WesWorld

Dutch Escorts

The Dutch have long maintained purpose built escorts. Of the 80+ on hand, the 45-strong Frigate class 500 ton vessels are aging, and while refurbished once and spend most of their time in reserve.. will be due for the breakers ~1945 or so.
22 of the S19 class was built under the Cleito treaty as exempt vessels. In 1938, 4 improved versions, the S44 class, were built with the idea that the design could be tested, and then when the Capital ships were completed, produced en masse in the 1940s.

Parameters

Tonnage:
As small as possible.
At least <1,500 tons, preferably ~750tons.

Weaponry :
With Phillips Electronics, the Dutch were, OTL, ahead of the game in Radar and fire control in general. In early 1940, when Holland fell, radar-guided search lights were entering service, the early decimetric radar brought to England was in advance of the Brits own, and hastily exported Phillips tubes went into British Radars, etc. So I figure about 1 year behind the Americans. Prox fuses hit the South Pacific in May, 1942, so 1940 is when the Dutch prox fuses entered service. Early prox fuses needed specialty small vaccumn tubes, and 5" was about the smallest shell which could fit them. So the Dutch 125mm can be forecast as the main AA barrage gun. For mid range, they use 40mm guns in stacked Quad 'wirblewind' style mounts with Hazemeyer gyrostabilization gear, and are working on RPC in conjunction with the SAE. For close in defense they use the single or twin 23mm FN-Madsen.


a 1(TT) b
So... Desired weaponry A / B Q X / Y
c (TT)2 d


bah, spaces don't format right. "a" is behind and outside of B, "1" before and outside of "Q", "b" before and outside of "X" etc, with "2" aft and outside of "Q"

With A & Y being twin 125mm mount & hoist
With B & X being quad 40mm Hazemeyer mounts
With Q being the Searchlight/Torpedo Control Director tower
and
1 & 2 are Quad 40mm Hazemeyer mounts on a raised platform around the TCD 'en echelon' , with the triple tubes under the platforms
a,b,c,d are raised platforms for 2 single 23mm mounts each.

note : the wieght of the Hazemeyer gear is simmed as "other" armor on the mount - 21mm for Quads, 11mm for Twins. That puts the weight in the right place.

Ranges:
Dutch Capital ships are built for the "worst case" - the need to make an unrefueled run at 15knts from the Netherlands, around the UK, around Cape Horn to Jakarta. That's 16,500nm. Cruisers and Heavy Destroyers (Z77/Z81) are being built for the Netherlands-Kongo-DEI run. I'd like these new sloops to be able to make the Matadi, Kongo to Batavia, Java run... about 7,200nm, with a 20% reserve makes 8,650nm. Cruise speed only needs to be about 12kts, which gives freedom to move around the convoy.

Speed :
Desired top speed is 25-26kts. The Dutch should know the IJN subs are fast by now, but not know what their real top speed is, so there's no real OPFOR there, but with the Ijelsijk class small BBs at 23kts, the idea was they could be a core of a slow squadron of older BBs to counter the Bahrat fleet/serve as heavy convoy escorts/group with the older/slower BBs in a slow Squadron... at 25-26kts, the sloops can- barely- work with them in a pinch. Not desirable to do, but useful as an option.

Hull form & Seakeeping :
Over in Navalism it's been observed that DD freeboards were far less than we sim. Basically, DDs had "poor" seakeeping- they are small and have to slow down in high seas. Now on my Z77/Z81 heavy DDs, I went for good seakeeping anyhow- they are for midocean trips in any weather. Considering most of the life of these sloops is to escort convoys at lower speeds, 0.75+ seakeeping is acceptable. Shorter L:B is better for turning radius, which in turn is better for subhunting or dodging aerial torpedoes. A fairly beamy ship will be needed to host the twin mounts.

