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Saturday, October 30th 2004, 6:48pm

1926 Seaplane Tenders/Carriers

I´m thinking on building 4 of these, they can work as tipical seaplane carriers and as depot/repair ships for the seaplanes of other units. They´re big enough to handle about 15-20 aircraft repairing at the same time.

I think they fit into the vessels not subject to limits in numbers or tonnage, If I´ve done anything wrong just tell me. What do you think about them?

ST26, British Seaplane Carrier / Tender laid down 1926

10 Supermarine Seagull III as permanent air group.



They can also have their airgroup replaced by smaller-faster seaplanes that can act as defensive fighters.

2 catapults, one at each side.

Displacement:
8.267 t light; 8.500 t standard; 10.465 t normal; 11.995 t full load

Dimensions: Length overall / water x beam x draught
554,58 ft / 550,00 ft x 60,00 ft x 19,82 ft (normal load)
169,04 m / 167,64 m x 18,29 m x 6,04 m

Armament:
4 - 4,50" / 114 mm guns (2x2 guns), 45,56lbs / 20,67kg shells, 1926 Model
Breech loading guns in deck mounts
on centreline, all forward, 1 raised mount - superfiring
8 - 1,57" / 40,0 mm guns (2x4 guns), 1,95lbs / 0,88kg shells, 1926 Model
Dual purpose guns in deck mounts
on side, all amidships
8 - 0,79" / 20,0 mm guns (4x2 guns), 0,24lbs / 0,11kg shells, 1926 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
Weight of broadside 200 lbs / 91 kg
Shells per gun, main battery: 200

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 15.118 shp / 11.278 Kw = 20,00 kts
Range 9.350nm at 18,00 kts (Bunkerage = 3.537 tons)

Complement:
516 - 672

Cost:
£1,306 million / $5,224 million

Distribution of weights at normal displacement:
Armament: 25 tons, 0,2 %
Machinery: 484 tons, 4,6 %
Hull, fittings & equipment: 4.758 tons, 45,5 %
Fuel, ammunition & stores: 2.198 tons, 21,0 %
Miscellaneous weights: 3.000 tons, 28,7 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
22.462 lbs / 10.189 Kg = 493,0 x 4,5 " / 114 mm shells or 3,6 torpedoes
Stability (Unstable if below 1.00): 1,00
Metacentric height 2,3 ft / 0,7 m
Steadiness - As gun platform (Average = 50 %): 85 %
- Recoil effect (Restricted arc if above 1.00): 0,03
Seaboat quality (Average = 1.00): 1,69

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0,560
Length to Beam Ratio: 9,17 : 1
'Natural speed' for length: 23,45 kts
Power going to wave formation at top speed: 36 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 10,00 degrees
Stern overhang: 0,00 ft / 0,00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 26,00 ft / 7,92 m
- Forecastle (20 %): 18,00 ft / 5,49 m
- Mid (50 %): 18,00 ft / 5,49 m
- Quarterdeck (15 %): 18,00 ft / 5,49 m
- Stern: 18,00 ft / 5,49 m
- Average freeboard: 18,64 ft / 5,68 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 49,2 %
- Above water (accommodation/working, high = better): 150,1 %
Waterplane Area: 22.586 Square feet or 2.098 Square metres
Displacement factor (Displacement / loading): 251 %
Structure weight / hull surface area: 133 lbs/sq ft or 650 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1,64
- Longitudinal: 1,89
- Overall: 1,66
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

Sardines

Unregistered

2

Saturday, October 30th 2004, 7:41pm

Treaty Bending

Gravina you are so close to a major loop hole in the treaty


(b) Naval surface combatant vessels exceeding 600 tons (610 metric

tons), but not exceeding 2,000 tons (2,032 metric tons) standard

displacement, provided they have none of the following

characteristics:

(1) Mount a gun above 5.1 inch (130 mm) calibre;

(2) Mount more than eight guns above 3 inch (76 mm) calibre;

(3) Are designed or fitted to launch torpedoes;

(4) Are designed for a speed greater than 24 knots.

(5) Are fitted to receive aircraft on board from the air.

*********
Please note (5) aircraft limitations
essentially no arrestor gear however this is so worded that you can design the ship for arrestor gear without breaking the treaty as it isn't FITTED.

for comparison find the USNs Barnegat class seaplane tenders and convert to flush deck.

compare with below

(c) Naval surface vessels not specifically built as fighting ships

which are employed on fleet duties or as troop transports or in

some other way than as fighting ships, provided they have none of

the following characteristics:

(1) Mount a gun above 6 inch (153 mm) calibre;

(2) Mount more than four guns above 3 inch (76 mm) calibre;

(3) Are designed or fitted to launch torpedoes:

(4) Are designed for a speed greater than 20 knots;

(5) Are protected by armour plate on the hull;

(6) Are designed or fitted to launch mines;

(7) Are fitted to receive aircraft on board from the air;

(8) Mount more than one aircraft-launching apparatus on the

centre line; or two, one on each broadside;

(9) If fitted with any means of launching aircraft into the air,

are designed or adapted to operate at sea more than ten

aircraft.

