Yet another destroyer ...

[Borys]

Ahoj!
What could - or should - I do to improve this ship? I'm lost in the various speed and freeboard threads pertaining to destroyers, so be gentle ...
:D

I want it to be more less like this vessel:
http://www.german-navy.de/hochseeflotte/ships/torpedoboats/gtb1918mob/index.html

Enter ship name, Enter country Enter ship type laid down 1921 (Engine 1916)

Displacement:
   1 495 t light; 1 559 t standard; 1 798 t normal; 1 989 t full load

Dimensions: Length overall / water x beam x draught
   319,00 ft / 310,00 ft x 35,00 ft x 11,60 ft (normal load)
   97,23 m / 94,49 m x 10,67 m  x 3,54 m

Armament:
      4 - 4,50" / 114 mm guns in single mounts, 50,00lbs / 22,68kg shells, 1921 Model
     Quick firing guns in deck mounts
     on centreline, evenly spread, 2 raised mounts
     Aft Main mounts separated by engine room
   Weight of broadside 200 lbs / 91 kg
   Shells per gun, main battery: 250
   6 - 20,0" / 508 mm above water torpedoes

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 1 shaft, 47 341 shp / 35 317 Kw = 33,00 kts
   Range 1 800nm at 20,00 kts
   Bunker at max displacement = 431 tons

Complement:
   137 - 179

Cost:
   £0,574 million / $2,296 million

Distribution of weights at normal displacement:
   Armament: 23 tons, 1,3%
   Machinery: 1 100 tons, 61,2%
   Hull, fittings & equipment: 324 tons, 18,0%
   Fuel, ammunition & stores: 303 tons, 16,9%
   Miscellaneous weights: 48 tons, 2,7%

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     284 lbs / 129 Kg = 6,2 x 4,5 " / 114 mm shells or 0,2 torpedoes
   Stability (Unstable if below 1.00): 1,85
   Metacentric height 2,8 ft / 0,9 m
   Roll period: 8,8 seconds
   Steadiness   - As gun platform (Average = 50 %): 22 %
         - Recoil effect (Restricted arc if above 1.00): 0,06
   Seaboat quality  (Average = 1.00): 0,20

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0,500
   Length to Beam Ratio: 8,86 : 1
   'Natural speed' for length: 17,61 kts
   Power going to wave formation at top speed: 74 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 0,00 degrees
   Stern overhang: 9,00 ft / 2,74 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      18,00 ft / 5,49 m
      - Forecastle (20%):   17,00 ft / 5,18 m
      - Mid (25%):      16,00 ft / 4,88 m (9,00 ft / 2,74 m aft of break)
      - Quarterdeck (15%):   9,00 ft / 2,74 m
      - Stern:      9,00 ft / 2,74 m
      - Average freeboard:   11,06 ft / 3,37 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 210,5%
      - Above water (accommodation/working, high = better): 60,5%
   Waterplane Area: 6 949 Square feet or 646 Square metres
   Displacement factor (Displacement / loading): 48%
   Structure weight / hull surface area: 29 lbs/sq ft or 140 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0,48
      - Longitudinal: 0,79
      - Overall: 0,50
   Hull space for machinery, storage, compartmentation is extremely poor
   Room for accommodation and workspaces is cramped
   Ship has quick, lively roll, not a steady gun platform
   Caution: Lacks seaworthiness - very limited seakeeping ability

[The Rock Doctor]

As a starting point, tweek the hull dimensions so she's closer to 10:1 - I recognize your dimensions are ~historical, but she's still on the pudgy side for a destroyer.

This should reduce the amount of machinery needed for 33 kts, and thereby bring you hull strength up to acceptable levels.

Second, adjust trim so your steadiness is 50% - this will do wonders for your seakeeping.

[Borys]

Ahoj!
Genius!


