46, Dutch Kanonneerbooten laid down 1929

Displacement:
999 t light; 1,081 t standard; 1,307 t normal; 1,489 t full load

Dimensions: Length overall / water x beam x draught
308.00 ft / 295.28 ft x 32.81 ft x 10.66 ft (normal load)
93.88 m / 90.00 m x 10.00 m x 3.25 m

Armament:
8 - 4.92" / 125 mm guns (4x2 guns), 59.59lbs / 27.03kg shells, 1926 Model
Dual purpose guns in deck mounts with hoists
on centreline ends, evenly spread, 2 raised mounts - superfiring
Main guns limited to end-on fire
8 - 1.57" / 40.0 mm guns (4x2 guns), 1.95lbs / 0.88kg shells, 1928 Model
Anti-aircraft guns in deck mounts
on side, all amidships
4 - 0.52" / 13.2 mm guns in single mounts, 0.07lbs / 0.03kg shells, 1928 Model
Machine guns in deck mounts
on side, evenly spread, all raised mounts
Weight of broadside 493 lbs / 223 kg
Shells per gun, main battery: 200

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.59" / 15 mm 0.20" / 5 mm 0.20" / 5 mm
2nd: 0.59" / 15 mm - -

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 5,786 shp / 4,317 Kw = 21.00 kts
Range 10,000nm at 12.00 kts
Bunker at max displacement = 408 tons

Complement:
108 - 141

Cost:
£0.446 million / $1.785 million

Distribution of weights at normal displacement:
Armament: 62 tons, 4.7 %
Armour: 10 tons, 0.8 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 10 tons, 0.8 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 178 tons, 13.6 %
Hull, fittings & equipment: 674 tons, 51.6 %
Fuel, ammunition & stores: 309 tons, 23.6 %
Miscellaneous weights: 75 tons, 5.7 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
2,089 lbs / 947 Kg = 35.1 x 4.9 " / 125 mm shells or 0.8 torpedoes
Stability (Unstable if below 1.00): 1.13
Metacentric height 1.2 ft / 0.4 m
Roll period: 12.7 seconds
Steadiness - As gun platform (Average = 50 %): 71 %
- Recoil effect (Restricted arc if above 1.00): 1.15
Seaboat quality (Average = 1.00): 1.74

Hull form characteristics:
Hull has raised forecastle
Block coefficient: 0.443
Length to Beam Ratio: 9.00 : 1
'Natural speed' for length: 17.18 kts
Power going to wave formation at top speed: 50 %
Trim (Max stability = 0, Max steadiness = 100): 41
Bow angle (Positive = bow angles forward): 18.00 degrees
Stern overhang: 6.56 ft / 2.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 18.96 ft / 5.78 m
- Forecastle (20 %): 16.96 ft / 5.17 m (14.57 ft / 4.44 m aft of break)
- Mid (50 %): 14.57 ft / 4.44 m
- Quarterdeck (15 %): 6.56 ft / 2.00 m
- Stern: 6.56 ft / 2.00 m
- Average freeboard: 12.60 ft / 3.84 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 88.2 %
- Above water (accommodation/working, high = better): 134.5 %
Waterplane Area: 6,145 Square feet or 571 Square metres
Displacement factor (Displacement / loading): 140 %
Structure weight / hull surface area: 62 lbs/sq ft or 303 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.89
- Longitudinal: 2.85
- Overall: 1.00
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent
Ship has slow, easy roll, a good, steady gun platform
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

The concept is generally good, though I do wonder about the deck space nonetheless.

It might be worth looking at the CDS tonnage used by the Netherlands and considering whether some torpedo-armed DEs are worthwhile. India has decided they are. Still, these pack quite a punch on their own.

I'm inclined to think that the fantail might be pretty wet on the open ocean or in crappy weather such as cyclone season.

Well you could go with only three mounts. As not many ships under 1,500 tons can match even 6x5". Not even some 2,000+ DLs can match that firepower.
I would say some extra speed could be useful, as you can use it as extra escorts for your battleline.

