Bombardment ship

[Korpen]

Another design that is unlikely to ever be built, unless I decide to develop the gun.
The ship is armed with a L19 38cm howitzer, the 307mm gun simmed is used as that gives an accurate weight for the howitzer.

The Howitzer has a range of at least 17km, and could defeat the deck armour of all ships, as well as most forts. The main reason for developing a 38cm howitzer would be as a cost defence piece, this is just another application.

Misc. weight include a cruiser level FC, which is considered enough as the ship is not intended to engage anything while she is moving.



Storhammare, Kingdom Sealclubber laid down 1916
Barbette ship

Displacement:
   1 500 t light; 1 674 t standard; 1 835 t normal; 1 963 t full load

Dimensions: Length overall / water x beam x draught
   229,66 ft / 229,66 ft x 49,21 ft x 9,84 ft (normal load)
   70,00 m / 70,00 m x 15,00 m  x 3,00 m

Armament:
      1 - 12,09" / 307 mm guns in single mounts, 1 807,79lbs / 820,00kg shells, 1916 Model
     Breech loading gun in open barbette
     on centreline amidships, 1 raised gun
   Weight of broadside 1 808 lbs / 820 kg
   Shells per gun, main battery: 137


Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:         -            -         2,76" / 70 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 3 000 shp / 2 238 Kw = 15,82 kts
   Range 4 000nm at 12,00 kts
   Bunker at max displacement = 289 tons

Complement:
   139 - 182

Cost:
   £0,263 million / $1,053 million

Distribution of weights at normal displacement:
   Armament: 110 tons, 6,0 %
   Armour: 40 tons, 2,2 %
      - Belts: 0 tons, 0,0 %
      - Torpedo bulkhead: 0 tons, 0,0 %
      - Armament: 40 tons, 2,2 %
      - Armour Deck: 0 tons, 0,0 %
      - Conning Tower: 0 tons, 0,0 %
   Machinery: 112 tons, 6,1 %
   Hull, fittings & equipment: 1 118 tons, 60,9 %
   Fuel, ammunition & stores: 335 tons, 18,2 %
   Miscellaneous weights: 120 tons, 6,5 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     2 882 lbs / 1 307 Kg = 3,3 x 12,1 " / 307 mm shells or 1,2 torpedoes
   Stability (Unstable if below 1.00): 1,25
   Metacentric height 2,6 ft / 0,8 m
   Roll period: 12,9 seconds
   Steadiness   - As gun platform (Average = 50 %): 66 %
         - Recoil effect (Restricted arc if above 1.00): 0,59
   Seaboat quality  (Average = 1.00): 1,31

Hull form characteristics:
   Hull has raised forecastle, raised quarterdeck
   Block coefficient: 0,577
   Length to Beam Ratio: 4,67 : 1
   'Natural speed' for length: 15,15 kts
   Power going to wave formation at top speed: 54 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 0,00 degrees
   Stern overhang: 0,00 ft / 0,00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      17,72 ft / 5,40 m
      - Forecastle (20 %):   17,72 ft / 5,40 m (9,35 ft / 2,85 m aft of break)
      - Mid (50 %):      9,35 ft / 2,85 m
      - Quarterdeck (15 %):   17,72 ft / 5,40 m (9,35 ft / 2,85 m before break)
      - Stern:      17,72 ft / 5,40 m
      - Average freeboard:   12,28 ft / 3,74 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 77,4 %
      - Above water (accommodation/working, high = better): 103,7 %
   Waterplane Area: 8 093 Square feet or 752 Square metres
   Displacement factor (Displacement / loading): 145 %
   Structure weight / hull surface area: 104 lbs/sq ft or 507 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0,85
      - Longitudinal: 4,35
      - Overall: 1,00
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is adequate
   Good seaboat, rides out heavy weather easily

[The Rock Doctor]

Sealclubber?

Like the design, though.  Would be a useful little thing for supporting amphibious operations.

[mentat]

I like your Howitzer Barge - be interested to see a version with 2 medium sized Howitzers instead of 1 Monster.

Can't help thinking it would improve reload times a lot and be more practical vs. most targets - could you fit 2 x 8" or 9"?

[Jefgte]

IMO, in the design, the rangefinder & the funnel are really near.

Place the rangefinder on the forecastle bridge & the funnel at the actual range finder place.

...or built a bigger aft bridge...


;)

[Korpen]

I like your Howitzer Barge - be interested to see a version with 2 medium sized Howitzers instead of 1 Monster.

Can't help thinking it would improve reload times a lot and be more practical vs. most targets - could you fit 2 x 8" or 9"?

Without any problem, even the heaviest howitzers in that size range is only a bit over 20 tons each. In fact it could be replaced with two 305mm howitzers and have weigth to spare.

But one reason for the design is that I was thinking about developing a 38cm howitzer for cost defence, then a ships such as this would be a way to use such a gun for other purposes.

[Korpen]

IMO, in the design, the rangefinder & the funnel are really near.

Place the rangefinder on the forecastle bridge & the funnel at the actual range finder place.

...or built a bigger aft bridge...


;)

Not a problem, as the ship is not really intended to fire on the move.

[Kaiser Kirk]

One liability of the smaller weapons is that the largest horse drawn siege guns were, at least I've read, 9.4", which was reflected in the designs of earlier fortifications. So 8" and 9" weapons may not be as useful against coastal forts as the 12". Plus you would be more likely to be within range of shore based counterfire.

[Korpen]

One liability of the smaller weapons is that the largest horse drawn siege guns were, at least I've read, 9.4", which was reflected in the designs of earlier fortifications. So 8" and 9" weapons may not be as useful against coastal forts as the 12". Plus you would be more likely to be within range of shore based counterfire.

True about land forts, but most costal "forts" is not heavily armoured, for the very simple reason that there is less need for them to be. Hitting a cost defence gun is like trying to hit the left barrel in a twin turret on a battleship, a very, very small target. This, and the fact that fire from ships can be expected to be guns rather the howitzers, removes most of the need for the kind of heavy armoured cupolas one can see in land forts. So even lighter howitzers can be effective against costal forts, as long as the firing ship can come to a stop and drop anchor to get any form of accuracy. The accuracy of a howitzer on a ship that is moving is going to be horrendous.

[Kaiser Kirk]

Likely correct there. My reference point for coastal forts are some heavily concreted 16" emplacements and US Civil War era forts.  However, if you want to use the vessel to help unhinge the flank of a fortified line, it might still matter.