Enter ship name, Enter country Enter ship type laid down 1921 (Engine 1916)

Displacement:
   1 302 t light; 1 361 t standard; 1 579 t normal; 1 753 t full load

Dimensions: Length overall / water x beam x draught
   319,00 ft / 310,00 ft x 31,00 ft x 11,50 ft (normal load)
   97,23 m / 94,49 m x 9,45 m  x 3,51 m

Armament:
      4 - 4,50" / 114 mm guns in single mounts, 50,00lbs / 22,68kg shells, 1921 Model
     Quick firing guns in deck mounts
     on centreline, evenly spread, 2 raised mounts
     Aft Main mounts separated by engine room
      2 - 0,43" / 11,0 mm guns in single mounts, 0,04lbs / 0,02kg shells, 1921 Model
     Machine guns in deck mounts
     on centreline, all forward, all raised mounts - superfiring
The MG are either on bridge wings, or in place of the historical single tubes
   Weight of broadside 200 lbs / 91 kg
   Shells per gun, main battery: 250
   6 - 20,0" / 508 mm above water torpedoes

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 1 shaft, 42 449 shp / 31 667 Kw = 33,00 kts
   Range 1 800nm at 20,00 kts
   Bunker at max displacement = 392 tons

Complement:
   124 - 162

Cost:
   £0,499 million / $1,994 million

Distribution of weights at normal displacement:
   Armament: 23 tons, 1,4%
   Machinery: 937 tons, 59,3%
   Hull, fittings & equipment: 294 tons, 18,6%
   Fuel, ammunition & stores: 277 tons, 17,6%
   Miscellaneous weights: 48 tons, 3,0%
24 tonnes are for the 2x3x20" TT
24 tonnes are for mine rails for 24 mines

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     203 lbs / 92 Kg = 4,5 x 4,5 " / 114 mm shells or 0,2 torpedoes
   Stability (Unstable if below 1.00): 1,12
   Metacentric height 1,1 ft / 0,3 m
   Roll period: 12,6 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0,18
   Seaboat quality  (Average = 1.00): 0,50

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0,500
   Length to Beam Ratio: 10,00 : 1
   'Natural speed' for length: 17,61 kts
   Power going to wave formation at top speed: 72 %
   Trim (Max stability = 0, Max steadiness = 100): 99
   Bow angle (Positive = bow angles forward): 0,00 degrees
   Stern overhang: 9,00 ft / 2,74 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      18,00 ft / 5,49 m
      - Forecastle (20%):   17,00 ft / 5,18 m
      - Mid (25%):      16,00 ft / 4,88 m (9,00 ft / 2,74 m aft of break)
      - Quarterdeck (15%):   9,00 ft / 2,74 m
      - Stern:      9,00 ft / 2,74 m
      - Average freeboard:   11,06 ft / 3,37 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 206,5%
      - Above water (accommodation/working, high = better): 55,2%
   Waterplane Area: 6 155 Square feet or 572 Square metres
   Displacement factor (Displacement / loading): 47%
   Structure weight / hull surface area: 27 lbs/sq ft or 132 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0,47
      - Longitudinal: 0,87
      - 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

[Sachmle]

Well, I can't really think of anything that Rocky didn't say to fix the other. Unfortunately it's Cross-sectional is still to low (0.47 btw) on the last effort. I did however manage to sim the Real one, sorta. I used the dimensions and stats from german-navy and NavWeaps for weights for shells, torpedoes, and mines. Unfortunately the 38,000shp listed on german-navy only gets you 32.8154 knots in SS. The listed top speed of 35kts was 50,503shp and drove the cross-sectional down to 0.35, the overall down to 0.38 and the stab/sea/stead to 1.14/0.50/50.(Yay Stab/Sea/Stead..Boo CS/OV)

Noticed that we may be over weighting mines ALOT since it's 1t per mine right now, but the heaviest WWI mine used by Germany (Granted haven't checked other nations yet) was ~750lbs or 0.375 short ton/0.3348 long ton (not sure which one we use.) Question on that whole thing is: Should we just make some obligatory weight, say 5t for laying equip/rails and then pay per mine @ weight of actual mine? This ship could lay 40 mines and the mines weighed 750lbs/340.194kg(0.375t) so paying 1t per mine(as is rule atm) you overpay by 25t. Now I could see 5-10t of that being rails, ect.. Anyway, I'll get off my soap box for now and just post the design. Remember, it's not to OUR ruleset as to weights for torps/mines, but RL weights

Side note: German-navy.de list crew size as 117, SS says 113-148...so maybe SS isn't so bad at guessing crew size after all.

