Design Bureau Hong Kong

[Guinness]

Handling arrangements varied. By WW2 many of the new DP guns like the 5"L38 and the various RN DP "below decks" mountings had separate handling spaces from which the hoists from the magazines terminated. Usually there was another hoist like mechanism there that actually fed the gun's loading arrangement.

This was certainly post World War I though. Furthermore, I'd be surprised if you'd have ever seen power ramming on a single mounted 6" gun in our timeframe. US triple 6"L47 mounts as in the Brooklyns, etc certainly did have power ramming, and I suspect contemporary London Treaty cruisers did as well, but I'd be very surprised if you could find a single power rammed mount OTL.

If we're even talking about power ramming, I presume you mean that these mounts would be enclosed, which seems to me to be a realism issue as well for 1920. Enclosed mounts on destroyers were only ever really adopted for DP guns, and this was mostly not for protection per-sea, but to provide weather protection for the more exposed crews. For instance, on the first US DP equipped destroyers B position lost the shield that protected A position from it's blast, but which also provided protection from water and spray.

At any rate, we see here the high difficulty of building a 6" armed destroyer. I think it could succeed with something more like 4 guns, with only one before the bridge, to avoid "bow-heaviness" as the Germans observed with their 6" gunned DDs.

[maddox]

The 5" mount I know. Used on all modern US BB's, and a lot of smaller vessels. The 5" L38 Twin Mount, and Hoist (in Springsharp terms)



The turret itself rests on a deck mounted turntable, with a reinforcing magazine/hoist setup. But not a barbette.
A barbette implies that there is more revolving body below deck.

According to this text , the setup was developed and build in the early 30's.

Loading is done by hand, but power-rammed.


More information usefull to compare,

[Kaiser Kirk]

A fuller hull could also help avoid the "bow heaviness", long thin hulls with large weights up front do have issues. Lower L:B and higher BC means more volume in the bow.

The USN had a 20kt gunboat, the 2,000t Erie class, with 4x 6", A/B/Y/X, which I haven't read anything negative about her seakeeping....which doesn't mean there wasn't a problem, just that I haven't seen it in writeups.

[Guinness]

Good seaworthiness was an expressed design requirement of the Eries. Being substantially slower than a destroyer helped. They were only good for 20 knots on 7000 hp, so we can expect their machinery plants were quite small compared to the big DDs of the day. They also had full hull forms and a relatively low L/B ratio of about 8. If memory serves they were armored as well, but I'm not home this weekend, so a reference that could tell me quickly isn't at hand.

At any rate, these ships were built to "cruiser" standards (and then some in some regards), and would be regarded as much more heavily constructed than a destroyer. They're probably more closely akin to the big coast guard cutters of the era or some of the interwar British sloops than anything else.

[Walter]

The turret itself rests on a deck mounted turntable, with a reinforcing magazine/hoist setup. But not a barbette.
A barbette implies that there is more revolving body below deck.

Actually, in that picture '8' is the barbette.

[maddox]

Walter, a very very "thin" barbette then.  It's just a gear-ring and turntable that is bolted directly to the deck and reinforcing frame members.

[Guinness]

5"L38's for the most part rode on a "base ring" mounting, which is more or less exactly what Maddox describes. This was nothing more than the bits you might expect to find at the top of a barbette anyway. The bits that hang down below decks were minimal, however. Just what was needed to hoist ammunition above.

That doesn't mean that they couldn't be mounted on a barbette, however. Most smaller ship installations had them sitting either on the deck or on a deckhouse which enclosed the ammunition handling space below. On US battleships I'm pretty sure they had armored barbettes below them. What I can't remember is if those went all the way down to the armored deck or not. When I get home, I can look in Friedman and see.

BTW: this is an excellent resource for US gun mounts:
http://hnsa.org/doc/guncat/index.htm

[maddox]

The  5" /38's were in essence the same mounts on the Iowa class and on the Philadephia cruisers.

Maybe that more armor was placed around the 5" magazines on the BB's, but it should surprise me if that was integral to the mounts.