Result :
Well, the seakeeping is a bit higher than desired. Armor was added as an anti-strafing measure ala the Fletcher class. Size is ~100 tons more than desired. Would prefer 26kts. At 19% fuel percentage is about maxed. With 0.5 comp hull required, the 0.62 represents a 20% reserve, more than adequate for a strong hull. Aft is cut down, and is the depth-charge platform.

I can drop the armor and add a knot, making her 26kts and 0.91seakeeping and 0.75 comp hull, but in hindsight I kinda like the armor, and the South-Atlantic/South Indian ocean route can have rough seas. Plus the additional engine space turns below decks from Adequate to Cramped, I want Adequate for the long trip.

So.... what could I do to meet those parameters with a smaller ship? Do I actually need the various things I think I need? Smaller could be far cheaper- but would that be as suited to open-ocean work? The Dutch view these as 2nd tier combatants, not minimal vessels - more the USN Evart's class than the RN's Flower class.

Ideas/Comments/Competing designs?

S52, Netherlands Escort laid down 1941

Displacement:
1,099 t light; 1,175 t standard; 1,356 t normal; 1,501 t full load

Dimensions: Length overall / water x beam x draught
303.87 ft / 298.56 ft x 42.65 ft x 9.32 ft (normal load)
92.62 m / 91.00 m x 13.00 m x 2.84 m

Armament:
4 - 4.92" / 125 mm guns (2x2 guns), 59.52lbs / 27.00kg shells, 1926 Model
Dual purpose guns in deck mounts with hoists
on centreline ends, evenly spread
8 - 1.57" / 40.0 mm guns (2x4 guns), 1.94lbs / 0.88kg shells, 1936 Model
Anti-aircraft guns in deck mounts with hoists
on centreline ends, evenly spread, all raised mounts
8 - 1.57" / 40.0 mm guns (2x4 guns), 1.94lbs / 0.88kg shells, 1936 Model
Anti-aircraft guns in deck mounts
on side, all amidships, all raised mounts - superfiring
8 - 0.91" / 23.0 mm guns in single mounts, 0.37lbs / 0.17kg shells, 1926 Model
Breech loading guns in deck mounts
on side ends, evenly spread
Weight of broadside 272 lbs / 123 kg
Shells per gun, main battery: 300
6 - 21.0" / 533.4 mm above water torpedoes

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 0.98" / 25 mm 229.66 ft / 70.00 m 8.01 ft / 2.44 m
Ends: Unarmoured
Main Belt covers 118 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.98" / 25 mm 0.20" / 5 mm 0.20" / 5 mm
2nd: 0.39" / 10 mm 0.83" / 21 mm -
3rd: 0.39" / 10 mm 0.83" / 21 mm -
4th: 0.20" / 5 mm - -

- Armour deck: 0.59" / 15 mm, Conning tower: 0.98" / 25 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 12,073 shp / 9,006 Kw = 25.00 kts
Range 8,650nm at 12.00 kts
Bunker at max displacement = 326 tons

Complement:
111 - 145

Cost:
£0.691 million / $2.763 million

Distribution of weights at normal displacement:
Armament: 34 tons, 2.5 %
Armour: 175 tons, 12.9 %
- Belts: 74 tons, 5.5 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 13 tons, 1.0 %
- Armour Deck: 86 tons, 6.3 %
- Conning Tower: 3 tons, 0.2 %
Machinery: 319 tons, 23.5 %
Hull, fittings & equipment: 470 tons, 34.7 %
Fuel, ammunition & stores: 257 tons, 19.0 %
Miscellaneous weights: 100 tons, 7.4 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,468 lbs / 666 Kg = 24.6 x 4.9 " / 125 mm shells or 0.7 torpedoes
Stability (Unstable if below 1.00): 1.29
Metacentric height 2.2 ft / 0.7 m
Roll period: 12.1 seconds
Steadiness - As gun platform (Average = 50 %): 59 %
- Recoil effect (Restricted arc if above 1.00): 0.24
Seaboat quality (Average = 1.00): 1.04

