Torpedo-boat mothership

[Valles]

A specialist take on the concept this time, rather than a hybrid. This design is intended to field a maximum number of boats at a minimum of cost. The motherships themselves can neither run nor fight anything larger than a motorboat; if caught without escorts, their crews would abandon ship and scuttle them rather than waste lives and energy trying to fight a real warship. They are unambiguously support vessels, albeit ones designed to keep pace with the main fleet.

Enter ship name, Enter country Enter ship type laid down 1912

Displacement:
   4,018 t light; 4,165 t standard; 7,000 t normal; 9,268 t full load

Dimensions: Length overall / water x beam x draught
   369.18 ft / 360.89 ft x 45.93 ft x 16.40 ft (normal load)
   112.52 m / 110.00 m x 14.00 m  x 5.00 m

Armament:
      6 - 2.95" / 75.0 mm guns in single mounts, 13.23lbs / 6.00kg shells, 1912 Model
     Quick firing guns in deck mounts
     on side, evenly spread
   Weight of broadside 79 lbs / 36 kg
   Shells per gun, main battery: 150

Machinery:
   Oil fired boilers, steam turbines,
   Electric motors, 1 shaft, 22,202 shp / 16,563 Kw = 22.00 kts
   Range 20,000nm at 14.00 kts
   Bunker at max displacement = 5,103 tons

Complement:
   382 - 497

Cost:
   £0.273 million / $1.091 million

Distribution of weights at normal displacement:
   Armament: 10 tons, 0.1 %
   Machinery: 885 tons, 12.6 %
   Hull, fittings & equipment: 1,523 tons, 21.8 %
   Fuel, ammunition & stores: 2,982 tons, 42.6 %
   Miscellaneous weights: 1,600 tons, 22.9 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     11,186 lbs / 5,074 Kg = 869.0 x 3.0 " / 75 mm shells or 1.8 torpedoes
   Stability (Unstable if below 1.00): 1.10
   Metacentric height 1.9 ft / 0.6 m
   Roll period: 14.1 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.02
   Seaboat quality  (Average = 1.00): 1.19

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.901
   Length to Beam Ratio: 7.86 : 1
   'Natural speed' for length: 19.00 kts
   Power going to wave formation at top speed: 62 %
   Trim (Max stability = 0, Max steadiness = 100): 59
   Bow angle (Positive = bow angles forward): 5.00 degrees
   Stern overhang: 6.56 ft / 2.00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      19.69 ft / 6.00 m
      - Forecastle (20 %):   16.40 ft / 5.00 m
      - Mid (50 %):      16.40 ft / 5.00 m
      - Quarterdeck (15 %):   16.40 ft / 5.00 m
      - Stern:      16.40 ft / 5.00 m
      - Average freeboard:   16.67 ft / 5.08 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 67.8 %
      - Above water (accommodation/working, high = better): 130.8 %
   Waterplane Area: 15,997 Square feet or 1,486 Square metres
   Displacement factor (Displacement / loading): 203 %
   Structure weight / hull surface area: 63 lbs/sq ft or 308 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.94
      - Longitudinal: 1.70
      - 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

700 tons boat support equipment (merchant standards)
7x 100 tons torpedo boats (laminated wood construction)
25 tons long-range wireless
25 tons small hospital
150 tons torpedoes and other supplies

557 ton-equivalents of merchant-standard construction
1084 tons military-standard equipment
350 ton-equivalents of wooden-hull construction

Total 1991 ton-equivalents - $2, 2BP

[The Rock Doctor]

By "mothership", do you mean a conventional tender, or do you mean a TB carrier?

[Valles]

Full carrier, with an aft ramp, enclosed 'hanger deck' and integral cranes.

[The Rock Doctor]

A sketch would be helpful.

[Korpen]

Full carrier, with an aft ramp, enclosed 'hanger deck' and integral cranes.

Considred having a internal dock for a ship or two like on Caio Duilio?
http://www.steelnavy.com/DelphisCDuilio.htm

[Valles]

Passage, Maori Torpedoboat Mothership laid down 1912

Displacement:
   4,082 t light; 4,225 t standard; 6,908 t normal; 9,055 t full load

Dimensions: Length overall / water x beam x draught
   362.90 ft / 360.89 ft x 45.93 ft x 19.69 ft (normal load)
   110.61 m / 110.00 m x 14.00 m  x 6.00 m

Armament:
      4 - 2.95" / 75.0 mm guns in single mounts, 13.23lbs / 6.00kg shells, 1912 Model
     Quick firing guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 53 lbs / 24 kg
   Shells per gun, main battery: 150

Machinery:
   Oil fired boilers, steam turbines,
   Electric motors, 1 shaft, 20,603 shp / 15,370 Kw = 22.00 kts
   Range 20,000nm at 14.00 kts
   Bunker at max displacement = 4,831 tons

Complement:
   378 - 492

Cost:
   £0.263 million / $1.053 million

Distribution of weights at normal displacement:
   Armament: 6 tons, 0.1 %
   Machinery: 822 tons, 11.9 %
   Hull, fittings & equipment: 1,854 tons, 26.8 %
   Fuel, ammunition & stores: 2,826 tons, 40.9 %
   Miscellaneous weights: 1,400 tons, 20.3 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     12,399 lbs / 5,624 Kg = 963.3 x 3.0 " / 75 mm shells or 2.1 torpedoes
   Stability (Unstable if below 1.00): 1.11
   Metacentric height 1.9 ft / 0.6 m
   Roll period: 14.0 seconds
   Steadiness   - As gun platform (Average = 50 %): 80 %
         - Recoil effect (Restricted arc if above 1.00): 0.03
   Seaboat quality  (Average = 1.00): 1.81

