WesWorld

A design study recently placed before the Admiralstab for consideration.

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Wittelsbach – German Large Landing Ship laid down 1943

Displacement: 6,477 t light; 6,711 t standard; 10,164 t normal; 12,926 t full load

Dimensions: Length overall / water x beam x draught

504.96 ft / 492.13 ft x 72.18 ft x 18.04 ft (normal load) [153.91 m / 150.00 m x 22.00 m x 5.50 m]

Armament:

2 - 4.13" / 105 mm guns (1x2 guns), 35.32lbs / 16.02kg shells, 1943 Model Dual purpose guns in deck mount on centreline forward, all raised guns - superfiring
16 - 1.46" / 37.0 mm guns (8x2 guns), 1.55lbs / 0.70kg shells, 1938 Model Anti-aircraft guns in deck mounts on side, evenly spread
Weight of broadside 95 lbs / 43 kg
Shells per gun, main battery: 500

Machinery:

Diesel Internal combustion motors, Geared drive, 2 shafts, 6,401 shp / 4,775 Kw = 16.00 kts
Range 28,250nm at 16.00 kts
Bunker at max displacement = 6,215 tons

Complement: 505 - 657

Cost: £1.701 million / $6.803 million

Distribution of weights at normal displacement:

Armament: 12 tons, 0.1 %
Machinery: 165 tons, 1.6 %
Hull, fittings & equipment: 2,899 tons, 28.5 %
Fuel, ammunition & stores: 3,687 tons, 36.3 %
Miscellaneous weights: 3,400 tons, 33.5 %

Overall survivability and seakeeping ability:

Survivability (Non-critical penetrating hits needed to sink ship): 29,846 lbs / 13,538 Kg = 845.0 x 4.1 " / 105 mm shells or 4.7 torpedoes
Stability (Unstable if below 1.00): 1.26
Metacentric height 4.7 ft / 1.4 m
Roll period: 14.0 seconds
Steadiness - As gun platform (Average = 50 %): 71 %
- Recoil effect (Restricted arc if above 1.00): 0.01
Seaboat quality (Average = 1.00): 1.68

Hull form characteristics:

Hull has low quarterdeck and transom stern
Block coefficient: 0.555
Length to Beam Ratio: 6.82: 1
'Natural speed' for length: 25.97 kts
Power going to wave formation at top speed: 31 %
Trim (Max stability = 0, Max steadiness = 100): 42
Bow angle (Positive = bow angles forward): 20.00 degrees
Stern overhang: 3.28 ft / 1.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 26.25 ft / 8.00 m
- Forecastle (20 %): 21.33 ft / 6.50 m
- Mid (50 %): 16.40 ft / 5.00 m
- Quarterdeck (30 %): 9.84 ft / 3.00 m (16.40 ft / 5.00 m before break)
- Stern: 9.84 ft / 3.00 m
- Average freeboard: 16.55 ft / 5.05 m

Ship space, strength and comments:

Space - Hull below water (magazines/engines, low = better): 44.0 %
- Above water (accommodation/working, high = better): 174.9 %
Waterplane Area: 25,932 Square feet or 2,409 Square metres
Displacement factor (Displacement / loading): 266 %
Structure weight / hull surface area: 84 lbs/sq ft or 412 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.98
- Longitudinal: 1.20
- 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:

4,389 tons for water in well deck simmed as fuel; range is actually 8,000nm at 16 knots

After section of well deck is 101 meters long, 13.4 meters wide with 2.8 meters depth of water, Forward section of well deck is 16.8 meters long, 8.4 meters wide with 2.4 meters depth of water; total weight of water 4,229 tons

Breakdown of Miscellaneous Weights:

Provision for 220 troops - 440 tons
Provision for eight PLB40 landing craft in docking well - 496 tons
Provision for two SLB40 landing craft in davits - 50 tons
Provision for 14 tanks @ 40 tons - 560 tons
Provision for 50 vehicles @ 12 tons - 600 tons
Provision for small boat repair shop and two cranes - 250 tons
Provision for high capacity pumps (to drain or flood well deck) - 54 tons
Provision for vehicle, tank and landing craft spare parts - 100 tons
Provision for combat-loaded supplies - 750 tons
Provision for radar and communications equipment - 100 tons
Total - 3400 tons

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My thanks to Brock for his guidance and suggestions through the design process.