Hull form characteristics:
Hull has low quarterdeck
Block coefficient: 0.400
Length to Beam Ratio: 7.00 : 1
'Natural speed' for length: 17.28 kts
Power going to wave formation at top speed: 60 %
Trim (Max stability = 0, Max steadiness = 100): 57
Bow angle (Positive = bow angles forward): 18.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 16.34 ft / 4.98 m
- Forecastle (20 %): 14.70 ft / 4.48 m
- Mid (50 %): 14.70 ft / 4.48 m
- Quarterdeck (15 %): 6.69 ft / 2.04 m (14.70 ft / 4.48 m before break)
- Stern: 6.69 ft / 2.04 m
- Average freeboard: 13.63 ft / 4.15 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 106.0 %
- Above water (accommodation/working, high = better): 133.5 %
Waterplane Area: 7,838 Square feet or 728 Square metres
Displacement factor (Displacement / loading): 114 %
Structure weight / hull surface area: 41 lbs/sq ft or 199 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.56
- Longitudinal: 1.62
- Overall: 0.62
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent

I appreciate you sharing the thoughts behind the design - and I suppose they are what I have the most concern about, rather than the individual facets of the design itself.

I am doubtful of the utility of the torpedo tubes on such a class of vessel, with the speed proposed. I think it unlikely that they could maneuver against an enemy to gain position to launch their torpedoes. I suppose that if the enemy task force was composed of Great War vintage battleships, these sloops might be successful, but even so the time under the guns of the enemy would make their survival questionable. I would consider recasting the design without the torpedo tubes.

Likewise, I think the speed is excessive. Sonar at this period suffers from significant drop off above 20 knots. Opting for less speed, rather than more, I think would pay dividends - and you could find in the design sufficient tonnage for a reasonable antisubmarine armament, unless that comprises the 100 tons miscellaneous weight already incorporated.

I *like* the heavy antiaircraft armament, particularly if it is matched with good fire control. Others may call it excessive.

I'd propose an altertive design without torpedo tubes and without so much speed. It also turns out to be a stronger design, per our rules.

--------------

Schichau Export Sloop Escort laid down 1941

Displacement: 1,102 t light; 1,175 t standard; 1,356 t normal; 1,501 t full load

Dimensions: Length overall / water x beam x draught

303.87 ft / 298.56 ft x 42.65 ft x 9.32 ft (normal load) [92.62 m / 91.00 m x 13.00 m x 2.84 m]

Armament:

4 - 4.92" / 125 mm guns (2x2 guns), 59.59lbs / 27.03kg shells, 1926 Model Dual purpose guns in deck mounts with hoists on centreline ends, evenly spread
8 - 1.57" / 40.0 mm guns (2x4 guns), 1.94lbs / 0.88kg shells, 1936 Model Anti-aircraft guns in deck mounts with hoists on centreline ends, evenly spread, all raised mounts
8 - 1.57" / 40.0 mm guns (4x2 guns), 1.94lbs / 0.88kg shells, 1936 Model Anti-aircraft guns in deck mounts with hoists on side, all amidships, all raised mounts - superfiring
8 - 0.91" / 23.0 mm guns in single mounts, 0.37lbs / 0.17kg shells, 1926 Model Breech loading guns in deck mounts on side, evenly spread
Weight of broadside 272 lbs / 124 kg
Shells per gun, main battery: 280

Armour:

Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.98" / 25 mm 0.20" / 5 mm 0.20" / 5 mm
2nd: 0.39" / 10 mm 0.83" / 21 mm -
3rd: 0.39" / 10 mm 0.83" / 21 mm -
4th: 0.20" / 5 mm - -

Armour deck: 0.59" / 15 mm, Conning tower: 0.98" / 25 mm

Machinery: Oil fired boilers, steam turbines, Geared drive, 2 shafts, 4,940 shp / 3,685 Kw = 20.00 kts
Range 8,650nm at 12.00 kts
Bunker at max displacement = 326 tons

