Guns of Seneca Seagoing Monitor

[ctwaterman]

Using our Tech Tree...

an 18/40 may be developed if you have the 1915 Gun Tech
an 18/45 may be developed using the 1921 Gun Tech
an 18/50 may be developed using the 1928 Gun Tech.

So its an 18/40

I agree that Instead of Putting 2x18" guns it would be better to put more 12"/12" or even 14" and 15" guns as even suppressing a Disapearing carriage gun would take more accuracy then out right blast power.

The Only Defensive installation I can think of that would require a APC Round of 18" to disable right now are the two Heavy Gun Batteries covering the Harbor at Djibouti [France]  They have the Super Heavy Armor Option and are built into a Casement into the side of a mountain.   Everything is bigger and more expensive in France.... ::)

[Logi]

For a 18"/40 gun, the shell would be ~94" long.

That's roughly 5.2 cal? I don't remember the exact rule of thumb but it would appear at first glance that there won't be enough rifling.

[snip]

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.

In all honesty, at this time period, I see the concept of the monitor to be restricted to rivers and other very sheltered bodies of water. These are ships that are mounting BB caliber guns, so why not make them into a proper BB? Chances are that they would get pressed into fighting BBs due to there armament, but in that fight I would take the BB, even a predread any day.I guess what my question is, what can this do that a BB built on the same tonnage cannot? Why do you need a dedicated shore bombardment ship for cross-ocean work when a BB could do the job and more?

[Delta Force]

Well, I have a design for a fast battleship with six 18 inch guns:

CSA Battlecruiser, CSA Battlecruiser laid down 1920

Displacement:
   40,263 t light; 43,216 t standard; 49,222 t normal; 54,027 t full load

Dimensions: Length overall / water x beam x draught
   872.70 ft / 872.70 ft x 105.32 ft (Bulges 115.16 ft) x 31.17 ft (normal load)
   266.00 m / 266.00 m x 32.10 m (Bulges 35.10 m)  x 9.50 m

Armament:
      6 - 18.00" / 457 mm guns (3x2 guns), 3,500.00lbs / 1,587.57kg shells, 1920 Model
     Breech loading guns in turrets (on barbettes)
     on centreline ends, majority forward, 1 raised mount - superfiring
      16 - 5.50" / 140 mm guns (8x2 guns), 75.00lbs / 34.02kg shells, 1920 Model
     Breech loading guns in deck mounts with hoists
     on side ends, evenly spread
      4 - 1.58" / 40.0 mm guns in single mounts, 2.00lbs / 0.91kg shells, 1920 Model
     Anti-aircraft guns in deck mounts
     on centreline ends, evenly spread, all raised mounts - superfiring
   Weight of broadside 22,208 lbs / 10,073 kg
   Shells per gun, main battery: 158

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   14.0" / 356 mm   580.00 ft / 176.78 m   16.50 ft / 5.03 m
   Ends:   Unarmoured
     Main Belt covers 102 % of normal length

   - Torpedo Bulkhead and Bulges:
      1.00" / 25 mm   580.00 ft / 176.78 m   24.75 ft / 7.54 m

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   14.0" / 356 mm   8.00" / 203 mm      14.0" / 356 mm
   2nd:   6.00" / 152 mm   3.00" / 76 mm      6.00" / 152 mm

   - Armour deck: 4.00" / 102 mm, Conning tower: 14.00" / 356 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 4 shafts, 84,506 shp / 63,042 Kw = 25.30 kts
   Range 26,000nm at 12.00 kts
   Bunker at max displacement = 10,811 tons

Complement:
   1,652 - 2,148

Cost:
   £8.983 million / $35.932 million

Distribution of weights at normal displacement:
   Armament: 2,354 tons, 4.8 %
   Armour: 14,636 tons, 29.7 %
      - Belts: 5,666 tons, 11.5 %
      - Torpedo bulkhead: 531 tons, 1.1 %
      - Armament: 3,288 tons, 6.7 %
      - Armour Deck: 4,747 tons, 9.6 %
      - Conning Tower: 405 tons, 0.8 %
   Machinery: 2,955 tons, 6.0 %
   Hull, fittings & equipment: 19,917 tons, 40.5 %
   Fuel, ammunition & stores: 8,960 tons, 18.2 %
   Miscellaneous weights: 400 tons, 0.8 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     83,292 lbs / 37,780 Kg = 28.6 x 18.0 " / 457 mm shells or 12.6 torpedoes
   Stability (Unstable if below 1.00): 1.19
   Metacentric height 7.4 ft / 2.3 m
   Roll period: 17.7 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.60
   Seaboat quality  (Average = 1.00): 1.33