Quoted

Other issues: these are escorts, intended to fall under the G(I)(1) and G(I)(2) categories,
-Therefore max speed is 24kts.
-So, by the design rules for Gentlemen, they do not qualify as light fast combatents by my reading
-so Comp hull minimum is 1.0 ?

... Unless you take the South African approach when it comes to the 24 knot speed limit.

Well when it was all crunched out, the escorts didn’t fit in 1929 unless I started them in Q4. Rooijen indicates that the 8x125mm vessel is a tight fit, which fits with my simple scaling off Jane’s. Though I did notice that my fiddling with beam had driven recoil over 1. , but that was easily fixable.

I did explore Desert Fox’s 24knots, and that would be doable on that hull if I dropped the guns to 8x100mm. Alternately I could balloon the hull and do 8x125mm & 24knts. I may do that later with an 1,800ton design combining the 24kts, the guns and the armor.

However, I’m trying to explore viable convoy escort platforms in the 1000 ton range.
Seems like at 1000 tons I can have 24kts, guns or armor. At 1300 I can have two, and at 1800 I get all three 

I also started looking at the quicker / lighter escorts and came up with a mighty mite <600t. I am concerned that SS is simply allowing me to cram to much on a tiny hull. On the other hand my basis for comparison are WWII frigates, which normally had token AS armament. Looking at a Castle class, replacing the squid and 4” with the twin 100mm would ‘fit’. The two vessels are the same length, I simply took the beam down, though I am using M.A.N. diesels rather than triple expansion, which allows a smaller plant.. Perhaps twin 75mm mounts would be more reasonable, and I should probably drop the 20mm back o 13.2mm…

As a note- the 77mm length is just the starting point I’m using, based on a note about the Castle class to the effect that the Flowers were to small to fit the North Atlantic wave distance

FF46, Netherlands Sloop laid down 1930

Displacement:
598 t light; 629 t standard; 760 t normal; 865 t full load

Dimensions: Length overall / water x beam x draught
266.34 ft / 252.62 ft x 25.26 ft x 9.02 ft (normal load)
81.18 m / 77.00 m x 7.70 m x 2.75 m

Armament:
4 - 3.94" / 100 mm guns (2x2 guns), 30.51lbs / 13.84kg shells, 1930 Model
Dual purpose guns in deck mounts with hoists
on centreline, all forward, 1 raised mount - superfiring
4 - 1.57" / 40.0 mm guns (1x4 guns), 1.95lbs / 0.88kg shells, 1930 Model
Anti-aircraft guns in deck mount
on centreline amidships
8 - 0.79" / 20.0 mm guns (4x2 guns), 0.24lbs / 0.11kg shells, 1930 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, 2 raised mounts
Weight of broadside 132 lbs / 60 kg
Shells per gun, main battery: 200

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.98" / 25 mm 0.79" / 20 mm 0.59" / 15 mm
2nd: 0.59" / 15 mm - -

- Conning tower: 0.79" / 20 mm

Machinery:
Diesel Internal combustion motors,
Geared drive, 1 shaft, 4,370 shp / 3,260 Kw = 21.00 kts
Range 8,000nm at 12.00 kts
Bunker at max displacement = 236 tons

Complement:
72 - 94

Cost:
£0.223 million / $0.892 million

Distribution of weights at normal displacement:
Armament: 16 tons, 2.2 %
Armour: 11 tons, 1.4 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 9 tons, 1.2 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 1 tons, 0.2 %
Machinery: 132 tons, 17.4 %
Hull, fittings & equipment: 349 tons, 45.9 %
Fuel, ammunition & stores: 162 tons, 21.3 %
Miscellaneous weights: 90 tons, 11.8 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,074 lbs / 487 Kg = 35.2 x 3.9 " / 100 mm shells or 0.6 torpedoes
Stability (Unstable if below 1.00): 1.01
Metacentric height 0.6 ft / 0.2 m
Roll period: 13.2 seconds
Steadiness - As gun platform (Average = 50 %): 87 %
- Recoil effect (Restricted arc if above 1.00): 0.81
Seaboat quality (Average = 1.00): 1.75