Complement: 111 - 145

Cost: £0.528 million / $2.113 million

Distribution of weights at normal displacement:

Armament: 34 tons, 2.5 %
Armour: 103 tons, 7.6 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 15 tons, 1.1 %
- Armour Deck: 86 tons, 6.3 %
- Conning Tower: 3 tons, 0.2 %
Machinery: 131 tons, 9.6 %
Hull, fittings & equipment: 734 tons, 54.2 %
Fuel, ammunition & stores: 254 tons, 18.7 %
Miscellaneous weights: 100 tons, 7.4 %

Overall survivability and seakeeping ability:

Survivability (Non-critical penetrating hits needed to sink ship): 4,121 lbs / 1,869 Kg = 69.2 x 4.9 " / 125 mm shells or 1.5 torpedoes
Stability (Unstable if below 1.00): 1.20
Metacentric height 1.9 ft / 0.6 m
Roll period: 12.9 seconds
Steadiness - As gun platform (Average = 50 %): 78 %
- Recoil effect (Restricted arc if above 1.00): 0.32
Seaboat quality (Average = 1.00): 1.63

Hull form characteristics:

Hull has low quarterdeck
Block coefficient: 0.400
Length to Beam Ratio: 7.00 : 1
'Natural speed' for length: 17.28 kts
Power going to wave formation at top speed: 48 %
Trim (Max stability = 0, Max steadiness = 100): 48
Bow angle (Positive = bow angles forward): 18.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 16.34 ft / 4.98 m
- Forecastle (20 %): 14.70 ft / 4.48 m
- Mid (50 %): 14.70 ft / 4.48 m
- Quarterdeck (15 %): 6.69 ft / 2.04 m (14.70 ft / 4.48 m before break)
- Stern: 6.69 ft / 2.04 m
- Average freeboard: 13.63 ft / 4.15 m
Ship tends to be wet forward

Ship space, strength and comments:

Space - Hull below water (magazines/engines, low = better): 61.4 %
- Above water (accommodation/working, high = better): 197.7 %
Waterplane Area: 7,838 Square feet or 728 Square metres
Displacement factor (Displacement / loading): 184 %
Structure weight / hull surface area: 64 lbs/sq ft or 311 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.90
- Longitudinal: 2.59
- 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
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

***NOTE****
Bruce posted his follow-up design while I was typing this. This post refers to Kirk's original design and Bruce's previous comments as such
***NOTE***

Rather nice design overall, and I too appreciate the idea behind the design, something I don't share often enough with mine.

As to Bruce's concern over the usefulness of the torpedoes, perhaps they are to be fired at an advancing enemy to force them to maneuver at their disadvantage, granting more time for the convoy to disperse, or for heavier reinforcements to arrive.

I do agree that a nice ASW suite would make these rather perfect. I share the concern for using ASDIC at 20+kts, but also understand the rational as to why the 24+ kts speed is pertinent to the design.

While these are not intended to act against surface ships, I presume, a small group (2-3) could probably sufficiently hold off a destroyer or 2 for long enough for the convoy to scatter, perhaps even, in a desperate act that would lead to their destruction, a light cruiser may even be kept at bay.

Appreciate the comments and design, just a general response on points to answer those for any further posters.

Overall- Part of the points raised stem from the Dutch Hi-Lo philosophy. They can't "afford" enough Quality vessels to meet the needs, so low end vessels are designed to be able to fill the gaps.

-Speed - combination of fast enough to outstrip surfaced subs (expected to be 18+) and a 2-3 kt buffer over the 23kt Ijelsijks. Active ASW use would be at lower speeds.

However point taken that Speed might be luxury. I will note though that the difference in engine weight is only 30tons. Cost wise, I'm thinking the perceived marginal benefit exceeds the marginal cost.