Type 1918Mob, Deutschland Großes Torpedoboot laid down 1918

Displacement:
   1,154 t light; 1,190 t standard; 1,397 t normal; 1,563 t full load

Dimensions: Length overall / water x beam x draught
   306.42 ft / 298.56 ft x 29.86 ft x 12.14 ft (normal load)
   93.40 m / 91.00 m x 9.10 m  x 3.70 m

Armament:
     2 - 4.13" / 105 mm guns in single mounts, 38.36lbs / 17.40kg shells, 1918 Model
     Quick firing guns in deck mounts
     on centreline ends, evenly spread
     2 - 4.13" / 105 mm guns in single mounts, 38.36lbs / 17.40kg shells, 1918 Model
     Quick firing guns in deck mounts
     on centreline, all amidships, all raised mounts - superfiring
     4 - 0.30" / 7.7 mm guns in single mounts, 0.01lbs / 0.01kg shells, 1918 Model
     Machine guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 153 lbs / 70 kg
   Shells per gun, main battery: 80
   6 - 19.7" / 500 mm above water torpedoes

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 38,000 shp / 28,348 Kw = 32.82 kts
   Range 2,000nm at 20.00 kts
   Bunker at max displacement = 373 tons

Complement:
   113 - 148

Cost:
   £0.336 million / $1.345 million

Distribution of weights at normal displacement:
   Armament: 18 tons, 1.3 %
   Machinery: 807 tons, 57.7 %
   Hull, fittings & equipment: 297 tons, 21.2 %
   Fuel, ammunition & stores: 243 tons, 17.4 %
   Miscellaneous weights: 33 tons, 2.4 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     218 lbs / 99 Kg = 6.2 x 4.1 " / 105 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.10
   Metacentric height 1.0 ft / 0.3 m
   Roll period: 12.7 seconds
   Steadiness   - As gun platform (Average = 50 %): 57 %
         - Recoil effect (Restricted arc if above 1.00): 0.18
   Seaboat quality  (Average = 1.00): 0.60

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.452
   Length to Beam Ratio: 10.00 : 1
   'Natural speed' for length: 17.28 kts
   Power going to wave formation at top speed: 72 %
   Trim (Max stability = 0, Max steadiness = 100): 96
   Bow angle (Positive = bow angles forward): 9.90 degrees
   Stern overhang: 4.43 ft / 1.35 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      19.69 ft / 6.00 m
      - Forecastle (20 %):   17.06 ft / 5.20 m
      - Mid (30 %):      17.06 ft / 5.20 m (8.53 ft / 2.60 m aft of break)
      - Quarterdeck (15 %):   8.53 ft / 2.60 m
      - Stern:      8.53 ft / 2.60 m
      - Average freeboard:   11.30 ft / 3.44 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 198.1 %
      - Above water (accommodation/working, high = better): 56.0 %
   Waterplane Area: 5,694 Square feet or 529 Square metres
   Displacement factor (Displacement / loading): 48 %
   Structure weight / hull surface area: 28 lbs/sq ft or 138 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.25
      - Overall: 0.54
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is cramped
   Caution: Lacks seaworthiness - very limited seakeeping ability

Misc Weight:
40 340kg mines = 15t
6 1,365kg G7 50cm Torpedoes = 9t
3t = mines rails
6t = TT weight

[Guinness]

Noticed that we may be over weighting mines ALOT since it's 1t per mine right now, but the heaviest WWI mine used by Germany (Granted haven't checked other nations yet) was ~750lbs or 0.375 short ton/0.3348 long ton (not sure which one we use.) Question on that whole thing is: Should we just make some obligatory weight, say 5t for laying equip/rails and then pay per mine @ weight of actual mine? This ship could lay 40 mines and the mines weighed 750lbs/340.194kg(0.375t) so paying 1t per mine(as is rule atm) you overpay by 25t. Now I could see 5-10t of that being rails, ect.. Anyway, I'll get off my soap box for now and just post the design. Remember, it's not to OUR ruleset as to weights for torps/mines, but RL weights

I've noticed the same thing, that our blanket 1t per mine weight may or may not be realistic. If ever we do tinker with that rule, I'd advocate some flat weight for the ability to lay mines, then a per-mine weight. This would also reflect the fact that minelaying capability generally had to be built (or refitted) into a ship to be truly effective.