[Kaiser Kirk]

Erie : Yes, they were designed for 3" of armored belt.  I rather like them over the Dutch Flores class.  Anyhow, they represent one known point where a small ship had 4x6" and reasonable seakeeping, the German DDs represent the other end, somewhere in between is the limit...but high L:B and low BC combos can be expected to bury the bows in high seas.

5"/38 - as posted, base ring not barbette.   The earliest pedestal mounts had the hoist come up behind them.   What is interesting to me is Navweaps diagram of the the twin 5.25" seems to show a stalk structure, suggesting the Brits went to a turret & barbette for that twin, which admittedly was a very heavy rotating structure (87t?)

[Guinness]

I sadly don't have a resource at hand for the RN 5.25" mount, but my understanding about it is it had a round rotating structure below it, but did not necessarily need a barbette to support it. It certainly was heavy though.

I did look in Friedman, and there wasn't an internal diagram that showed arrangements of the 5"L38s as I'd hoped, but I think from the photos of the the various BBs carrying them that it's clear they were all mounted on deckhouse/handling room arrangements and had no barbettes below them. Friedman says the Iowas secondary mounts had 80lb (so 2") STS armor. My guess is the hoists below had splinter protection as well.

On a side note, I've been messing with an idea or two for an Ottoman TB Flotilla leader. A 1000t ship built to destroyer rules resulted in something distinctly Dutch in complexion, which is no surprise, as I started with a the previous class of dutch style 120mm armed DDs. I also tried a light cruiser architecture ship, which came out at 3000t light with pretty good legs, 29+ knots, 1.1 seakeeping, 5x150mm in singles all on the freeboard deck, 6x21" torpedoes, some misc weight for mines, and fire control, but completely unarmored except for gun shields and a conning tower. I'm not sure that ship would be worth it.

So the point is: certainly 6" armed "leaders" make for difficult compromises.

[Logi]

Taking another crack at the DDs, this time with the lowered seakeeping.

20DD2, RRC Destroyer laid down 1920 (Engine 1916)

Displacement:
   1,000 t light; 1,040 t standard; 1,124 t normal; 1,191 t full load

Dimensions: Length overall / water x beam x draught
   373.00 ft / 360.00 ft x 32.00 ft x 8.90 ft (normal load)
   113.69 m / 109.73 m x 9.75 m  x 2.71 m

Armament:
      4 - 4.72" / 120 mm guns in single mounts, 52.72lbs / 23.91kg shells, 1920 Model
     Breech loading guns in deck mounts
     on centreline ends, evenly spread, 2 raised mounts - superfiring
   Weight of broadside 211 lbs / 96 kg
   Shells per gun, main battery: 150
   9 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   1.00" / 25 mm   0.50" / 13 mm            -

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 34,257 shp / 25,556 Kw = 34.50 kts
   Range 3,000nm at 12.00 kts
   Bunker at max displacement = 151 tons

Complement:
   96 - 126

Cost:
   £0.342 million / $1.367 million

Distribution of weights at normal displacement:
   Armament: 26 tons, 2.3 %
   Armour: 10 tons, 0.9 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 10 tons, 0.9 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 624 tons, 55.5 %
   Hull, fittings & equipment: 285 tons, 25.4 %
   Fuel, ammunition & stores: 124 tons, 11.0 %
   Miscellaneous weights: 54 tons, 4.8 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     178 lbs / 81 Kg = 3.4 x 4.7 " / 120 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.10
   Metacentric height 1.1 ft / 0.3 m
   Roll period: 12.9 seconds
   Steadiness   - As gun platform (Average = 50 %): 53 %
         - Recoil effect (Restricted arc if above 1.00): 0.17
   Seaboat quality  (Average = 1.00): 0.53

