WesWorld

Two of these are planned as flagships for escort squadrons and for amphibious groups. They will have significant aircraft facilities aft, as well as flag facilities and communication equipment.


HMAS Erebrus/Terror, Australia Escort Cruiser laid down 1943

Displacement:
7,002 t light; 7,408 t standard; 8,375 t normal; 9,148 t full load

Dimensions: Length overall / water x beam x draught
545.98 ft / 540.00 ft x 59.00 ft x 18.40 ft (normal load)
166.42 m / 164.59 m x 17.98 m x 5.61 m

Armament:
6 - 9.20" / 234 mm guns (2x3 guns), 389.34lbs / 176.60kg shells, 1943 Model
Breech loading guns in turrets (on barbettes)
on centreline, all forward, 1 raised mount - superfiring
10 - 4.70" / 119 mm guns (5x2 guns), 51.91lbs / 23.55kg shells, 1943 Model
Dual purpose guns in deck mounts with hoists
on side, evenly spread, 1 raised mount
16 - 1.57" / 40.0 mm guns (4x4 guns), 1.95lbs / 0.89kg shells, 1943 Model
Anti-aircraft guns in deck mounts
on centreline, evenly spread
12 - 0.79" / 20.0 mm guns (6x2 guns), 0.24lbs / 0.11kg shells, 1943 Model
Breech loading guns in deck mounts
on side, evenly spread
Weight of broadside 2,889 lbs / 1,311 kg
Shells per gun, main battery: 142
6 - 21.0" / 533.4 mm above water torpedoes

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 5.00" / 127 mm 240.00 ft / 73.15 m 9.00 ft / 2.74 m
Ends: Unarmoured
Main Belt covers 68 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 5.00" / 127 mm 2.00" / 51 mm 5.00" / 127 mm
2nd: 1.20" / 30 mm - -

- Armour deck: 2.00" / 51 mm, Conning tower: 5.00" / 127 mm

Machinery:
Diesel Internal combustion generators plus batteries,
Electric motors, 4 shafts, 23,574 shp / 17,586 Kw = 24.20 kts
Range 10,000nm at 15.00 kts
Bunker at max displacement = 1,740 tons

Complement:
437 - 569

Cost:
£4.148 million / $16.591 million

Distribution of weights at normal displacement:
Armament: 361 tons, 4.3 %
Armour: 1,697 tons, 20.3 %
- Belts: 486 tons, 5.8 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 350 tons, 4.2 %
- Armour Deck: 817 tons, 9.8 %
- Conning Tower: 44 tons, 0.5 %
Machinery: 609 tons, 7.3 %
Hull, fittings & equipment: 3,795 tons, 45.3 %
Fuel, ammunition & stores: 1,373 tons, 16.4 %
Miscellaneous weights: 540 tons, 6.4 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
15,344 lbs / 6,960 Kg = 39.4 x 9.2 " / 234 mm shells or 2.5 torpedoes
Stability (Unstable if below 1.00): 1.08
Metacentric height 2.6 ft / 0.8 m
Roll period: 15.2 seconds
Steadiness - As gun platform (Average = 50 %): 72 %
- Recoil effect (Restricted arc if above 1.00): 0.91
Seaboat quality (Average = 1.00): 1.60

Hull form characteristics:
Hull has a flush deck
and transom stern
Block coefficient: 0.500
Length to Beam Ratio: 9.15 : 1
'Natural speed' for length: 26.70 kts
Power going to wave formation at top speed: 44 %
Trim (Max stability = 0, Max steadiness = 100): 45
Bow angle (Positive = bow angles forward): 9.00 degrees
Stern overhang: 2.50 ft / 0.76 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 22.00 ft / 6.71 m
- Forecastle (30 %): 17.00 ft / 5.18 m
- Mid (50 %): 17.00 ft / 5.18 m
- Quarterdeck (20 %): 17.00 ft / 5.18 m
- Stern: 17.00 ft / 5.18 m
- Average freeboard: 17.60 ft / 5.36 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 64.6 %
- Above water (accommodation/working, high = better): 142.3 %
Waterplane Area: 22,075 Square feet or 2,051 Square metres
Displacement factor (Displacement / loading): 132 %
Structure weight / hull surface area: 115 lbs/sq ft or 562 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.95
- Longitudinal: 1.56
- 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
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

An interesting design, but one thing strikes me odd at the start.

Quoted

10 - 4.70" / 119 mm guns (5x2 guns), 51.91lbs / 23.55kg shells, 1943 Model
Dual purpose guns in deck mounts with hoists
on side, evenly spread, 1 raised mount

Odd number of mounts to port or to starboard?

I'm guessing there's supposed to be one raised mount superfiring over "A" turret, with the other four on the sides.