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.741
   Length to Beam Ratio: 7.86 : 1
   'Natural speed' for length: 19.00 kts
   Power going to wave formation at top speed: 60 %
   Trim (Max stability = 0, Max steadiness = 100): 44
   Bow angle (Positive = bow angles forward): 5.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      22.97 ft / 7.00 m
      - Forecastle (20 %):   19.69 ft / 6.00 m
      - Mid (50 %):      19.69 ft / 6.00 m
      - Quarterdeck (15 %):   19.69 ft / 6.00 m
      - Stern:      19.69 ft / 6.00 m
      - Average freeboard:   19.95 ft / 6.08 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 62.3 %
      - Above water (accommodation/working, high = better): 136.5 %
   Waterplane Area: 13,760 Square feet or 1,278 Square metres
   Displacement factor (Displacement / loading): 223 %
   Structure weight / hull surface area: 73 lbs/sq ft or 356 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 1.00
      - Longitudinal: 3.65
      - Overall: 1.13
   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
   Excellent seaboat, comfortable, can fire her guns in the heaviest weather

600 tons boat support equipment (merchant standards)
6x 100 tons torpedo boats (laminated wood construction)
25 tons long-range wireless
25 tons small hospital
350 tons torpedoes and other supplies

557 ton-equivalents of merchant-standard construction
1,084 tons military-standard equipment
350 ton-equivalents of wooden-hull construction

Total 1,991 ton-equivalents - $2, 2BP

...I think I may have muffed the math there a touch, but anyway you get the idea. Once I knew that centerline well decks were allowed under the rules, there was no question but that the docking would be internal. Aside from the derricks, there are two cranes integrated into the 'roof' of the hanger to lift torpedoes, turbines, or other replacement parts for the TBs through the (flush, sealable) hatches in the hanger floor.

ETA: Okay, revised version with increased beam and working space and sketched-in blocking for machinery spaces, boiler, turbines, generator/bus move from fore to aft. The forward flush hatch has been replaced by twin accesses to the forward hold to make more room for machinery.

[Jefgte]

Better concept than the French "La Foudre"

Did you made the SS for the Torpedo boats?


Jef  ;)

[Sachmle]

Is there any precident for a ship like this in this time frame? Or ever? Not trying to rain on anyone's parade, but she seems a little advanced. Why not just convert a merchant w/ large holds and pre-installed cranes to carry TBs? It's not like you'll be able to deploy the TBs under fire anyway. It's basically a transport.

[Valles]

Did you made the SS for the Torpedo boats?

I haven't and don't see a point. TBs are nearly pure planing craft. SS's speed/power model is pure displacement. Getting even the most nominal guess of their real capabilities out of it is impossible. I have, in the past, proposed and requested a development tech for small planing boats along the lines of the one used for submarines.

Since nothing's come of that, I've taken the admittedly slightly dodgy course of just assuming that the Maori Admiralty were able to get what they asked for when they handed their design requirements to the private sector.

In this case, that means that Maori TBs are were developed from motor life boats - that is, enclosed everywhere except the aft gun platform and as close to storm-proof as something their size can be, with sealed compartments along the hull and a weighted keel. They're good for thirty knots in most weathers, they carry a single 75mm aft and two torpedoes fixed forwards. Their range at speed is probably no more than a hundred, hundred-fifty nautical miles; they're intended to be deployed when an enemy comes over the horizon.

Doctrine for their use is to favor night attacks; they're steam-powered and thus mostly silent. If used in daytime they'd be making their strikes against targets being shelled by the main battle-line. Either way, maximum release range is 1000m. Hit rates outside that range are bad enough that you might as well have stayed home, in the Admiralty's view.

Is there any precident for a ship like this in this time frame? Or ever? Not trying to rain on anyone's parade, but she seems a little advanced. Why not just convert a merchant w/ large holds and pre-installed cranes to carry TBs? It's not like you'll be able to deploy the TBs under fire anyway. It's basically a transport.

I believe that my views on precedent are well established.

However, in this case, there are similar ships already in the water.

http://www.navalism.org/index.php?topic=337.0

[Sachmle]

Fair enough. I don't have a problem w/ it personnaly, it's just kinda like Tan and Carth's experimental aircraft carriers, and I think we're all alittle ahead of things on one aspect or another. But this is Nverse, not Earth, so maybe we're not ahead, but right on schedule.  ;D

[The Rock Doctor]

There's precedent for it, and it's not yet constrained by rules, but that doesn't necessarily mean it ought to be in use.  Are folks generally satisifed that allocating 1 t of equipment for each ton of docked stuff is an acceptable means of simming a well deck?

An MTB tech would a good thing, but the Mods don't necessarily have time to compile it.  If somebody wants to take the initiative and propose something, I'm all ears.

From the design perspective - doctrine aside, I don't think it's practical to have the funnel and machinery that far forward on the ship.  I think most ships with a well-deck only use a third to a half of the internal length for the purpose.

[P3D]

Blame Maddox on the idea, he invented TB carriers in Nverse (to be exact, it was the late Agrival Mars).

To limit hindsight, my ship does not have a proper well deck. It also means that amphibious 'motherships' will appear like 25 years in advance.

I'd note that there's hardly any space to move around the boats. Increase beam - then there'd be space for an amidships funnel.

[Valles]

I've edited my 'art included' post with an updated version.

Also, I've already posted a tentative suggestion of a TB boat tech the thread about it in General; it didn't generate much comment.

The other idea I've had is for a fairly complicated 'point buy' system, where the tech grants 'X design points' per given level, which can then be multiplied by some factor related to tonnage or engine tech and used to buy speed, seakeeping, payload, and other characteristics desired.

[The Rock Doctor]

I must have overlooked that.  I'll go looking for it.