[Borys]

Ahoj!
As I like everything hefty, I was on the forefront of the "one mine - one tonne" campaign :)

Does the quoted weight of the mine included the wheeled boogie/anchor, and the steel chain linking the two? Or is that only the horny ball?

Very nice sim, although the number of shells for the 10.5cm guns looks very low.

Borys

[Sachmle]

Ahoj!
As I like everything hefty, I was on the forefront of the "one mine - one tonne" campaign :)

Does the quoted weight of the mine included the wheeled boogie/anchor, and the steel chain linking the two? Or is that only the horny ball?

Very nice sim, although the number of shells for the 10.5cm guns looks very low.

Borys

Says "Total weight" so I presume that includes the mooring chain and auto setting hydrostat. Even if not, I somehow doubt the chain weighed 0.625t per mine.

As to the number of shells:

Ammunition stowage per gun    1907 to 1918
   Cruisers:  150 rounds (later increased to 183)
   G96 and V170 Destroyers:  80 rounds
   V25 Destroyers (as rearmed):  70 rounds
   B97 Destroyers (as rearmed):  80 rounds
   Submarines:  Between 100 and 250 rounds

1925 to 1945
   Möwe:  100 rounds
   Others:  N/A

So I went w/ the high end. Maybe this is another example of what we percieve as "Normal" being out of whack w/ RL examples, similar to the whole freeboard/seakeeping thing and the mine weight.

[Borys]

Ahoj!
Excellent info about the shells on GTBs.
I must have missed it :)
Looks like they had enough rounds for a c.8 minute firefight. Thinking about it - this low (?) ammo allocation is probably in line with German doctrine and practice of hit and run sorties.
I wonder how many shells the RN destroyers shipped?
Borys

[Guinness]

I've only got convenient data for two classes, but Friedman lists 120 rounds for both the S-Class (WW1) and the Leader Scott. I assume that is per gun. It seems the Brits decided after the war that wasn't enough, because the first interwar classes got 190 rounds (again I assume that's per gun).

I also wonder if those numbers for the Germans might only be magazine allocations, and if maybe they carried a few more rounds in addition to that in ready-use lockers. I have no actual evidence that might be true; it's just a hunch.

[Sachmle]

I could see that being magazine only, but w/ open deck mounts how many 105mm rounds can you store on deck nearby? 10-20 per gun maybe? It's not like they're insignificantly small.

[miketr]

10 or 20 is reasonable for ships that odds are wouldn't leave the North Sea / Baltic very often.  Also 10 or 20 would be a 1/8 to 1/4 increase in total ammo supply.

[Borys]

Ahoj!
Let us not forget that the German ships were "torpedo boats", while the RN ships were "destroyers of torpedo boats". So the main weapon was different. Thus I see substance to chose - depending upon a navy's doctrine - anything between 80 and 200 shells per gun.

Although I do not believe in ROF higher than 7-9 rpm for guns over 105mm, I think that if some sort of artillery duels are expected, then being able to fire for longer than 10 minutes seems essential.

Borys

[Sachmle]

I think one other thing to remember is that how often are GTBs firing all guns at once either on the broadside or at multiple targets? I see them firing the bow gun as they close on target and the stern gun as they run away after firing torpedoes. In this scenario I could see some shifting of ready use ammo from the midships mounts to the fore and aft mount if REALLY needed for prolonged gun duels. Remember, most GTBs either had NO hoists, or 1 per group of guns. So they're moving the shells to the guns from the magazine/hoist already, so does it really matter WHICH gun they take the ammo to?