Are we overdesigning destroyers?

[Guinness]

I'm not going to kill myself on this, since the essential question was about seakeeping. The ship did indeed have a twin mounting forward, and 3 singles aft. I was shooting for her condition around the time the twin forward was finally fitted.

Here she is with the transom stern fitted (I forgot all abut that!), but otherwise more or less the same. For endurance I used the cited figure. SS's machinery weights and bunkerage are bound to be different, maybe vastly different than in real life.

Type 1936a, Germany Destroyer laid down 1938 (Engine 1940)

Displacement:
   3,238 t light; 3,365 t standard; 3,605 t normal; 3,797 t full load

Dimensions: Length overall / water x beam x draught
   416.68 ft / 399.93 ft x 39.37 ft x 15.26 ft (normal load)
   127.00 m / 121.90 m x 12.00 m  x 4.65 m

Armament:
      5 - 5.87" / 149 mm guns (4 mounts), 99.87lbs / 45.30kg shells, 1938 Model
     Breech loading guns in deck mounts with hoists
     on centreline ends, evenly spread, 2 raised mounts - superfiring
      4 - 1.46" / 37.0 mm guns in single mounts, 1.63lbs / 0.74kg shells, 1938 Model
     Anti-aircraft guns in deck mounts with hoists
     on side, all amidships, all raised mounts - superfiring
      12 - 0.79" / 20.0 mm guns in single mounts, 0.29lbs / 0.13kg shells, 1938 Model
     Anti-aircraft guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 509 lbs / 231 kg
   Shells per gun, main battery: 190
   8 - 21.0" / 533 mm above water torpedoes

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 70,000 shp / 52,220 Kw = 35.30 kts
   Range 2,174nm at 19.00 kts
   Bunker at max displacement = 432 tons

Complement:
   232 - 302

Cost:
   £2.350 million / $9.402 million

Distribution of weights at normal displacement:
   Armament: 64 tons, 1.8 %
   Machinery: 1,783 tons, 49.5 %
   Hull, fittings & equipment: 1,360 tons, 37.7 %
   Fuel, ammunition & stores: 367 tons, 10.2 %
   Miscellaneous weights: 30 tons, 0.8 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     1,268 lbs / 575 Kg = 12.5 x 5.9 " / 149 mm shells or 0.4 torpedoes
   Stability (Unstable if below 1.00): 1.00
   Metacentric height 1.2 ft / 0.4 m
   Roll period: 14.9 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.51
   Seaboat quality  (Average = 1.00): 0.53

Hull form characteristics:
   Hull has rise forward of midbreak
     and transom stern
   Block coefficient: 0.525
   Length to Beam Ratio: 10.16 : 1
   'Natural speed' for length: 22.73 kts
   Power going to wave formation at top speed: 71 %
   Trim (Max stability = 0, Max steadiness = 100): 93
   Bow angle (Positive = bow angles forward): 27.25 degrees
   Stern overhang: 5.09 ft / 1.55 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      22.64 ft / 6.90 m
      - Forecastle (15 %):   19.69 ft / 6.00 m
      - Mid (38 %):      18.04 ft / 5.50 m (10.76 ft / 3.28 m aft of break)
      - Quarterdeck (12 %):   10.76 ft / 3.28 m
      - Stern:      11.81 ft / 3.60 m
      - Average freeboard:   14.24 ft / 4.34 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 174.7 %
      - Above water (accommodation/working, high = better): 79.7 %
   Waterplane Area: 11,170 Square feet or 1,038 Square metres
   Displacement factor (Displacement / loading): 84 %
   Structure weight / hull surface area: 72 lbs/sq ft or 353 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.94
      - Longitudinal: 1.76
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is cramped
   Caution: Lacks seaworthiness - very limited seakeeping ability

[Sachmle]

For the hell of it I compiled a list of the varying stats for these ship as found on different sites.

	Wikipedia	German-navy	Warship WWII	Navypedia
Length WL	?	121.9	121.9	121.9
Length OA	127	127	127	127
Beam	12	12	12	12
Draft Norm	?	?	3.7-3.92	3.92
Draft Max	4.65	4.65	4.65	4.62
Standard	2600	?	2603-3079	2543-2657
Full	3605	3605	3519-3605	3519-3691
Speed	37.5	37.5	36-37	36
Range	2150 @ 18	2174 @ 19	2087-2239 @19	?

[Guinness]

That helps: draft was way too deep, as I thought the figure I had was normal or standard, not full load.

