Guns of Seneca Seagoing Monitor

[Delta Force]

Thoughts on this? The heavy armament is intended to be used for shore bombardment, in order to save the guns of the battleships from wear and tear. Also, this gun is intended to fire high explosive shells instead of armor piercing anyways.

Guns of Seneca, CSA Seagoing Monitor laid down 1920

Displacement:
   10,479 t light; 11,396 t standard; 12,560 t normal; 13,490 t full load

Dimensions: Length overall / water x beam x draught
   393.70 ft / 393.70 ft x 75.46 ft x 26.90 ft (normal load)
   120.00 m / 120.00 m x 23.00 m  x 8.20 m

Armament:
      2 - 18.00" / 457 mm guns in single mounts, 4,000.00lbs / 1,814.37kg shells, 1920 Model
     Breech loading guns in turrets (on barbettes)
     on centreline ends, evenly spread
   Weight of broadside 8,000 lbs / 3,629 kg
   Shells per gun, main battery: 150

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   10.0" / 254 mm   255.00 ft / 77.72 m   8.25 ft / 2.51 m
   Ends:   Unarmoured
     Main Belt covers 100 % of normal length

   - Torpedo Bulkhead:
      1.00" / 25 mm   255.00 ft / 77.72 m   16.50 ft / 5.03 m

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   12.0" / 305 mm   8.00" / 203 mm      12.0" / 305 mm

   - Armour deck: 5.00" / 127 mm, Conning tower: 12.00" / 305 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 12,723 shp / 9,491 Kw = 18.00 kts
   Range 12,000nm at 12.00 kts
   Bunker at max displacement = 2,094 tons

Complement:
   593 - 771

Cost:
   £2.461 million / $9.846 million

Distribution of weights at normal displacement:
   Armament: 729 tons, 5.8 %
   Armour: 3,911 tons, 31.1 %
      - Belts: 939 tons, 7.5 %
      - Torpedo bulkhead: 156 tons, 1.2 %
      - Armament: 759 tons, 6.0 %
      - Armour Deck: 1,918 tons, 15.3 %
      - Conning Tower: 140 tons, 1.1 %
   Machinery: 445 tons, 3.5 %
   Hull, fittings & equipment: 4,894 tons, 39.0 %
   Fuel, ammunition & stores: 2,081 tons, 16.6 %
   Miscellaneous weights: 500 tons, 4.0 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     17,638 lbs / 8,001 Kg = 6.0 x 18.0 " / 457 mm shells or 3.6 torpedoes
   Stability (Unstable if below 1.00): 1.08
   Metacentric height 3.8 ft / 1.2 m
   Roll period: 16.2 seconds
   Steadiness   - As gun platform (Average = 50 %): 75 %
         - Recoil effect (Restricted arc if above 1.00): 0.82
   Seaboat quality  (Average = 1.00): 1.50

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.550
   Length to Beam Ratio: 5.22 : 1
   'Natural speed' for length: 19.84 kts
   Power going to wave formation at top speed: 48 %
   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:      14.76 ft / 4.50 m
      - Forecastle (20 %):   14.76 ft / 4.50 m
      - Mid (50 %):      14.76 ft / 4.50 m
      - Quarterdeck (15 %):   14.76 ft / 4.50 m
      - Stern:      14.76 ft / 4.50 m
      - Average freeboard:   14.76 ft / 4.50 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 85.5 %
      - Above water (accommodation/working, high = better): 98.3 %
   Waterplane Area: 20,733 Square feet or 1,926 Square metres
   Displacement factor (Displacement / loading): 113 %
   Structure weight / hull surface area: 164 lbs/sq ft or 802 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.92
      - Longitudinal: 3.08
      - Overall: 1.03
   Hull space for machinery, storage, compartmentation is adequate
   Room for accommodation and workspaces is adequate
   Ship has slow, easy roll, a good, steady gun platform
   Good seaboat, rides out heavy weather easily

[Sachmle]

I think 18" is overkill for this mission, your 13.5" or 15" guns should be fine. Try something like HMS Abercrombie as an example.

[snip]

also for shore bombardment, she is drawing a little much to allow her to move in close for more accurate shooting

[TexanCowboy]

What the heck would he even need such a moniter for? What's he trying to collapse, the gates on the Dairen Canal? That's the only thing that would really need such a monster....and there are much cheaper ways to do it.