-Torps - Good point. The origin is the S19 design which had concealed (due to Clieto) launchers. A large portion of the Dutch theater of operations include range-shortening islands and the possibility of night actions. Adding Torps then becomes part of the Hi-Lo design mix the Dutch have followed for some time. Obviously, since I spent my text explaining the Open Ocean use concept, this might not be a valid point for these.

On AA : Actually a design feature dating way back into the 1930s when the expected OPFOR was Indian flying boats from Diego Garcia air dropping torpedoes. Large, heavy hitting AA weapons were felt needed.

On ASW - it's intended the Misc weight inc the Dutch version of ASDIC, DCs, and Radar

Quoted

Originally posted by BruceDuncan
I appreciate you sharing the thoughts behind the design - and I suppose they are what I have the most concern about, rather than the individual facets of the design itself.

I am doubtful of the utility of the torpedo tubes on such a class of vessel, with the speed proposed. I think it unlikely that they could maneuver against an enemy to gain position to launch their torpedoes. I suppose that if the enemy task force was composed of Great War vintage battleships, these sloops might be successful, but even so the time under the guns of the enemy would make their survival questionable. I would consider recasting the design without the torpedo tubes.

Likewise, I think the speed is excessive. Sonar at this period suffers from significant drop off above 20 knots. Opting for less speed, rather than more, I think would pay dividends - and you could find in the design sufficient tonnage for a reasonable antisubmarine armament, unless that comprises the 100 tons miscellaneous weight already incorporated.

I *like* the heavy antiaircraft armament, particularly if it is matched with good fire control. Others may call it excessive.

For comparison, here's the sloop with a transom, but without the TT (as Duncan had), with the engines redlined to 27knots- any faster and she needs a different hull form.

Oh, one point - I think that alt version was in SS3, so can't be used (unless I missed something).

Overall, Staying with the 21kts of the S19/44 series makes sense, ramping up to 25kts works ok. 27 seems not good.

Torpedoes... I guess the question is opportunity cost. If I can tuck twins or triples under the 'en echelon' 40mm platforms, to give them a sting in close surface actions...how much "real life" hassle would that cause the designers/trainers/armorers?

In a related question- would foresight be seeing ASW torps yet? Acoustic homers I think have been floated, and shot down concept wise, but if it's a concept that's just not there technologically, it would make sense to plan on that.

Comments?

S52, Netherlands Schnell Escort laid down 1941

Displacement:
1,099 t light; 1,187 t standard; 1,356 t normal; 1,491 t full load

Dimensions: Length overall / water x beam x draught
303.87 ft / 298.56 ft x 42.65 ft x 9.32 ft (normal load)
92.62 m / 91.00 m x 13.00 m x 2.84 m

Armament:
4 - 4.92" / 125 mm guns (2x2 guns), 59.52lbs / 27.00kg shells, 1926 Model
Dual purpose guns in deck mounts with hoists
on centreline ends, evenly spread
8 - 1.57" / 40.0 mm guns (2x4 guns), 1.94lbs / 0.88kg shells, 1936 Model
Anti-aircraft guns in deck mounts with hoists
on centreline ends, evenly spread, all raised mounts
8 - 1.57" / 40.0 mm guns (2x4 guns), 1.94lbs / 0.88kg shells, 1936 Model
Anti-aircraft guns in deck mounts
on side, all amidships, all raised mounts - superfiring
8 - 0.91" / 23.0 mm guns in single mounts, 0.37lbs / 0.17kg shells, 1926 Model
Breech loading guns in deck mounts
on side ends, evenly spread
Weight of broadside 272 lbs / 123 kg
Shells per gun, main battery: 370