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.550
   Length to Beam Ratio: 7.58 : 1
   'Natural speed' for length: 29.54 kts
   Power going to wave formation at top speed: 39 %
   Trim (Max stability = 0, Max steadiness = 100): 53
   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:      22.47 ft / 6.85 m
      - Forecastle (20 %):   22.47 ft / 6.85 m
      - Mid (50 %):      22.47 ft / 6.85 m
      - Quarterdeck (15 %):   22.47 ft / 6.85 m
      - Stern:      22.47 ft / 6.85 m
      - Average freeboard:   22.47 ft / 6.85 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 72.8 %
      - Above water (accommodation/working, high = better): 166.2 %
   Waterplane Area: 64,142 Square feet or 5,959 Square metres
   Displacement factor (Displacement / loading): 124 %
   Structure weight / hull surface area: 218 lbs/sq ft or 1,063 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.99
      - Longitudinal: 1.08
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is excellent
   Ship has slow, easy roll, a good, steady gun platform
   Good seaboat, rides out heavy weather easily

[TexanCowboy]

It's a scary day when my next battleships are able to outrun a battlecruiser.

If you look in the Nassau boards, while I was there, I posted some nice designs for a fast battleship that you might be interested in.

[Sachmle]

And 18/40 will not get you much appreciable advantage over a 16/45 or a 15/50, IMHO. Yes the shell is bigger, but you lose a lot due to longer reloading time, slower firing, and with only being able to fit 6 guns, crappy spotting compared to an 8 gun 15-16" variety. Also, your paper thin TDS will do nothing to stop a torpedo, and will likely just add shrapnel to the explosion. Other than that, quite nice. I do recommend getting light displacement to an even value (40,250- 40,000- 40,500, etc) just for ease of bookkeeping. I also don't think the CSA has any type 4 slips/docks, thought one could be built at Hampton Roads/Newport News as it is a type 4 port. That is a lot of infrastructure though. You'd need a dry dock, or you'd not be able to repair/refit the ship, and those cost $27 and 4BP and would take ~2.5 years to build. SO if you started the dry dock in 2/19 (Last report was 1/19 by Carth) you could have it in 1/22. Then it takes 4.5yrs to build this thing, so it would be ready for trails in 2/26, with trails ending at the end of August 1926 and in service September 1926. IS this a valid design by then? Will BBs be 28kts by then? I think you'll find, as most of us did (why we did the Richmond Treaty) that 35,000t is about as big as you want to get until tech stabilizes in the 1930s. Until then, things change to much between lay down and in service.

[TexanCowboy]

CSA has a Type 4 DD at Charleston.

[Sachmle]

CSA has a Type 4 DD at Charleston.

at Charleston Naval Station, South Carolina; Type 3 Harbor
- Charleston Navy Yard
Type 3 Drydocks - 2
Type 2 Drydocks - 2
Type 1 Drydocks - 1
Type 1 Slip - 1
http://www.navalism.org/index.php?topic=3927.0

[TexanCowboy]

Well, you see, it got done in 1918, and with all the chaos regarding Carth's return, it never got posted. You can look it up in the sim reports...

[Sachmle]

Well, you see, it got done in 1918, and with all the chaos regarding Carth's return, it never got posted. You can look it up in the sim reports...

I did, the Port upgrade got completed, no one ever started the dry dock though.

[Delta Force]

Thoughts on this? It takes only a year to complete. I tried to make a design that could fit into a size 2 dock, but most of those designs ended up weighing around 7k to 8k tons, so I decided to just make the design larger to allow it to fit more guns. The same design can also fit two 16 or two 18 inch guns, or six 12 inch guns (although the CSA has no modern 12 inch guns).

Guns of Seneca, CSA Littoral Bombardment Ship laid down 1920

Displacement:
   12,000 t light; 12,558 t standard; 13,016 t normal; 13,383 t full load

Dimensions: Length overall / water x beam x draught
   459.32 ft / 459.32 ft x 120.87 ft x 11.98 ft (normal load)
   140.00 m / 140.00 m x 36.84 m  x 3.65 m

Armament:
      4 - 13.50" / 343 mm guns (2x2 guns), 1,500.00lbs / 680.39kg shells, 1920 Model
     Breech loading guns in turrets (on barbettes)
     on centreline ends, evenly spread
      8 - 4.85" / 123 mm guns (4x2 guns), 55.00lbs / 24.95kg shells, 1920 Model
     Breech loading guns in deck mounts with hoists
     on side, all amidships
   Weight of broadside 6,440 lbs / 2,921 kg
   Shells per gun, main battery: 82