Quite interesting. The well deck is much larger than the others being constructed or built around the world...

Can't wait to see a drawing of her

Quoted

Originally posted by Brockpaine
Quite interesting. The well deck is much larger than the others being constructed or built around the world...

Yes, it is.

The dimensions of the docking well approximate those of the US Ashland class of WW2. "Allied Landing Craft of World War Two" - ONI226 - has a schematic drawing of the class which shows the well dimensions - and it runs practically from stem to stern.

The current generation of German landing craft are rather larger than their foreign counterparts, and as they represent the "main battery" of a dock landing ship, the vessel needs to be designed around their parameters.

Landing ships built elsewhere - such as the French Chaueaurenaults or British Glens - seem to be closer to the LPD assault ship in concept - carrying a far larger troop contingent. Current German practice is to have troops carried by landing ships converted from merchantmen (the Frundsberg class LSIs) and have the Wittelsbach's larger landing craft available to land follow-on forces and most importantly supplies.

Quoted

Originally posted by BruceDuncan
The current generation of German landing craft are rather larger than their foreign counterparts, and as they represent the "main battery" of a dock landing ship, the vessel needs to be designed around their parameters.

Actually, I think the German landing craft match up fairly closely in size to my own French landing craft. Mine are slightly smaller by several tons, but they do compare well, I thought. In the light landing craft, the difference is most profound - the French EA-13 is 65% the displacement of the German Sturm Landungsboot 40 (13 tons versus 20 tons). The French EDA-55 tank landing craft (55t) is 89% the displacement of the Pionier Landungsboot 40 (62t); and the French CDIC-200 is the same nominal displacement as the Marinefahrpram. Though the MFP is 23m longer than the CDIC-200 for that same displacement.

The Chileans don't match up as well - mostly because they've concentrated on building oceangoing, long-ranged types, and thus standardized on only two types of light craft.

Quoted

Originally posted by Brockpaine

Quoted

Originally posted by BruceDuncan
The current generation of German landing craft are rather larger than their foreign counterparts, and as they represent the "main battery" of a dock landing ship, the vessel needs to be designed around their parameters.

Actually, I think the German landing craft match up fairly closely in size to my own French landing craft. Mine are slightly smaller by several tons, but they do compare well, I thought. In the light landing craft, the difference is most profound - the French EA-13 is 65% the displacement of the German Sturm Landungsboot 40 (13 tons versus 20 tons). The French EDA-55 tank landing craft (55t) is 89% the displacement of the Pionier Landungsboot 40 (62t); and the French CDIC-200 is the same nominal displacement as the Marinefahrpram. Though the MFP is 23m longer than the CDIC-200 for that same displacement.

The Chileans don't match up as well - mostly because they've concentrated on building oceangoing, long-ranged types, and thus standardized on only two types of light craft.

Tonnage is less the determing factor than the dimensions of the craft in question. For example, a ship with a docking well of the Chateaurenault could carry only four PLB 40s, where the Wittelsback can accommodate six; that makes the difference between landing a squadron's worth of tanks in two waves instead of three. If necessary, it would possible to load several Marinefahrpram into the Wittelsbach's docking well; they could not be fitted into the docking well of a Chateaurenault.

That's true - I'm looking at displacement (where the types match up well), while you're looking at physical dimensions, which is where the German craft are much larger.

Quoted

Originally posted by Brockpaine
That's true - I'm looking at displacement (where the types match up well), while you're looking at physical dimensions, which is where the German craft are much larger.

And for the confined spaces of a docking well, dimensions count more than mass.

Interesting, very interesting to compare with some designs I've been playing with lately.

Quoted

Originally posted by parador
Can't wait to see a drawing of her

I fear you will have to wait a long time; I do not have the skill to draw such a vessel from scratch. ALVAMA might, but I do not.

But I can include a copy of the dimensioned sketch drawing of the USS Ashland, upon which I based the Wittelsbach design.



As you can see, the docking well runs nearly the entire length of the ship, allowing it to carry a very large number of small landing craft or amphibious vehicles. All the other characteristics of the ship appear to be subordinated to the need to carry the maximum number of landing craft - everything else - crew quarters, mess facilities, storage areas - are crammed into all available spaces.