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 0.98" / 25 mm 229.66 ft / 70.00 m 8.01 ft / 2.44 m
Ends: Unarmoured
Main Belt covers 118 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.98" / 25 mm 0.20" / 5 mm 0.20" / 5 mm
2nd: 0.39" / 10 mm 0.83" / 21 mm -
3rd: 0.39" / 10 mm 0.83" / 21 mm -
4th: 0.20" / 5 mm - -

- Armour deck: 0.59" / 15 mm, Conning tower: 0.98" / 25 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 13,452 shp / 10,035 Kw = 27.00 kts
Range 8,650nm at 12.00 kts
Bunker at max displacement = 304 tons

Complement:
111 - 145

Cost:
£0.722 million / $2.890 million

Distribution of weights at normal displacement:
Armament: 34 tons, 2.5 %
Armour: 179 tons, 13.2 %
- Belts: 74 tons, 5.5 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 13 tons, 1.0 %
- Armour Deck: 89 tons, 6.6 %
- Conning Tower: 3 tons, 0.2 %
Machinery: 356 tons, 26.2 %
Hull, fittings & equipment: 431 tons, 31.8 %
Fuel, ammunition & stores: 257 tons, 18.9 %
Miscellaneous weights: 100 tons, 7.4 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,143 lbs / 518 Kg = 19.2 x 4.9 " / 125 mm shells or 0.6 torpedoes
Stability (Unstable if below 1.00): 1.29
Metacentric height 2.2 ft / 0.7 m
Roll period: 12.1 seconds
Steadiness - As gun platform (Average = 50 %): 52 %
- Recoil effect (Restricted arc if above 1.00): 0.23
Seaboat quality (Average = 1.00): 0.85

Hull form characteristics:
Hull has low quarterdeck
and transom stern
Block coefficient: 0.400
Length to Beam Ratio: 7.00 : 1
'Natural speed' for length: 20.65 kts
Power going to wave formation at top speed: 64 %
Trim (Max stability = 0, Max steadiness = 100): 61
Bow angle (Positive = bow angles forward): 18.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 16.34 ft / 4.98 m
- Forecastle (20 %): 14.70 ft / 4.48 m
- Mid (50 %): 14.70 ft / 4.48 m
- Quarterdeck (15 %): 6.69 ft / 2.04 m (14.70 ft / 4.48 m before break)
- Stern: 6.69 ft / 2.04 m
- Average freeboard: 13.63 ft / 4.15 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 115.5 %
- Above water (accommodation/working, high = better): 205.2 %
Waterplane Area: 8,135 Square feet or 756 Square metres
Displacement factor (Displacement / loading): 107 %
Structure weight / hull surface area: 37 lbs/sq ft or 181 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.51
- Longitudinal: 1.48
- Overall: 0.56
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is excellent
Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

Quoted

Oh, one point - I think that alt version was in SS3, so can't be used (unless I missed something).

If you are referring to the Schichau design, I assure you it's to SS2 - it's the only version I have.

Documentation here

I like the intial design and the background info which is very helpful.
I've had several in-depth thoughts on sloops for several months but not really put any of them into action.

The main armament seems fine, powerful enough to defend herself and deal with smaller local threats. The 40mm fit seems a tad heavy to me but that's personal taste. I think 25knts should be ok, the 27 kt version might not be worth it. A sloop won't need too much margin of speed when on convoy and as we know ASDIC speeds aren't high either.

Personally I think the torpedoes have a role, I would go for one qaud bank myself rather than two triples. Torpedoes have deterrent effect, an enemy raider or attacker might not wish to venture too close and risk damage and a quick "fire and dash" technique to buy time for a convoy to scatter might be useful too. IMHO four tubes should suffice. Otherwise you risk builidng a slow DD and using it as such when it can't really fulfill the DD role.