***************

essentially no more than 1/2 catapults and 10 aircraft (your ship will break this as it should easily carry far more aircraft than you list.


ONE TREATY BENDER

HMAS Tern, Australia Seaplane Tender/Escort Carrier laid down 1923

Displacement:
1,897 t light; 2,000 t standard; 2,568 t normal; 3,023 t full load

Dimensions: Length overall / water x beam x draught
403.04 ft / 390.00 ft x 50.00 ft x 10.50 ft (normal load)
122.85 m / 118.87 m x 15.24 m x 3.20 m

Armament:
8 - 4.72" / 120 mm guns (4x2 guns), 50.00lbs / 22.68kg shells, 1923 Model
Dual purpose guns in deck mounts
on side ends, evenly spread
16 - 1.57" / 40.0 mm guns (4x4 guns), 1.95lbs / 0.88kg shells, 1923 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
16 - 0.79" / 20.0 mm guns (8x2 guns), 0.24lbs / 0.11kg shells, 1923 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
Weight of broadside 435 lbs / 197 kg
Shells per gun, main battery: 200

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

- Conning tower: 0.50" / 13 mm

Machinery:
Diesel Internal combustion generators,
Electric motors, 2 shafts, 7,253 shp / 5,410 Kw = 21.00 kts
Range 10,000nm at 15.00 kts (Bunkerage = 1,023 tons)

Complement:
179 - 234

Cost:
£0.431 million / $1.724 million

Distribution of weights at normal displacement:
Armament: 57 tons, 2.2 %
Armour: 13 tons, 0.5 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 11 tons, 0.4 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 2 tons, 0.1 %
Machinery: 242 tons, 9.4 %
Hull, fittings & equipment: 985 tons, 38.3 %
Fuel, ammunition & stores: 671 tons, 26.1 %
Miscellaneous weights: 600 tons, 23.4 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
4,783 lbs / 2,170 Kg = 91.0 x 4.7 " / 120 mm shells or 1.5 torpedoes
Stability (Unstable if below 1.00): 1.32
Metacentric height 2.9 ft / 0.9 m
Roll period: 12.4 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.07
Seaboat quality (Average = 1.00): 1.35

Hull form characteristics:
Hull has a flush deck
and transom stern
Block coefficient: 0.439
Length to Beam Ratio: 7.80 : 1
'Natural speed' for length: 23.21 kts
Power going to wave formation at top speed: 44 %
Trim (Max stability = 0, Max steadiness = 100): 52
Bow angle (Positive = bow angles forward): 15.00 degrees
Stern overhang: 5.00 ft / 1.52 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 30.00 ft / 9.14 m
- Forecastle (20 %): 10.00 ft / 3.05 m
- Mid (50 %): 10.00 ft / 3.05 m
- Quarterdeck (15 %): 10.00 ft / 3.05 m
- Stern: 10.00 ft / 3.05 m
- Average freeboard: 11.60 ft / 3.54 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 74.3 %
- Above water (accommodation/working, high = better): 136.3 %
Waterplane Area: 12,805 Square feet or 1,190 Square metres
Displacement factor (Displacement / loading): 165 %
Structure weight / hull surface area: 59 lbs/sq ft or 288 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.99
- Longitudinal: 1.05
- 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

Russell

3

Saturday, October 30th 2004, 9:04pm

I´m not trying to bend the treaty, althought I can see your point. I´m just proposing a large seaplane carrier, that can (and will mostly) act as a tender and support ship.

Instead of small 2000t ships I was aiming towards bigger vessels, with longer patrol times, such as the Commandant Teste (10000t,), the US Tangier (8000t), Curtiss (8625t) and Currituck (9090t) classes, or the japanese Notoro and Kamoi (these are even bigger). They´re supposed to operate in the Pacific or Indian Ocean most of the time.

HoOmAn

Keeper of the Sacred Block Coefficient

  • Send private message

4

Sunday, October 31st 2004, 12:33am

Quoted

Originally posted by Sardines
(5) Are fitted to receive aircraft on board from the air.

*********
Please note (5) aircraft limitations
essentially no arrestor gear however this is so worded that you can design the ship for arrestor gear without breaking the treaty as it isn't FITTED.


First of all, welcome to the boards!

Second - this is not a loophole as the characteristics apply permanetly and not _as build_.

When Pengolodh and I discussed early versions of the CT Peng came up with the above to prevent people from making use of non-limited tonnage to get carriers and the like.

One idea we had for example was to build a 2000ts, 24kn "gunboat" on which a non-permanent landing platform could be rigged on non-permanent supporting structure. The ship would then be able to launch A/Cs by catapults and receive them from air later on.

Doesn´t work. In the very moment the landing platform is fitted the ship has to be rated against a powers carrier tonnage. If all CV tonnage is already used said ship would thus violate the treaty. If tonnage is still available nobody cares as 2000ts carriers are allowed anyway - useful or not.

So I don´t think there is any loophole...

5

Sunday, October 31st 2004, 2:11am

Not to mention that if these treaty stipulations were violated it would likely be in the event of a war or the treaty colapsing due to lack of participation when a major signatory exits the treaty.