Quoted

Originally posted by The Rock Doctor
I'm guessing there's supposed to be one raised mount superfiring over "A" turret, with the other four on the sides.

That's what I'd guess too, but I find the whole concept of the "Escort Cruiser" alien and prefer to make no assumptions.

Reminder, the Commonwealth 9.2" gun is rated for 510lbs shells.

Then sim it as such.

Quoted

Originally posted by The Rock Doctor
Then sim it as such.

What he said.

*grumble* Computer died and took my yet unsaved SS2 file of Erebrus with it so have to redo it from scratch.

Here is a dedicated amphibious transport based a bit on the Canadian Vimy Ridge.


Drawing is still work in progress. Borrowed a few stuff from Rocky.

HMAS Coral Sea, Australia Amphibious Transport laid down 1943

Displacement:
7,501 t light; 7,694 t standard; 8,739 t normal; 9,574 t full load

Dimensions: Length overall / water x beam x draught
540.00 ft / 540.00 ft x 64.00 ft x 15.00 ft (normal load)
164.59 m / 164.59 m x 19.51 m x 4.57 m

Armament:
1 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1943 Model
Breech loading gun in a deck mount with hoist
on centreline amidships
16 - 1.57" / 40.0 mm guns (4x4 guns), 1.95lbs / 0.89kg shells, 1943 Model
Breech loading guns in deck mounts
on side, evenly spread
12 - 0.79" / 20.0 mm guns (6x2 guns), 0.24lbs / 0.11kg shells, 1943 Model
Breech loading guns in deck mounts
on side, evenly spread
Weight of broadside 142 lbs / 64 kg
Shells per gun, main battery: 200

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 1.00" / 25 mm 150.00 ft / 45.72 m 10.00 ft / 3.05 m
Ends: Unarmoured
Main Belt covers 43 % of normal length
Main belt does not fully cover magazines and engineering spaces

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.00" / 25 mm - -

- Armour deck: 0.50" / 13 mm

Machinery:
Diesel Internal combustion generators plus batteries,
Electric motors, 2 shafts, 12,875 shp / 9,605 Kw = 20.00 kts
Range 10,200nm at 15.00 kts
Bunker at max displacement = 1,880 tons

Complement:
451 - 587

Cost:
£2.121 million / $8.483 million

Distribution of weights at normal displacement:
Armament: 18 tons, 0.2 %
Armour: 323 tons, 3.7 %
- Belts: 78 tons, 0.9 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 4 tons, 0.0 %
- Armour Deck: 241 tons, 2.8 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 333 tons, 3.8 %
Hull, fittings & equipment: 2,828 tons, 32.4 %
Fuel, ammunition & stores: 1,238 tons, 14.2 %
Miscellaneous weights: 4,000 tons, 45.8 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
15,927 lbs / 7,225 Kg = 147.5 x 6.0 " / 152 mm shells or 2.6 torpedoes
Stability (Unstable if below 1.00): 1.07
Metacentric height 2.9 ft / 0.9 m
Roll period: 15.8 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.02
Seaboat quality (Average = 1.00): 1.52

Hull form characteristics:
Hull has raised forecastle, raised quarterdeck
and transom stern
Block coefficient: 0.590
Length to Beam Ratio: 8.44 : 1
'Natural speed' for length: 26.61 kts
Power going to wave formation at top speed: 37 %
Trim (Max stability = 0, Max steadiness = 100): 46
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: 24.00 ft / 7.32 m
- Forecastle (20 %): 20.00 ft / 6.10 m (15.00 ft / 4.57 m aft of break)
- Mid (50 %): 15.00 ft / 4.57 m
- Quarterdeck (20 %): 20.00 ft / 6.10 m (15.00 ft / 4.57 m before break)
- Stern: 20.00 ft / 6.10 m
- Average freeboard: 17.32 ft / 5.28 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 64.6 %
- Above water (accommodation/working, high = better): 165.3 %
Waterplane Area: 26,093 Square feet or 2,424 Square metres
Displacement factor (Displacement / loading): 170 %
Structure weight / hull surface area: 80 lbs/sq ft or 392 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.06
- Longitudinal: 0.98
- 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
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

2000 tons - 1000 Troops and equipment.
1000 tons - 120x40x10 Well Deck
300 tons - 1 LCT (Landing Craft, Tank)
320 tons - 8 LCI (Landing Craft, Infantry)
200 tons - Tanks and vehicles
150 tons - Aircraft facilities
30 tons - Radar, Radio, C3

The freeboard in the drawing looks rather too low for a troop carrier, at least in my eyes. Most of the historical ships of this class had much higher freeboards.

It's probably a bit too early to try to put helicopters on an amphibious assault ship.

