1934-1936 German Raider competition: Ardanian AU

[Obsydian Shade]

To all German shipbuilding firms:

It is the consensus of the General Staff that a war with Great Britain is practically inevitable within the next decade. Being an island nation, the UK is a natural fortress that cannot be taken in traditional land offensive, meaning it must instead be starved into submission, via a naval and air campaign. Unfortunately, in the time available to us, we cannot match the strength of the of the Royal Navy, so must concentrate our available resources on destroying British mercantile shipping. Much of this will be accomplished by U-boats and aircraft, but the Reichsmarine is in agreement that a surface component is also needed. Regrettably, large, powerful vessels aren't an option, as these will be too easily countered by the numerically superior Royal Navy. Instead, a new type of vessel is required, a pure raider designed for no other purpose.

Besides having the speed and range required for lengthy operations on the high seas, such a vessel must be inexpensive enough to be built in the required numbers. This means sacrificing such things as armor, complex fire control arrangements, and limiting main armament to produce a reasonably cost effective design that won't tie down too many resources needed elsewhere.
With regard to speed and range, a 39-40 knot top speed is required to ensure being able outrun any RN cruiser by a comfortable margin, while a minimal range of 20,000 nm @ 17kts will be needed for this type of work. All of this needs to go on a hull displacing no more than 3-4,000 tons standard.

Main armament should be sufficient for fending off destroyers, and sinking merchant vessels, but not so heavy as to encourage ship captains to fight when they should run, particularly against enemy cruisers. To this end, an armament of 4x150mm guns in either four single mounts or two twin turrets is judged sufficient for the task. Torpedoes in either twin or quadruple mounts are also considered essential, and provisions for underwater or otherwise concealed tubes should be given consideration. AA armament needs to be sufficient for fending off aerial attack, so at least a moderate suite is required.

Lastly. due consideration should be given to either A: providing some means by which the unit can disguise itself as a merchant ship, preferably being able to appear as a number of different vessels by means of easily erected screens , and dummy funnels and masts, or B: If the latter option is judged impracticable, then reducing visibility via lowering the raider's silhouette, eschewing features such as tall aerial masts or fire control towers. Any measure which will aid in slipping through the British blockade will contribute heavily to the success and survival of the unit!

The initial order will be for 6-12 vessels, and if successful, The Reichsmarine is prepared to look at putting the design into as high production as machinery output will allow for.

[Thiel]

You requirements seems a tad self contradictory. 40kts of speed, 20k nm range at a fairly substantial speed and cheap doesn't mix.

[acelanceloet]

I'm with Thiel here.

If I look at my ship reference list, even for destroyers it was uncommon to go over 35 knots. The dutch Gerhard Callenburgh went 37,5 and had a range of 5400 NM at 19 knots. She required 33,6 MW for that. The mutch bigger Fletcher class could reach over 36 knots on 44,7 MW but had a range of 6500 NM at 12 knots. The only thing which approaches your numbers when looking at (relatively cheap, buildable in numbers) destroyers, is the seahawk concepts of 1965+.

When looking at ships which go over 30 knots, We find cruisers like the Cleveland class. The cleveland reached 32 knots and had a range of 11000 NM at 15 knots.

In other words, if you build a cleveland class hull without armour but with more machinery and fuel and less armour........ You will have about what you are proposing. The cost of such a ship will still be about that of an cruiser, although with only three quarters of its crew. Is that what you want from this challenge, because otherwise I would look at modifying the requirements a bit.

Also, I know of no German shipbuilding firms on shipbucket It might be better to introduce a bit what and who you want in this challenge

[Thiel]

Also, I know of no German shipbuilding firms on shipbucket It might be better to introduce a bit what and who you want in this challenge

Presumably it's because he/she wants German styled ships.
Which might be a problem depending on how much the AU in question deviates from reality because inter war Germany had fuck-all in terms of naval design capacity.

[erik_t]

You requirements seems a tad self contradictory. 40kts of speed, 20k nm range at a fairly substantial speed and cheap doesn't mix.

To say the least. I'm somewhat skeptical the requirements could be met even with today's technology without heroic application of cash.

[Thiel]

I suppose some sort of hybrid catamaran/surface effect ship could do it.
Cruise as a catamaran, deploy skirt/ramp and sprint on surface effect.
It would be a beast of a machine that much is certain.

[Novice]

I'm no engineer, and have no knowledge of the power requirement to achieve the top speed specified. At the start of WW2 the longest range was achieved by using Diesels, which were heavy and expensive, and needed well trained mechanics. For high speed you needed turbines. As our more knowledgeable friends above mentioned you need at least 1,500 tons hull to accommodate the required engines, but such a hull doesn't go well with 150 mm guns, as Germany's Z-39 class illustrates, and they were like 2,300 tons at least.

[Charguizard]

I had prepared some designs roughly based on our previous discussions. I'll be drawing off of the one that most closely resembles the requirements, which incidentally is the smallest one.
It's nowhere near as well performing as the requirements, but it's something.
SS report here: https://pastebin.com/xsQRZPJm
By forcing the machinery it could probably do 36 kt in good weather and 37 on trials as SS is notoriously conservative with high speed ships. Also I intend it to be able to tender subs operating far from bases.

[Thiel]

If you're going to play sub tender you're going to need more misc weight for stores and gear and way more fuel.

[Obsydian Shade]

It might be possible to reduce range a bit, but I'm basing my design requirements off the later British Abdiel Class minelayers, which displaced something like 2,650 or so tons. I'm allowing for up to 4,000 tons, so that should offer enough leeway.

As far as the design being cheap, it's more like cheap as possible under the design requirements. As far as the AU goes, feel free to read my thoughts on the Ardannian AU in the relevant section.