DD design concepts: Ottoman 1000tonner

[Guinness]

To test some of the conclusions I came to via research into OTL DD freeboard, etc., here's a prospective Ottoman 1000 tonner. To be clear: the Ottomans are unlikely to build this, but it seemed a useful exercise. Note that it essentially trades hull weight for machinery. 3 shafts as the machinery is direct drive, so props can't be geared down to economic speed.

DD Concept, Ottoman Empire Destroyer laid down 1920 (Engine 1916)

Displacement:
   1,000 t light; 1,037 t standard; 1,168 t normal; 1,272 t full load

Dimensions: Length overall / water x beam x draught
   290.35 ft / 288.71 ft x 27.89 ft x 9.76 ft (normal load)
   88.50 m / 88.00 m x 8.50 m  x 2.98 m

Armament:
      3 - 4.72" / 120 mm guns in single mounts, 50.00lbs / 22.68kg shells, 1920 Model
     Breech loading guns in deck mounts
     on centreline, evenly spread, all raised mounts
     Aft Main mounts separated by engine room
      2 - 1.57" / 40.0 mm guns in single mounts, 1.95lbs / 0.89kg shells, 1920 Model
     Anti-aircraft guns in deck mounts
     on side, all amidships, all raised mounts - superfiring
   Weight of broadside 154 lbs / 70 kg
   Shells per gun, main battery: 150
   4 - 21.0" / 533 mm above water torpedoes

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

   - Conning tower: 0.59" / 15 mm

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 3 shafts, 35,500 shp / 26,483 Kw = 32.72 kts
   Range 2,750nm at 15.00 kts
   Bunker at max displacement = 236 tons

Complement:
   99 - 129

Cost:
   £0.343 million / $1.370 million

Distribution of weights at normal displacement:
   Armament: 20 tons, 1.7 %
   Armour: 6 tons, 0.5 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 5 tons, 0.4 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 1 tons, 0.1 %
   Machinery: 664 tons, 56.8 %
   Hull, fittings & equipment: 252 tons, 21.6 %
   Fuel, ammunition & stores: 167 tons, 14.3 %
   Miscellaneous weights: 58 tons, 5.0 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     179 lbs / 81 Kg = 3.4 x 4.7 " / 120 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.08
   Metacentric height 0.9 ft / 0.3 m
   Roll period: 12.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 45 %
         - Recoil effect (Restricted arc if above 1.00): 0.23
   Seaboat quality  (Average = 1.00): 0.43

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.520
   Length to Beam Ratio: 10.35 : 1
   'Natural speed' for length: 16.99 kts
   Power going to wave formation at top speed: 73 %
   Trim (Max stability = 0, Max steadiness = 100): 95
   Bow angle (Positive = bow angles forward): 0.00 degrees
   Stern overhang: 1.64 ft / 0.50 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      17.39 ft / 5.30 m
      - Forecastle (17 %):   15.42 ft / 4.70 m
      - Mid (33 %):      14.44 ft / 4.40 m (7.87 ft / 2.40 m aft of break)
      - Quarterdeck (9 %):   7.87 ft / 2.40 m
      - Stern:      7.87 ft / 2.40 m
      - Average freeboard:   10.42 ft / 3.18 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 201.8 %
      - Above water (accommodation/working, high = better): 65.0 %
   Waterplane Area: 5,464 Square feet or 508 Square metres
   Displacement factor (Displacement / loading): 41 %
   Structure weight / hull surface area: 27 lbs/sq ft or 130 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 0.96
      - Overall: 0.53
   Hull space for machinery, storage, compartmentation is extremely poor
   Room for accommodation and workspaces is cramped
   Caution: Lacks seaworthiness - very limited seakeeping ability

Misc Weights (standard):
8t: 4 21" Torpedoes
25t: Fire control
1t: Depth Charges(4)
10t: Minesweeping Gear
6t: Mines
8t: Misc equipment and reserve

Misc Weights as minelayer:
4t: 2 21" Torpedoes
25t: Fire control
29t: 29 Mines

Range at Top Speed: 265nm, or 8.1 hours
Trialspeed: 34 knots

[miketr]

Interesting design.  It might be helpful if Guinness if you had any suggestion as to a reasonable seakeeping range for DD's?  Some idea as to what we should build for.

[Guinness]

That's sort of what I'm trying to explore here. I think that we need to readjust what we consider good and bad seakeeping for destroyers.

It seems that something on the order of 0.25 or so is the bottom of acceptable, and something on the order of 0.7 and above is very good. It's possible that the average for small lightly built TBs and DDs is half that of bigger ships, similar to hull strength. So maybe 0.5 is "average"?

I'm probably going to attack line drawings of post WW1 dds with a ruler over the next long weekend to see if that holds true.

[Borys]

Ahoj!

I'm probably going to attack line drawings of post WW1 dds with a ruler over the next long weekend to see if that holds true.

Yeah! Whip them good!
Borys