Perhaps it'd be better to start from the basis of the British Glen class landing ship dock. You'd get a bigger well deck, which is the entire purpose of the ship. What's Australia's amphibious doctrine, and what's driving their acquisition of the ship? What sort of roles is it being created for?

Quoted

Originally posted by Brockpaine
Perhaps it'd be better to start from the basis of the British Glen class landing ship dock. You'd get a bigger well deck, which is the entire purpose of the ship.

That seems to be an implied criticism of the Vimy Ridge class, sir.

Quoted

Originally posted by ShinRa_Inc
That seems to be an implied criticism of the Vimy Ridge class, sir.

I'd need to see the sim of the Vimy Ridge class design to criticize it. As it is, I'm just pointing out the flaw in this ship that I see - the well deck is too small to be really useful. The well decks of the Glens and France's Chateaurenault are already quite cramped compared to historical LSDs, and yet this dock is only 65% as large.

Incidentally, we've set the weight of water in a well deck at one ton per cubic meter. The current volume of the well deck is 1359.2 cubic meters, so 1,000 tons shan't cover it according to our rules.

I'd agree on the size of the well deck, needs to be bigger.

I'd ditch the armour, its not really adding much to protection. If you really want armour then I'd go for a 1in deck over the magazines and vital command bits and drop the belt.
Aslo I'd drop the 6in from the centre of the ship, can't see it having any useful arcs there being cramped between two cranes etc.

Well I am definitely not an expert on amphibious ships so don't know what is an adequate freeboard. I just based alot of specs on the Vimy Ridge class including the well deck, figuring Australia would have cooperated and gotten advise from Canada, with the deck being sized the same for commonality. As far as the water, the well deck wouldn't be completely filled.

No helos, facilities are for floatplanes and autogyros.

Armor belt is for specific critical areas. Armored deck represents strengthened decks to support tanks, landing craft, etc.

6in gun is the same as the Canadian 7.5in, a spare gun to give some fire support. I had the gun forward, but the middle seemed empty.

Quoted

What's Australia's amphibious doctrine, and what's driving their acquisition of the ship? What sort of roles is it being created for?

Umm, be able to land a 1,000 man force anywhere? Not my forte.

the RCN is more than willing to undertake a joint design with the RAN (Vimy Ridge will probably be getting a revision when I have the time). There's plenty of 7.5" guns to go around, as well.

Quoted

Originally posted by Desertfox
Well I am definitely not an expert on amphibious ships so don't know what is an adequate freeboard. I just based alot of specs on the Vimy Ridge class including the well deck, figuring Australia would have cooperated and gotten advise from Canada, with the deck being sized the same for commonality. As far as the water, the well deck wouldn't be completely filled.

No helos, facilities are for floatplanes and autogyros.

Armor belt is for specific critical areas. Armored deck represents strengthened decks to support tanks, landing craft, etc.

6in gun is the same as the Canadian 7.5in, a spare gun to give some fire support. I had the gun forward, but the middle seemed empty.

Quoted

What's Australia's amphibious doctrine, and what's driving their acquisition of the ship? What sort of roles is it being created for?

Umm, be able to land a 1,000 man force anywhere? Not my forte.

Having critiqued the Vimy Ridge design, I suppose I am qualified to comment on the proposed RAN Coral Sea.

As Brock has commented the docking well is small, and the amount of miscellaneous weight allocated in the sim is not correct. It is worth noting that the proper volume of the water in the well deck is calculated by the length x width x depth of water in the well dock at full flood; perhaps the dimensions given (which I presume are in feet, not meters) include too deep a depth of water. This is an area in which savings could be considered.

I would also agree with Hood that the center location for the main gun renders it pretty useless – restricted firing arcs and blast effects could make it more dangerous to the ship’s own crew rather than the enemy.

For landing a thousand troops ashore she is quite an investment, and a poor return on it. A number of smaller LST type landing ships could accomplish the same tasks and be built in a far shorter time. In fact, LST type vessels would be of greater utility, being able to haul cargo to Australia’s bases in the Northern Territories, in Papua or in the nearby islands. Troops – if required – could be carried far less expensively in mercantile conversions.

Permit me to offer a possible alternative. Bruce said an LST design might be a cheaper way of accomplishing the task, which I think might be a good choice. It avoids putting all Australia's amphibious eggs in one basket, and for the tonnage could offer more versatility than the Coral Sea design proposed above.

This is just a proposal, of course, but I wanted to offer a design for comparative purposes in order to demonstrate the potential advantages.