[Sachmle]

also for shore bombardment, she is drawing a little much to allow her to move in close for more accurate shooting

Fair enough, try these instead, only draw 10.5' of water.

[Delta Force]

What kind of draught is good? HMS Furious had 8 meters.

As for the size of the gun itself, it's intended to be used against sea fortifications. That, and the power of the shells is such that high accuracy is not really needed, since it can leave quite a large crater wherever it lands, and anything with enough draught to get close would be quite vulnerable to shore batteries, especially considering that such a ship would have to have very light armor.

[snip]

What kind of draught is good? HMS Furious had 8 meters.

As for the size of the gun itself, it's intended to be used against sea fortifications. That, and the power of the shells is such that high accuracy is not really needed, since it can leave quite a large crater wherever it lands, and anything with enough draught to get close would be quite vulnerable to shore batteries, especially considering that such a ship would have to have very light armor.

Draught depends on were you are looking for this to operate. Im not an expert on this sort of stuff, so I will leave that to people who know more then me. The reason why I say that it is to deep is because the RN had problems getting ships with BB sized draft in close for shore bombardment work off the Belgian coast in 1914. This lead to the monitors like the Abercrombie and Marshal Ney that have drafts less then half that of yours.

despite the power of a 18" shell, you still need to hit what you are aiming at. This in some cases requires getting close. In reality, like others have said, against fortifications a well placed 13.5" or 15" shell will be just a effective. You can get more of these guns onto a similar displacement, increasing the amount of damage that can be delt. Also against a harden position, a near miss is likely to do next to no damage, increasing the need for accuracy.

[Sachmle]

What kind of draught is good? HMS Furious had 8 meters.

HMS Furious wasn't a monitor, she was an abortion of a battlecruiser, classified as a Large Light Cruiser.

[snip]

HMS Furious wasn't a monitor, she was an abortion of a battlecruiser

One of the better descriptions I have heard of the type.

[TexanCowboy]

What kind of draught is good? HMS Furious had 8 meters.

As for the size of the gun itself, it's intended to be used against sea fortifications. That, and the power of the shells is such that high accuracy is not really needed, since it can leave quite a large crater wherever it lands, and anything with enough draught to get close would be quite vulnerable to shore batteries, especially considering that such a ship would have to have very light armor.

I've got a fairly extensive knowledge of the Gulf, so...if you want to operate there, I'd want to cut it down to at least 10-12 feet...maybe even lower.

[Delta Force]

What kind of draught is good? HMS Furious had 8 meters.

As for the size of the gun itself, it's intended to be used against sea fortifications. That, and the power of the shells is such that high accuracy is not really needed, since it can leave quite a large crater wherever it lands, and anything with enough draught to get close would be quite vulnerable to shore batteries, especially considering that such a ship would have to have very light armor.

I've got a fairly extensive knowledge of the Gulf, so...if you want to operate there, I'd want to cut it down to at least 10-12 feet...maybe even lower.

That sounds good. How would this do as a Pacific monitor though (that is what this design is intended for)? I made the ship large so that it could hold more fuel, have more seaworthiness, and carry more shells and armor. 8 knots top speed would doom a ship in the Ocean or force the fleet to go at a crawl, but isn't a liability in the Gulf region since distances are much smaller and the weather is better than the North Atlantic unless a hurricane rolls through.

[ctwaterman]

The 4000 Lbs Shell is way way out of proportion.... the Japanese 18/45 was a mere 3200 Lbs.   Your shell is 1100 Lbs heavier then the standard making it a super super super heavy Shell.

Charles

[Delta Force]

The 4000 Lbs Shell is way way out of proportion.... the Japanese 18/45 was a mere 3200 Lbs.   Your shell is 1100 Lbs heavier then the standard making it a super super super heavy Shell.

Charles

While Furious fired shells of around that weight, the HE round could be up to 4,000 pounds:

http://www.navweaps.com/Weapons/WNBR_18-40_mk1.htm

Since the HE round is intended as the main shell, I figured going with that weight would be the most accurate.

[Sachmle]

HE 8crh - 3,320 lbs. (1,506 kg)

Plus rule here, unofficial as it may be since I can't seem to find it, was always 20% over SpringSharp default was the upper limit for "SuperHeavy" shells. The SS default for 18" is 2,916.00lbs, so the upper is 3499.2lbs (probably round up to 3,500lbs).

[Logi]

What caliber is the gun? 50?