6

Sunday, October 31st 2004, 11:26am

The Greek navy is considering the same idea although on a bigger scale. There are three concepts to test;
1. the aircraft carrier to operate with the fleet. 15,000tons
2. a seaplane carrier/mobile base. 13,000tons
3. a mobile base. 2,000tons

The seaplane carrier is in the same theme as Commandant Teste, Kamoi, Notoro and is of the same era. The idea is to setup base for patrol aircraft and be able to fuel and maintain them for an extended period. While they are limited to to 10 aircraft, (the treaty dowesn't say 10 'Fairy Flycatchers' or 10 'Spruce Gooses'). A large ship can operate more than 10 aircraft but these can be flown in to the 'mobile base'

The small ship (2000tons) can also operate as a moblie base but not as many aircraft or for as long and could not really operate her aircraft at sea as the larger ship could - but not as capable as a real aircraft carrier.

So Greece is probably going to build a 13,000ton seaplane carrier in 1925 which is legal under the treaty.

I'm also working on a multipurpose frigate that will fill the small mobile base category.

Cheers,

---
AV1925, GREEK aircraft tender laid down 1925

Displacement:
12,800 t light; 13,150 t standard; 15,324 t normal; 17,002 t full load
Loading submergence 816 tons/feet

Dimensions:
664.00 ft x 76.80 ft x 25.00 ft (normal load)
202.39 m x 23.41 m x 7.62 m

Armament:
4 - 6.00" / 152 mm guns (2 Main turrets x 2 guns)
24 - 2.00" / 51 mm guns
8 - 0.50" / 13 mm AA guns
Weight of broadside 529 lbs / 240 kg

Armour:
Main turrets 1.00" / 25 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 18,117 shp / 13,515 Kw = 20.00 kts
Range 12,500nm at 15.00 kts

Complement:
688 - 895

Cost:
£1.917 million / $7.669 million

Distribution of weights at normal displacement:
Armament: 66 tons, 0.4 %
Armour: 39 tons, 0.3 %
Belts: 0 tons, 0.0 %, Armament: 39 tons, 0.3 %, Armour Deck: 0 tons, 0.0 %
Conning Tower: 0 tons, 0.0 %, Torpedo bulkhead: 0 tons, 0.0 %
Machinery: 588 tons, 3.8 %
Hull, fittings & equipment: 4,757 tons, 31.0 %
Fuel, ammunition & stores: 2,524 tons, 16.5 %
Miscellaneous weights: 7,350 tons, 48.0 %

Metacentric height 3.7

Remarks:
Hull space for machinery, storage & compartmentation is excellent
Room for accommodation & workspaces is excellent
Excellent seaboat, comfortable and able to fight her guns in the heaviest weather

Estimated overall survivability and seakeeping ability:
Relative margin of stability: 1.05
Shellfire needed to sink: 23,591 lbs / 10,701 Kg = 218.4 x 6.0 " / 152 mm shells
(Approx weight of penetrating shell hits needed to sink ship excluding critical hits)
Torpedoes needed to sink: 3.1
(Approx number of typical torpedo hits needed to sink ship)
Relative steadiness as gun platform: 46 %
(Average = 50 %)
Relative rocking effect from firing to beam: 0.06
Relative quality as seaboat: 1.51

Hull form characteristics:
Block coefficient: 0.421
Sharpness coefficient: 0.32
Hull speed coefficient 'M': 8.18
'Natural speed' for length: 25.77 kts
Power going to wave formation at top speed: 28 %
Trim: 28
(Maximise stabilty/flotation = 0, Maximise steadiness/seakeeping = 100)

Estimated hull characteristics & strength:
Underwater volume absorbed by magazines and engineering spaces: 68.6 %
Relative accommodation and working space: 158.1 %
(Average = 100%)
Displacement factor: 169 %
(Displacement relative to loading factors)
Relative cross-sectional hull strength: 0.98
(Structure weight / hull surface area: 102 lbs / square foot or 497 Kg / square metre)
Relative longitudinal hull strength: 1.20
(for 20.00 ft / 6.10 m average freeboard, freeboard adjustment 3.51 ft)
Relative composite hull strength: 1.00

7

Sunday, October 31st 2004, 12:50pm

Exactly

Quoted

The idea is to setup base for patrol aircraft and be able to fuel and maintain them for an extended period. While they are limited to to 10 aircraft, (the treaty dowesn't say 10 'Fairy Flycatchers' or 10 'Spruce Gooses'). A large ship can operate more than 10 aircraft but these can be flown in to the 'mobile base'


The Russian seaplane tenders laid down last year and this use the same concept - they each carry 8 single-engine seaplanes, but will support another half-squadron of 8 twin-engine seaplanes which self-deploy.

We'll see how long it takes these 16 aircraft to get through 1,250 tons of supplies. I'd better assign a small tanker with aviation fuel to accompany it :-)

The ~7,000 tons of supplies ought to support operations for a good while.

8

Sunday, October 31st 2004, 2:28pm

The Philippines intends to build a "one for all" tender in 1929; 4,000 tons, 8 a/c and the ability to also support a torpedo-boat and/or submarine squadron.