Quoted

Keppel Bay, Australian LST laid down 1943

Displacement:
2,477 t light; 2,555 t standard; 3,038 t normal; 3,425 t full load

Dimensions: Length overall / water x beam x draught
320.79 ft / 310.00 ft x 49.00 ft x 10.00 ft (normal load)
97.78 m / 94.49 m x 14.94 m x 3.05 m

Armament:
8 - 1.57" / 40.0 mm guns (2x4 guns), 1.95lbs / 0.89kg shells, 1943 Model
Anti-aircraft guns in deck mounts
on centreline ends, evenly spread
8 - 0.79" / 20.0 mm guns (4x2 guns), 0.24lbs / 0.11kg shells, 1943 Model
Machine guns in deck mounts
on side, all amidships, all raised mounts - superfiring
Weight of broadside 18 lbs / 8 kg
Shells per gun, main battery: 1,500

Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 3,964 shp / 2,957 Kw = 16.00 kts
Range 7,500nm at 15.00 kts
Bunker at max displacement = 870 tons

Complement:
203 - 265

Cost:
£0.673 million / $2.694 million

Distribution of weights at normal displacement:
Armament: 2 tons, 0.1 %
Machinery: 102 tons, 3.4 %
Hull, fittings & equipment: 873 tons, 28.7 %
Fuel, ammunition & stores: 561 tons, 18.5 %
Miscellaneous weights: 1,500 tons, 49.4 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
5,791 lbs / 2,627 Kg = 2,965.5 x 1.6 " / 40 mm shells or 1.6 torpedoes
Stability (Unstable if below 1.00): 1.14
Metacentric height 2.2 ft / 0.7 m
Roll period: 13.9 seconds
Steadiness - As gun platform (Average = 50 %): 76 %
- Recoil effect (Restricted arc if above 1.00): 0.00
Seaboat quality (Average = 1.00): 1.76

Hull form characteristics:
Hull has raised forecastle
Block coefficient: 0.700
Length to Beam Ratio: 6.33 : 1
'Natural speed' for length: 17.61 kts
Power going to wave formation at top speed: 44 %
Trim (Max stability = 0, Max steadiness = 100): 43
Bow angle (Positive = bow angles forward): 25.00 degrees
Stern overhang: 1.00 ft / 0.30 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 21.00 ft / 6.40 m
- Forecastle (20 %): 19.00 ft / 5.79 m (12.00 ft / 3.66 m aft of break)
- Mid (50 %): 12.00 ft / 3.66 m
- Quarterdeck (15 %): 12.00 ft / 3.66 m
- Stern: 12.00 ft / 3.66 m
- Average freeboard: 13.56 ft / 4.13 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 66.5 %
- Above water (accommodation/working, high = better): 137.1 %
Waterplane Area: 12,175 Square feet or 1,131 Square metres
Displacement factor (Displacement / loading): 176 %
Structure weight / hull surface area: 54 lbs/sq ft or 262 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.96
- Longitudinal: 1.41
- 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
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

Notes:
- Under LST rules, 1727t to construct.
- Sloping bottom of vessel has average draft of 10': 7-8' forward, 12-13' aft.

Breakdown of Miscellaneous Weights:
- 144 tons for four British Landing Craft Vehicle (LCV1) @ 36 tons each.
- 16 tons for forward ramp, etc
- 1346 tons for tanks, cargo, trucks, or troops (up to 10 tanks plus 15 trucks); max of 650 troops

Ships in Class:
- Keppel Bay
- Shoalwater Bay
- Bramble Bay

I used the British LCV1 design for an embarked landing craft.

Three of these vessels, at 1727t a pop, would be built for 5181 tons (and would include four LCV1s in the cost), vice the 6,500t final cost of the single Coral Sea design. Although the Coral Sea would carry more troops, tanks, and light vehicles, the three smaller craft, such as the Keppel Bay design proposed, could carry almost twice as many troops between them (although it would drop somewhat with the addition of tanks, trucks, or cargo.)

Sorry - what is this LST Rule?

Since this seems to be spinning out of the RCN plans, I'll point out the RCN's intention is for a pair of large LPDs, and 8 smaller (2500t light) LSMs, which I appearenently never got around to posting a springsharp for. I found one in my files and have posted it, but I'm sure there's a reason I didn't post it back during the original discussion.

Quoted

Originally posted by The Rock Doctor
Sorry - what is this LST Rule?

Subtract half the miscellaneous weight from the light displacement when calculating cost.

Though looking back at the rules, I forgot that embarked landing craft need to be purchased separately.

Quoted

- LSTs are build to special rules because of them being a mix of a freighter and a warship
- The miscellaneous weight of LST is halved into deductable and non-deductable (50/50)
- The deductable weight is taken of the ships light displacement and so building time and building costs
- Otherwise all normal building rules apply
- For scrapping LST only the reduced weight is used for calculation.
- Any landing craft carried aboard the LST shall be purchased separately under light craft rules.

Does that apply to all landing vessels in general, or just LSTs specifically?