Logi's Design Studies

[Logi]

APA: All 449t of misc. weight is devoted to carrying short-ranged landing craft meaning the boat carries 1796 troops.

Jap-Gig, RRC Attack Class laid down 1915 (Engine 1912)

Displacement:
   2,916 t light; 3,048 t standard; 3,546 t normal; 3,945 t full load

Dimensions: Length overall / water x beam x draught
   455.00 ft / 455.00 ft x 62.00 ft x 8.00 ft (normal load)
   138.68 m / 138.68 m x 18.90 m  x 2.44 m

Armament:
      2 - 6.00" / 152 mm guns (1x2 guns), 108.00lbs / 48.99kg shells, 1915 Model
     Breech loading guns in a deck mount with hoist
     on centreline forward
      4 - 6.00" / 152 mm guns (2x2 guns), 108.00lbs / 48.99kg shells, 1915 Model
     Breech loading guns in deck mounts with hoists
     on side, all forward
      8 - 0.50" / 12.7 mm guns (4x2 guns), 0.06lbs / 0.03kg shells, 1915 Model
     Machine guns in deck mounts
     on side, all amidships
      4 - 0.50" / 12.7 mm guns (2x2 guns), 0.06lbs / 0.03kg shells, 1915 Model
     Machine guns in deck mounts
     on side, all aft
   Weight of broadside 649 lbs / 294 kg
   Shells per gun, main battery: 150

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   3.00" / 76 mm   2.00" / 51 mm      2.00" / 51 mm
   2nd:   3.00" / 76 mm   2.00" / 51 mm      2.00" / 51 mm
   3rd:   0.50" / 13 mm         -               -
   4th:   0.50" / 13 mm         -               -

Machinery:
   Coal fired boilers, steam turbines,
   Direct drive, 2 shafts, 9,082 shp / 6,775 Kw = 20.00 kts
   Range 5,000nm at 12.00 kts
   Bunker at max displacement = 898 tons (100% coal)

Complement:
   229 - 298

Cost:
   £0.329 million / $1.315 million

Distribution of weights at normal displacement:
   Armament: 81 tons, 2.3 %
   Armour: 61 tons, 1.7 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 61 tons, 1.7 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 398 tons, 11.2 %
   Hull, fittings & equipment: 1,927 tons, 54.3 %
   Fuel, ammunition & stores: 630 tons, 17.8 %
   Miscellaneous weights: 449 tons, 12.7 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     9,282 lbs / 4,210 Kg = 85.9 x 6.0 " / 152 mm shells or 2.1 torpedoes
   Stability (Unstable if below 1.00): 1.26
   Metacentric height 3.7 ft / 1.1 m
   Roll period: 13.5 seconds
   Steadiness   - As gun platform (Average = 50 %): 71 %
         - Recoil effect (Restricted arc if above 1.00): 0.14
   Seaboat quality  (Average = 1.00): 1.09

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.550
   Length to Beam Ratio: 7.34 : 1
   'Natural speed' for length: 21.33 kts
   Power going to wave formation at top speed: 38 %
   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:      14.00 ft / 4.27 m
      - Forecastle (20 %):   14.00 ft / 4.27 m
      - Mid (50 %):      14.00 ft / 4.27 m
      - Quarterdeck (15 %):   14.00 ft / 4.27 m
      - Stern:      14.00 ft / 4.27 m
      - Average freeboard:   14.00 ft / 4.27 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 68.8 %
      - Above water (accommodation/working, high = better): 229.3 %
   Waterplane Area: 19,687 Square feet or 1,829 Square metres
   Displacement factor (Displacement / loading): 181 %
   Structure weight / hull surface area: 80 lbs/sq ft or 389 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.99
      - Longitudinal: 1.03
      - 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

[maddox]

I would like to see how the main guns are arranged.

6 6" forward on a cruiser. I see problems in firing arcs.
Unless the on the side guns are casemated or the  twin setup is superfiring. And even then.

Also, is it an amfibious assault support ship? Or a long range troop transport?

[Logi]

APA  - amphibous assualt ship

the main guns have limited firing arcs, its meant only to fire front really.