The only thing I would question it that if the KM intends to operate over long oceanic ranges then the cramped conditions might not be ideal. Of course you've got the coverted merchants as bulk troop transports but even so 220 troops might find things get stuffy on a long voyage.

I don't know what KM messing/ sleeping standards are like. OTL they seemed in advance of the RN who stuck to the hammock until the 1950s. Will the soldiers be in bunks or hammocks?

Interesting thought, looking at that plan its not going to be long before someone extends the well further forward and invents a Ro-Ro vessel.

Quoted

Originally posted by Hood
The only thing I would question it that if the KM intends to operate over long oceanic ranges then the cramped conditions might not be ideal. Of course you've got the coverted merchants as bulk troop transports but even so 220 troops might find things get stuffy on a long voyage.

Given that the Ashland class design was successfully employed over oceanic ranges in the Pacific Theatre during the Second World War, I think that the design has sufficient habitability for its intended purposes. Certainly the facilties are not up to the standard of the Queen Mary, but should suffice for assault landings.

Quoted

Interesting thought, looking at that plan its not going to be long before someone extends the well further forward and invents a Ro-Ro vessel.

A roll-on/roll-off design would have far different characteristics. The docking well is in effect a single deck; to be efficient, a RoRo vessel would have several decks, and internal ramps to permit movement of vehicles from one deck to another.

The Ashlands though were a wartime design, they were not designed for peacetime operations but for defeating the Japanese Empire. Comfort was not an issue. Though of course with air con etc. that will improve things below decks for tropical use.

I was musing out loud on Ro-Ro, I feel we're getting close to that point when someone feels that such capability can be done, as you say such a ship would be larger with perhaps 3 vehicle decks. A kind of super-LST.

Quoted

Originally posted by Hood
The Ashlands though were a wartime design, they were not designed for peacetime operations but for defeating the Japanese Empire. Comfort was not an issue. Though of course with air con etc. that will improve things below decks for tropical use.

Wartime design they may have been, but they served admirably for years afterwards. Aboard a 1940s warship - any warship - I doubt if comfort was a design consideration for any navy.

Quoted

Originally posted by Hood
I was musing out loud on Ro-Ro, I feel we're getting close to that point when someone feels that such capability can be done, as you say such a ship would be larger with perhaps 3 vehicle decks. A kind of super-LST.

The Irish ferry Wolfe Tone and the Chilean sistership Puerto Eden are pretty close in concept to a Ro-Ro in that they've got a vehicle and cargo deck with drive-on capabilities. Since they're designed for areas with heavy seas, though, they lack the bow doors or ramp that a "super LST" would have. I've considered building something similar for the ferry to Corsica; perhaps now's the time to go for it.

The Chileans also use two ferries running to Chiloe - they are very similar in design to the Chilean Navy's mechanized landing ships.

So a Ro-Ro might not be too far off.

Conceptually a train ferry *is* a RoRo vessel, so the idea exists and can be made real. But like a train ferry, a RoRo vessel needs sufficient traffic to make it worth while, and the investment in short-side facilities. Or, if the vessel is to be independent of shore-side facilities, then the extra cost is tacked on to the construction costs.

In WW, where we happily can ignore that, designing a RoRo ship would be rather easy.

Quoted

Originally posted by BruceDuncan
Or, if the vessel is to be independent of shore-side facilities, then the extra cost is tacked on to the construction costs.

Right. For instance, the two Chilean ferries, Ancud and Castro, are basically designed the way they are because they're running back and forth between two undeveloped harbors. The ferry line needed something that could transfer cargo and vehicles without extensive cranes or other shore facilities.

Something that might not be obvious in RoRo ship design is ventilating the 'cargo' spaces so that the exhaust fumes of the vehicles aboard don't kill everyone aboard. Another is the dead load of vehicles on the deck - a small car is one thing, a 40-ton tank something else. The US built one of the first C-5 cargo ships as a tank carrier but there were so many changes involved with the design that they cancelled everything after the first vessel and she took far too long to complete.

FWIW, the OTL US merchant marine had several *large* ocean-going train ferries that were requisitioned and used as vehicle and aircraft ferries. Designed to carry fully loaded rail cars they had the facilities to load and unload heavy tanks and vehicles and were used as such in the Torch landings of 1942.

Large ocean going? Probably a bit bigger than this one, right?

...

ROFL!