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   8.00" / 203 mm   330.00 ft / 100.58 m   8.25 ft / 2.51 m
   Ends:   Unarmoured
     Main Belt covers 111 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   10.0" / 254 mm   6.00" / 152 mm      10.0" / 254 mm
   2nd:   6.00" / 152 mm   3.00" / 76 mm      6.00" / 152 mm

   - Armour deck: 2.00" / 51 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 1,040 shp / 776 Kw = 8.00 kts
   Range 8,000nm at 8.00 kts
   Bunker at max displacement = 825 tons

Complement:
   609 - 792

Cost:
   £2.339 million / $9.357 million

Distribution of weights at normal displacement:
   Armament: 672 tons, 5.2 %
   Armour: 3,496 tons, 26.9 %
      - Belts: 987 tons, 7.6 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 884 tons, 6.8 %
      - Armour Deck: 1,625 tons, 12.5 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 36 tons, 0.3 %
   Hull, fittings & equipment: 7,420 tons, 57.0 %
   Fuel, ammunition & stores: 1,016 tons, 7.8 %
   Miscellaneous weights: 375 tons, 2.9 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     45,324 lbs / 20,559 Kg = 36.8 x 13.5 " / 343 mm shells or 7.7 torpedoes
   Stability (Unstable if below 1.00): 1.47
   Metacentric height 12.9 ft / 3.9 m
   Roll period: 14.1 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.12
   Seaboat quality  (Average = 1.00): 1.07

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.685
   Length to Beam Ratio: 3.80 : 1
   'Natural speed' for length: 21.43 kts
   Power going to wave formation at top speed: 11 %
   Trim (Max stability = 0, Max steadiness = 100): 65
   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:      15.75 ft / 4.80 m
      - Forecastle (20 %):   15.75 ft / 4.80 m
      - Mid (50 %):      15.75 ft / 4.80 m
      - Quarterdeck (15 %):   15.75 ft / 4.80 m
      - Stern:      15.75 ft / 4.80 m
      - Average freeboard:   15.75 ft / 4.80 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 43.7 %
      - Above water (accommodation/working, high = better): 216.3 %
   Waterplane Area: 43,913 Square feet or 4,080 Square metres
   Displacement factor (Displacement / loading): 140 %
   Structure weight / hull surface area: 157 lbs/sq ft or 767 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.95
      - Longitudinal: 1.60
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is excellent
   Ship has slow, easy roll, a good, steady gun platform

[snip]

I still question the need for such a ship, mainly when the CSA has several early Dreadnaughts that displace only a bit more than this and have 2 more guns, faster, and better armored. Why do you need a dedicated bombardment ships when a BB can do that same job and much more on a similar displacement?

[Delta Force]

This ship has a draught of 12 feet (compared to 22 feet for older battleships), so it can get much closer to shore for precision fire. That said, I might delete one of the turrets in order to add in provision for troop carriage, to make it something of a troop landing ship. That would allow it to take more advantage of its draught and perform another role for the fleet.

[ctwaterman]

Completion time is 9 Months + Tonnage/1000

[snip]

On the concept:
You have a valid point on the draft issue. However IMO, sending something this big very close into a beach creates one heck of an shell magnet for land-based guns. With this ships (and the other designs presented) questionably thin armor, I don't think it would last to long under heavy fire from battleship caliber guns to get into optimum range for destroying those positions. Also the speed of 8-18knts makes it possible for almost any warship to force a confrontation, which could be done in places with not a lot of room to maneuver due to these ships being so large, making torpedo even more dangerous. With no torpedo bulkhead, this ship could find itself in trouble very fast. In all honesty, I think that close-support ships need to be small and expendable above all else. I think there is a reason why BBs were the typical shore bombardment ships in OTL, and not big-gun ships tailor made for the roll. While tactically it may seem like a good idea (and this is an asset that I'm sure the boots hitting the beach would love), its to big of an asset to risk when it is looked at in a logistical or strategic manor. Whats cheaper and takes less time, relining guns or replacing one or two of these? How much more could two "conventional" multi-roll ships (raiders, Heavy cruisers ect.) on the same tonnage change the strategic picture?

On the design itself:
Few little issues that I see with the design. First:

Length to Beam Ratio: 3.80 : 1

Little to small. From my understanding, 5:1 is about as low as you can get. Someone with more experience may correct me on this. Second:

Hull, fittings & equipment: 7,420 tons, 57.0 %

This means that 57% of the displacement has nothing to do with armor, guns, or speed. By comparison, most of the BBs that I have seen have about 35-40% for this category, and I have seen one example around 30%. It should be possible to get much more bang-for-the-buck out of this hull.