Hull form characteristics:
Hull has raised forecastle
Block coefficient: 0.462
Length to Beam Ratio: 10.00 : 1
'Natural speed' for length: 15.89 kts
Power going to wave formation at top speed: 53 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 22.00 degrees
Stern overhang: 6.56 ft / 2.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 17.72 ft / 5.40 m
- Forecastle (20 %): 14.44 ft / 4.40 m (9.84 ft / 3.00 m aft of break)
- Mid (50 %): 9.84 ft / 3.00 m
- Quarterdeck (15 %): 9.84 ft / 3.00 m
- Stern: 9.84 ft / 3.00 m
- Average freeboard: 11.02 ft / 3.36 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 87.3 %
- Above water (accommodation/working, high = better): 102.2 %
Waterplane Area: 3,926 Square feet or 365 Square metres
Displacement factor (Displacement / loading): 153 %
Structure weight / hull surface area: 43 lbs/sq ft or 211 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.90
- Longitudinal: 3.19
- Overall: 1.02
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is adequate
Ship has slow, easy roll, a good, steady gun platform
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

Bigger is better. The Flower class were proven to be too small. The Rivers and Lochs were better suited to open ocean work.

8x125mm guns is overkill on such a small vessel considering her role. A single or Duple mount forwards is all that is required, leaving loads of space for accomodation, racks of depth charges, boats and other goodies.

The issue, really, on the amount and type of main guns is what's your expectation of the air threat where these ships would operate. If you're in a low-air threat environment, a single or twin 125mm will do nicely for punching holes in a surfaced submarine. If there is more of an air threat, 4 100mm's might be better.

Aerial Threat: with these smaller escort vessels, I was expecting they'd mainly escort convoys in wartime. Given the location of India's Diego Garcia, the main aerial foe expected would be a number of long range naval reconn / bombers. - larger, slower airplanes. The secondary threat would be seaplane from tenders. When India attacks again, aerial threats are also expected to operate out of the Andaman islands to savage coastal trade in NW DEI.

Surface threat: Fast moving surface raiders such as India's T-19 class of recent years. They are tiny bit little larger (1 ton standard, 9m longer, -0.5m beam), a lot faster, and carry 2x105mm and 4 TT instead of 4x100mm.
These could savage the same transport routes as the planes, though with a longer range.

I presume the T-19s are officially an "unlimited" 600ts, not 630 ...which happens to be 105%...

ASW threat : Subs and stuff. The classic escort role.


Optimally, I'd like to shrink the vessel under 500 tons light, to save 5 months build time, but that seems...difficult.

=========500 tons, 75mm guns==============
FF46, Netherlands Sloop laid down 1930

Displacement:
500 t light; 520 t standard; 647 t normal; 747 t full load

Dimensions: Length overall / water x beam x draught
266.34 ft / 252.62 ft x 25.26 ft x 9.02 ft (normal load)
81.18 m / 77.00 m x 7.70 m x 2.75 m

Armament:
4 - 2.95" / 75.0 mm guns (2x2 guns), 12.87lbs / 5.84kg shells, 1930 Model
Dual purpose guns in deck mounts with hoists
on centreline, all forward, 1 raised mount - superfiring
4 - 1.57" / 40.0 mm guns (1x4 guns), 1.95lbs / 0.88kg shells, 1930 Model
Anti-aircraft guns in deck mount
on centreline amidships
4 - 0.79" / 20.0 mm guns in single mounts, 0.24lbs / 0.11kg shells, 1930 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, all raised mounts
Weight of broadside 60 lbs / 27 kg
Shells per gun, main battery: 200

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.98" / 25 mm 0.59" / 15 mm 0.79" / 20 mm
2nd: 0.59" / 15 mm - -

- Conning tower: 0.79" / 20 mm

Machinery:
Diesel Internal combustion motors,
Geared drive, 1 shaft, 4,611 shp / 3,440 Kw = 22.00 kts
Range 8,500nm at 12.00 kts
Bunker at max displacement = 227 tons