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.384
   Length to Beam Ratio: 11.25 : 1
   'Natural speed' for length: 18.97 kts
   Power going to wave formation at top speed: 65 %
   Trim (Max stability = 0, Max steadiness = 100): 100
   Bow angle (Positive = bow angles forward): 31.60 degrees
   Stern overhang: 5.00 ft / 1.52 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      13.00 ft / 3.96 m
      - Forecastle (20 %):   10.00 ft / 3.05 m
      - Mid (50 %):      8.00 ft / 2.44 m
      - Quarterdeck (15 %):   7.00 ft / 2.13 m
      - Stern:      7.00 ft / 2.13 m
      - Average freeboard:   8.62 ft / 2.63 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 202.1 %
      - Above water (accommodation/working, high = better): 52.8 %
   Waterplane Area: 7,034 Square feet or 654 Square metres
   Displacement factor (Displacement / loading): 40 %
   Structure weight / hull surface area: 28 lbs/sq ft or 135 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 0.50
      - Overall: 0.50
   Hull space for machinery, storage, compartmentation is extremely poor
   Room for accommodation and workspaces is cramped
   Caution: Lacks seaworthiness - very limited seakeeping ability

Trial Speed: 35.5 kts

Misc Weights:
25t: Fire Control
18t: 9 21" Torpedoes (or 18 21" Torpedoes)
10t: Minesweeping Gear
  1t: Construction Reserve

[Logi]

Considering a 200t TB.

19TB1, RRC Destroyer laid down 1919 (Engine 1916)

Displacement:
   200 t light; 207 t standard; 239 t normal; 265 t full load

Dimensions: Length overall / water x beam x draught
   230.00 ft / 222.00 ft x 20.19 ft x 4.90 ft (normal load)
   70.10 m / 67.67 m x 6.15 m  x 1.49 m

Armament:
     2 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1919 Model
     Quick firing guns in deck mounts
     on centreline ends, evenly spread
     2 - 0.50" / 12.7 mm guns in single mounts, 0.06lbs / 0.03kg shells, 1919 Model
     Machine guns in deck mounts
     on centreline, all amidships
   Weight of broadside 26 lbs / 12 kg
   Shells per gun, main battery: 150
   9 - 21.0" / 533.4 mm above water torpedoes

Armour:
  - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.35" / 9 mm         -               -

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 5,952 shp / 4,440 Kw = 27.00 kts
   Range 3,000nm at 12.00 kts
   Bunker at max displacement = 58 tons

Complement:
   29 - 39

Cost:
   £0.058 million / $0.232 million

Distribution of weights at normal displacement:
   Armament: 3 tons, 1.4 %
   Armour: 1 tons, 0.4 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 1 tons, 0.4 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 120 tons, 50.3 %
   Hull, fittings & equipment: 66 tons, 27.8 %
   Fuel, ammunition & stores: 39 tons, 16.4 %
   Miscellaneous weights: 9 tons, 3.8 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     61 lbs / 28 Kg = 4.7 x 3.0 " / 75 mm shells or 0.1 torpedoes
   Stability (Unstable if below 1.00): 1.08
   Metacentric height 0.5 ft / 0.2 m
   Roll period: 11.7 seconds
   Steadiness   - As gun platform (Average = 50 %): 30 %
         - Recoil effect (Restricted arc if above 1.00): 0.08
   Seaboat quality  (Average = 1.00): 0.34

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.381
   Length to Beam Ratio: 11.00 : 1
   'Natural speed' for length: 14.90 kts
   Power going to wave formation at top speed: 64 %
   Trim (Max stability = 0, Max steadiness = 100): 53
   Bow angle (Positive = bow angles forward): 30.00 degrees
   Stern overhang: 1.07 ft / 0.33 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      12.00 ft / 3.66 m
      - Forecastle (20 %):   9.00 ft / 2.74 m
      - Mid (50 %):      6.00 ft / 1.83 m
      - Quarterdeck (15 %):   4.00 ft / 1.22 m
      - Stern:      4.00 ft / 1.22 m
      - Average freeboard:   6.64 ft / 2.02 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 176.8 %
      - Above water (accommodation/working, high = better): -42.4 %
   Waterplane Area: 2,734 Square feet or 254 Square metres
   Displacement factor (Displacement / loading): 50 %
   Structure weight / hull surface area: 16 lbs/sq ft or 79 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 0.64
      - Overall: 0.51
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is extremely poor
   Caution: Lacks seaworthiness - very limited seakeeping ability