Type 1936a, Germany Destroyer laid down 1938

Displacement:
   2,434 t light; 2,544 t standard; 2,748 t normal; 2,911 t full load

Dimensions: Length overall / water x beam x draught
   416.68 ft / 399.93 ft x 39.37 ft x 12.86 ft (normal load)
   127.00 m / 121.90 m x 12.00 m  x 3.92 m

Armament:
      5 - 5.87" / 149 mm guns (4 mounts), 99.87lbs / 45.30kg shells, 1938 Model
     Breech loading guns in deck mounts with hoists
     on centreline ends, evenly spread, 2 raised mounts - superfiring
      4 - 1.46" / 37.0 mm guns in single mounts, 1.63lbs / 0.74kg shells, 1938 Model
     Anti-aircraft guns in deck mounts with hoists
     on side, all amidships, all raised mounts - superfiring
      12 - 0.79" / 20.0 mm guns in single mounts, 0.29lbs / 0.13kg shells, 1938 Model
     Anti-aircraft guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 509 lbs / 231 kg
   Shells per gun, main battery: 190
   8 - 21.0" / 533 mm above water torpedoes

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 70,000 shp / 52,220 Kw = 37.06 kts
   Range 2,174nm at 19.00 kts
   Bunker at max displacement = 367 tons

Complement:
   189 - 246

Cost:
   £1.999 million / $7.995 million

Distribution of weights at normal displacement:
   Armament: 64 tons, 2.3 %
   Machinery: 1,538 tons, 56.0 %
   Hull, fittings & equipment: 702 tons, 25.5 %
   Fuel, ammunition & stores: 314 tons, 11.4 %
   Miscellaneous weights: 130 tons, 4.7 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     461 lbs / 209 Kg = 4.6 x 5.9 " / 149 mm shells or 0.3 torpedoes
   Stability (Unstable if below 1.00): 1.10
   Metacentric height 1.5 ft / 0.4 m
   Roll period: 13.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.51
   Seaboat quality  (Average = 1.00): 0.55

Hull form characteristics:
   Hull has rise forward of midbreak
     and transom stern
   Block coefficient: 0.475
   Length to Beam Ratio: 10.16 : 1
   'Natural speed' for length: 22.86 kts
   Power going to wave formation at top speed: 71 %
   Trim (Max stability = 0, Max steadiness = 100): 90
   Bow angle (Positive = bow angles forward): 27.25 degrees
   Stern overhang: 5.09 ft / 1.55 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      22.64 ft / 6.90 m
      - Forecastle (15 %):   19.69 ft / 6.00 m
      - Mid (38 %):      18.04 ft / 5.50 m (10.76 ft / 3.28 m aft of break)
      - Quarterdeck (12 %):   10.76 ft / 3.28 m
      - Stern:      11.81 ft / 3.60 m
      - Average freeboard:   14.24 ft / 4.34 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 203.9 %
      - Above water (accommodation/working, high = better): 93.4 %
   Waterplane Area: 10,662 Square feet or 991 Square metres
   Displacement factor (Displacement / loading): 61 %
   Structure weight / hull surface area: 40 lbs/sq ft or 196 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 0.97
      - Overall: 0.54
   Hull space for machinery, storage, compartmentation is extremely poor
   Room for accommodation and workspaces is adequate
   Caution: Lacks seaworthiness - very limited seakeeping ability

[Guinness]

Brown also discusses seakeeping in his section on Destroyers, p.98 and 99. There he explicitly lists freeboard as being freeboard at the bow, but in what condition I don't know. Going by his numbers, it may be full load or at least standard. He also includes the bridge location as a ratio of length. He notes that the Tribals were considered better seaboats mainly because their bridge was further from the bow, but that consequently they tended to be driven hard, and were still considered wet.

At any rate, he includes this great table:

Freeboard ratios and bridge abaft bow (fraction of length)

Ship	Length(ft)	Fboard(ft)	1.1sqrt(Lwl)	Bridge
'V&W'	300	18.8	17.3	0.29
'I' Class	320	16.8	17.9	0.29
'Tribal'	364.7	18.2	19.1	0.34
Javelin	348	19.7	18.6	0.29
Fubuki	378	20.8	19.4	0.23
Z-23(5.9in Guns)	400	21.5	22	0.24
Fletcher	376	19.5	19.4	0.28
Le Triomphant	420	22.9	20.5	0.25

[Guinness]

I knew I'd read this somewhere before. From the SS2 documentation:

Ships with a freeboard at Box 13 lower than 1.1 x the square root of the length (D.K. Brown – RN Rule of thumb in WWII) will be considered wet forward. This is not a design failure as most ships in the 19th and early 20th centuries were wet forward.

So if we followed this guideline, we'd never have "wet forward" notes. Still, I believe that for small fast ships, this metric is much more important than the overall SS seakeeping value.