I'll get a gun arrangement picture up soon.

[P3D]

You need more that 250kg for each men plus boats plus accomodation for men plus hull strength to hold it. Try 1t - and that's for short-range transportation.

[maddox]

In le Magnificent it's 2 tons /soldier.  And that's without dedicated landing boats nor assorted stuff.

[Logi]

The ship does use the 1t for short-range transportation. Is there some additional weight for each men?

Also, where do you see 250kg? How did you arrive at that number?

[maddox]

Miscellaneous weights: 449 tons, 12.7 %


449tons /1796 troops= 250kg/troop

Chinese are of small posture. Dedicate 100 kg to the trooper himself - this means supplies and such for himself. 75 kg added weight to the ship (you need to have  things like extra toilets, washing spots , mess and  beds to lay those men). And then 75 kg for the boats and davits. No lightweight fiberglass in this age. Most small boats are wood. And wooden seagoing boats are heavy.

Sounds like a 17th century slaveship to me actualy

[Tanthalas]

Sounds like a 17th century slaveship to me actualy

or an Italian oceangoing Destroyer (I actualy wrote a story about the abismil conditions onboard them)

[Logi]

That comes up with 4475 troops each ship.

2983 troops for 150kg per trooper
2237 troops for 200kg per trooper
1790 troops for 250kg per trooper

Besides, slaveships are very efficent in carrying people :) I only worry about the troopers getting to the bathrooms in time. Besides, it's a APA, not a ocean liner. (One can only wonder where the complaint letters end up.)

[Tanthalas]

Miscellaneous weights: 449 tons

they are saying you need 1 ton per trooper, where you are giving each trooper 250kg (im no metric master but im fairly sure that isnt a ton)

so your ship could haul 449 troopers
where you say it can haul 1790 troopers.
see the problem?

Now I cant coment on this era, but I can tell you what conditions are like on USS Wasp(a LHD).  I had my own Rack (bed) Space to store all my Gear (including our own weapons locker just for the Marines) and she could haul up to 2200 Marines.

[maddox]

That comes up with 4475 troops each ship.

What comes with 4475 troops each ship?

2983 troops for 150kg per trooper
2237 troops for 200kg per trooper
1790 troops for 250kg per trooper

Each trooper needs  space. That space is at minimum -including his personal gear-2m³
to see what this space weights in a modern, steel ship I use the simple idea of a closet from sheet steel. 1mm think. 2m³ is 10m² steel sheet= 78,5 kg.
This means that the trooper doesn't have acces to things like a bathroom , personal hygiëne , food nor drink.

Besides, slaveships are very efficent in carrying people :)

There was a reason they stacked the slaves.  If 10% survived they got still a nice profit.

I only worry about the troopers getting to the bathrooms in time. Besides, it's a APA, not a ocean liner. (One can only wonder where the complaint letters end up.)

I rather think your troops will piss, shit and vomit in the sea. And the complaint letters are dandy toilet paper

[Logi]

Was it 75kg for each troopers' bathroom? I just subtracted 75kg from the overall misc weight once, same with the boats.

If so, that the ship really does carry 1790 troops (100kg).

For more space perhaps:

1496 troops, each trooper has an addition 50kg of room.

[maddox]

Nope, it's 78,5 kg each troop to provide a roof over his head, so he won't wash overboard if the sea does what the sea does.

On a ship 1mm sheet steel isn't used, even a simple locker on deck is 5mm corrugated steel.
So with the efficiency to build a quonset on the ship to stuff those guys, it's probably not far off.

But then you have the seagoing equivalent of a schoolbus. With only the facilities for the normal compliment of the crew. All 300 of them. 

Ever been at a festival were 2000 people used the same 10 toilets? (and here we neglect the fact of seasickness)

[Logi]

@ Tan
Sorry, I missed your post by mistake.

So:
500 troops (standard)
1200 troops (short-distance)

[Tanthalas]

@ Tan
Sorry, I missed your post by mistake.

So:
500 troops (standard)
1200 troops (short-distance)

Ya I could buy that