9t ( 9 21" Torpedoes)

[Guinness]

I'm working on art for the OE 200t boat now. I think I can say with certainty that fitting 2x75mm guns and 9 21" TTs on a boat 230 feet long is going to be very close to impossible. On the OE boat, the pair of TTS takes up 16% of overall length, and 40% of overall beam. Even if you cram your tubes in back to front, they'd take up nearly 40% of your overall length (and that's before the guns, funnels, bridge, and other necessary stuff).

[Logi]

Drawing of the 19TB: scale is 2 pixel = 1 feet

Seems to fit....



I'm probably going to go back to the design see if I can adjust the B/C to be larger.

[Logi]

Adjusted the B/C to 0.415

19TB1, RRC Destroyer laid down 1919 (Engine 1916)

Displacement:
   200 t light; 206 t standard; 239 t normal; 265 t full load

Dimensions: Length overall / water x beam x draught
   230.00 ft / 222.00 ft x 20.19 ft x 4.50 ft (normal load)
   70.10 m / 67.67 m x 6.15 m  x 1.37 m

Armament:
      2 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1919 Model
     Quick firing guns in deck mounts
     on centreline ends, evenly spread
      2 - 0.50" / 12.7 mm guns in single mounts, 0.06lbs / 0.03kg shells, 1919 Model
     Machine guns in deck mounts
     on centreline, all amidships
   Weight of broadside 26 lbs / 12 kg
   Shells per gun, main battery: 100
   9 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   1.00" / 25 mm         -               -
   2nd:   1.00" / 25 mm         -               -

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 6,117 shp / 4,563 Kw = 27.00 kts
   Range 3,000nm at 12.00 kts
   Bunker at max displacement = 59 tons

Complement:
   29 - 39

Cost:
   £0.058 million / $0.232 million

Distribution of weights at normal displacement:
   Armament: 3 tons, 1.4 %
   Armour: 3 tons, 1.3 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 3 tons, 1.3 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 120 tons, 50.3 %
   Hull, fittings & equipment: 65 tons, 27.0 %
   Fuel, ammunition & stores: 39 tons, 16.2 %
   Miscellaneous weights: 9 tons, 3.8 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     60 lbs / 27 Kg = 4.6 x 3.0 " / 75 mm shells or 0.1 torpedoes
   Stability (Unstable if below 1.00): 1.09
   Metacentric height 0.5 ft / 0.2 m
   Roll period: 11.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 29 %
         - Recoil effect (Restricted arc if above 1.00): 0.08
   Seaboat quality  (Average = 1.00): 0.28

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.415
   Length to Beam Ratio: 11.00 : 1
   'Natural speed' for length: 14.90 kts
   Power going to wave formation at top speed: 65 %
   Trim (Max stability = 0, Max steadiness = 100): 58
   Bow angle (Positive = bow angles forward): 30.00 degrees
   Stern overhang: 1.07 ft / 0.33 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      12.00 ft / 3.66 m
      - Forecastle (15 %):   8.00 ft / 2.44 m
      - Mid (50 %):      6.00 ft / 1.83 m
      - Quarterdeck (10 %):   4.00 ft / 1.22 m
      - Stern:      4.00 ft / 1.22 m
      - Average freeboard:   6.29 ft / 1.92 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 176.7 %
      - Above water (accommodation/working, high = better): -41.6 %
   Waterplane Area: 2,784 Square feet or 259 Square metres
   Displacement factor (Displacement / loading): 48 %
   Structure weight / hull surface area: 16 lbs/sq ft or 77 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 0.54
      - Overall: 0.50
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is extremely poor
   Ship has quick, lively roll, not a steady gun platform
   Caution: Lacks seaworthiness - very limited seakeeping ability

9t ( 9 21" Torpedoes)