A couple of notes-
On the hull strength, I think I misunderstood what folks were saying. I think now they were indicating it should be 1.0, which is incorrect. I originally was aiming for that, finished the design at 0.88 or so and started looking for ways to lighten the ship etc, then I checked the Design rules-

Quoted

Point 1: Hull strength.
a) Relative composite hull strength should not drop below 1.00 except for the light fast combattants (<6000 tons standard; >24kn)
b) Relative cross-sectional hull strength of light fast combattants of 0-3,000 tons standard should not drop below 0.5

So at 25,26 or 27 knots, 0.5 is all that is required. As such, the 0.62 (?) I have is a 24% reserve.

Conceptually, if you consider a hull with perhaps a A/B Q TT TT X/Y arms layout, those centerline TTs can fire on each broadside.

On earlier RN DDs, you see a Searchlight tower in 'Q', with offset AA

So I was borrowing from that and conceptually moving the "TT" spots off centerline and putting a platform over them for the 40mm- allowing fore & aft fire over the deck gear, while saving space. "Q" becomes the searchlight/TDC tower.

Since proposing it, I've thought spacewise it might be more reasonable to only put twins in those side positions, or dispense with them. The single Quad bank would have the same #, but I don't think I have lengthwise room for a centerline emplacement.

I'm not convinced that you'd want an open ocean escort to be lightly built though. Unlike a destroyer you're going to spend lots of time thumping around the seas and likely bumping into things on patrol duties. I would have thought a hull strength of 1.00+ to have been extremely useful for such a ship.

I think it's interesting to compare to the historical Hunt Class destroyer escorts of the RN. The ships are similar size, speed and role. However, the Hunts have considerably less armament in the 4 or 6x4" and 4x40mm. Quadruple 40mm mountings are very heavy, especially if stabilised too. The Hunts also don't have any armour. In service the vessels were found to be considerably overloaded with little stability margin due to excess topweight - and not really open ocean escort vessels.

Good point, what is the armour for? Doesn't seem worth the weight on a vessel this small. Could even be counterproductive.

RA,

The Type I Hunts shipped the same armanent as thier precursor on a hull 2m narrower- 8.8m, while the Type IIs added 0.8m to address that. Meanwhile I've got a broader, shallower 13m wide hull to accomodate the larger guns. The weight of the stabilized AA mountings is precisely why I discussed using the "other" armor representing that extra top weight - so it's modeled as up high.

As for hull strength- my point is that by our rules "0.5" is "normal" for this type of ship, and in this case the hull is built with a 24% reserve, they are not nearly as lightly built as a standard destroyer.

Per our rules, it's built stronger than needed. Now I'll grant that if I dropped a knot, suddenly I'd need 1.0... but that's also just the rules we sim by.

RA/Hood
Armor : Armor was an afterthought, echoing a USN DD class which had anti-strafing armor. Due to the 2nd line inter-island use and the undesirability of bullets in boilers, it was a 'why not?'

I rarely view armor as capable of doing damage, it's not like anyone will be tossing SAP/AP shells to be fused anyhow, though the belt should actually stop any light HE rounds- though the deck won't stop splinters. I think the extra weight wound up helping seakeeping too...

I seem to remember that the "armour" as such was simply using high tensile steel in the construction rather than actual armour, avoiding thickening the deck too much to keep down weight on the flush decked ships. Bear in mind that the hull plates will likely be 5-10mm thick anyway. Higher hull strength will generally mean more solid construction overall, rather than just the bits that are treated as armour here.

Sorry got busy and then tired and wandered off, basically I flaked.

The Fletcher class had "0.5" STS protection for engines, boilers (both decks and sides), pilothouse and 0,75" STS over the 5" gun director. "

Which means RA is correct, and it's not High Quality face hardened armor.... but STS is a low grade armor steel and it additional to the basic hull.

It's a "cost" of 160 tons of armor. Completely eliminating the armor brings comp hull up to 0.88. Given the primary use, applying armor for a 2nd line contingency does seem a little much, esp over a large production run.

Hoo and I are working on a compromise vessel, as the oceanic requirements are similar. There, the armor is indeed just a more robust hull thickness.