Complement:
63 - 83

Cost:
£0.181 million / $0.726 million

Distribution of weights at normal displacement:
Armament: 8 tons, 1.2 %
Armour: 7 tons, 1.1 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 6 tons, 0.9 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 1 tons, 0.2 %
Machinery: 140 tons, 21.6 %
Hull, fittings & equipment: 296 tons, 45.8 %
Fuel, ammunition & stores: 146 tons, 22.6 %
Miscellaneous weights: 50 tons, 7.7 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,010 lbs / 458 Kg = 78.5 x 3.0 " / 75 mm shells or 0.6 torpedoes
Stability (Unstable if below 1.00): 1.17
Metacentric height 0.9 ft / 0.3 m
Roll period: 11.5 seconds
Steadiness - As gun platform (Average = 50 %): 72 %
- Recoil effect (Restricted arc if above 1.00): 0.28
Seaboat quality (Average = 1.00): 1.75

Hull form characteristics:
Hull has raised forecastle
Block coefficient: 0.393
Length to Beam Ratio: 10.00 : 1
'Natural speed' for length: 15.89 kts
Power going to wave formation at top speed: 53 %
Trim (Max stability = 0, Max steadiness = 100): 41
Bow angle (Positive = bow angles forward): 22.00 degrees
Stern overhang: 6.56 ft / 2.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 17.72 ft / 5.40 m
- Forecastle (20 %): 13.62 ft / 4.15 m (9.51 ft / 2.90 m aft of break)
- Mid (50 %): 9.51 ft / 2.90 m
- Quarterdeck (15 %): 9.51 ft / 2.90 m
- Stern: 9.51 ft / 2.90 m
- Average freeboard: 10.66 ft / 3.25 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 88.5 %
- Above water (accommodation/working, high = better): 106.4 %
Waterplane Area: 3,698 Square feet or 344 Square metres
Displacement factor (Displacement / loading): 163 %
Structure weight / hull surface area: 39 lbs/sq ft or 191 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.90
- Longitudinal: 3.00
- Overall: 1.01
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is adequate
Ship has slow, easy roll, a good, steady gun platform
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

And that aerial threat is bolstered by the likely addition of further aircraft carriers to the Indian OOB. Running the Chagos/Lakshadweep/Ceylon gauntlet could be trying for Dutch convoys.

You'll note that India has only built the one T-19 torpedo-boat. I'm still not certain whether these are good choices for India, so I'm building other stuff in the meantime. Still, the potential is there.

Yes, T-19 is officially 600 t.

You can put together a cheap coastal escort on 500 t, but that's what it will be, and you won't enjoy much of an anti-surface punch on it.

At this time, the Naval staff presumes that the Indian carriers will be preoccupied with (loosing to) the Netherlands navy. It may not be a good presumption...

I was using the T-19 as an example, given the ship building capabilities of many of the SATSUMA members, small fast craft seem a likely foe. With the many islands and extensive intra-DEI trade, raiders such as the T-19 style craft could be a considerable headache.

You are quite correct, I am finding the 500-ton level difficult to generate an adequate ship and keep speed at 17kts+4 (i.e. fastest surfaced Dutch sub+4kts). I'd really like 125mm for anti MTB work but could only mount 2, so the 4x100mm looks better. The 75mm just is a bit small. All work adequately on the larger long-range aircraft I would be expecting.

Bigger = Better

Cheers,

PS. Think Black Swan size.

Its a really bad idea to use 600ton vessels to escort convoys through actual oceans. The 1000ton Flowers were proven to be too small.

Go for 1500tons, a speed of about 20knts. 2x100mm HA guns and lots of depth charge projectors.

600 tons is really kind of small for oceanic escort work. It's workable for coastal jobs, along the Dutch or DEI coasts, but out in the open Indian Ocean it's likely to be a bit too small. Take a look at the planned German R-11 minesweeper/escort for such a small vessel, but I wouldn't plan on using such a ship in the Atlantic.