Deutschland class upgraded

This is an amateurs questions within naval engineering, but here it comes:
In a scenario were everything does not turn desperate as soon as IOTL, lets assume that Germany wants to make a Z plan light version and create a couple of task forces centered around say Scharnhorst/Gneisenau/Zeppelin and Bismarck/Tirpitz/Peter Strasser or alternatively S. Speed of such a force would be 30+ knots and while the Hippers could keep up if their boilers didn't blow up its pretty clear that the Deutschlands, for all their marathon legs is a vulnerability at 28 knots top speed.
Could they be upgraded to increase their speed? I am thinking lengthen stern and bow and extra boilers and/or skipping some of the diesels for extra boilers, but what do I know?
Could this be done in a 1-2 year operation costing less than building a new ship?
And while we are at it, if S&G gets the 38 cm guns in the same scenario, could the Deutsclands be fitted with the improved SK C/34 rather than their SK C/28?

Replacing the diesels with conventional turbines would probably allow for an increase in speed (and reliability) at the expense of endurance. Upgrading the guns in such an extensive reconstruction would make sense, since the newer model had better armour penetration. There would probably be improvements to the AA armament.

The real question would be wether the cost, and more critically the use of limited yard cability, woul be justified, since the combat value of the ships wouldn't be much improved.

Those diesels also weighed less, and took up less volume than a geared turbine and boiler setup, besides the economy.

You just cant fit 32 knots, 10,000 mile range(at the high 23 knot cruise speed), plus 11 inch guns and armor on 11,000 tons with Steam

marathag said:

Those diesels also weighed less, and took up less volume than a geared turbine and boiler setup, besides the economy.

You just cant fit 32 knots, 10,000 mile range(at the high 23 knot cruise speed), plus 11 inch guns and armor on 11,000 tons with Steam

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I realize there will be drawbacks and the Graf Spee was already well designed for range.

Gneisenau had 31 knots and 6000 nautical miles range at 19 knots. So there is some range to trade if you magine them raiding together or in task forces.

That kind of rebuild basically amounts to jacking up the ship's bell and inserting a new ship underneath. Speed is very expensive to add - you'd be looking at considerably more power, needing a total rebuild of the midsection - possibly adding a hull plug, if there's no parallel midbody you've had it - as well as lengthening the bow and stern to fine out the hull. End result - a very expensive ship of limited utility. It can be done, probably, but it's a big job and really not worth it. Build an equal number of Kreuzer P hulls instead. Not much better tactically, but hardly any more expensive and significantly less worn out.

Does this in anyway improve the Germans' chances of executing OPERATION PINNIPED?

Just kidding, couldn't resist!!!!

Gudestein said:

1 Could they be upgraded to increase their speed? I am thinking lengthen stern and bow and extra boilers and/or skipping some of the diesels for extra boilers, but what do I know?

2 Could this be done in a 1-2 year operation costing less than building a new ship?

3 And while we are at it, if S&G gets the 38 cm guns in the same scenario, could the Deutsclands be fitted with the improved SK C/34 rather than their SK C/28?

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3 yes but very expensive and adds weight and makes you only have 4 main guns so ranging anything be very hard (with salvo's).

2 I think 2+ even in peacetime.

1 expensive and hard to do.

When you add them together you may as well buy a new ship main guns/mounts and new engines and hull modifications will cost a very large chunk of a new ship (IMO more than 60%) so you may as well just buy a 2nd ship (unless treaty limited) and you get to keep the first one as well.

jsb said:

3 yes but very expensive and adds weight and makes you only have 4 main guns so ranging anything be very hard (with salvo's).

2 I think 2+ even in peacetime.

1 expensive and hard to do.

When you add them together you may as well buy a new ship main guns/mounts and new engines and hull modifications will cost a very large chunk of a new ship (IMO more than 60%) so you may as well just buy a 2nd ship (unless treaty limited) and you get to keep the first one as well.

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I got a feeling it would not be easy. However, I was talking about the 3x28 cm's used on S&G. Quicker firing and with much improved penetration.

Zheng He said:

Does this in anyway improve the Germans' chances of executing OPERATION PINNIPED?

Just kidding, couldn't resist!!!!

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You just know that's where he's going...

SO just playing with the thought a little. As far as I got it, the main advantage of the diesels were range and their drawback was weight. If we simply say out with he diesels and install boilers and turbines instead?
Its only 2-3 knots to the 31 knot target.

A replacement has been done on a battleship before:
http://en.wikipedia.org/wiki/USS_Texas_(BB-35)

Gudestein said:

SO just playing with the thought a little. As far as I got it, the main advantage of the diesels were range and their drawback was weight. If we simply say out with he diesels and install boilers and turbines instead?
Its only 2-3 knots to the 31 knot target.

A replacement has been done on a battleship before:
http://en.wikipedia.org/wiki/USS_Texas_(BB-35)

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It's only 2-3 knots... sure. But that 2-3 knots may well take a doubling of SHP. And there's always the risk of resonances, vortices (the three-shaft layout the Kriegsmarine used royally sucks, with the worst sides of the single-shaft and twin-shaft designs)...

HMS Tiger had 85,000 SHP and managed 28 knots. HMS Renown, same displacement but a longer and therefore more efficient design, did 31 knots on 112,000 SHP - about a 30% increase, on a ship that was also more efficient. Courageous was even longer, much lighter, and had 90,000 SHP installed - and did 32 knots.

Basically a ship has to be long, narrow and very powerful to break 30 knots.

Gudestein said:

I got a feeling it would not be easy. However, I was talking about the 3x28 cm's used on S&G. Quicker firing and with much improved penetration.

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sorry got thinking about 15' twins,

You are still talking about [FONT=Arial,Helvetica]750t v 600t per turret (and per gun [/FONT][FONT=Arial,Helvetica]53,250 kg v [/FONT][FONT=Arial,Helvetica]48,200 kg) will not happen without hull changes to support it 300t (not sure how much of that is thicker protection) high up on deck is a lot. [/FONT]

The Panzerschiffs had eight diesel engines geared to two shafts, and staggered forward and aft of the hull.
A classic is to try to rebuild them with sixteen engines geared to four shafts, in a enlarged version. The cube law* gives them 32 knots, but I would take that as a (very) gross approximation.
*new speed is equal to old speed multiplied by the cube root of the new power divided by the old one. 32=26x1'2599 (cube root of two)

Generally, any rebuild is possible within the constraints of the hull. However, you have to look at what is cost effective. Getting an extra 2-3 knots and newer 11 inchers is probably not worth either the expense of the yard time that could be devoted to another project. It is just not that bigger an increase in combat potential vs time and expense.

Ramontxo said:

The Panzerschiffs had eight diesel engines geared to two shafts, and staggered forward and aft of the hull.
A classic is to try to rebuild them with sixteen engines geared to four shafts, in a enlarged version. The cube law* gives them 32 knots, but I would take that as a (very) gross approximation.
*new speed is equal to old speed multiplied by the cube root of the new power divided by the old one. 32=26x1'2599 (cube root of two)

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Thanks, nice to have some qualified basis to approximate from. Unfortunately, twice the power would give more weight.
I am guessing this line of thought will die out.

johnboy said:

Generally, any rebuild is possible within the constraints of the hull. However, you have to look at what is cost effective. Getting an extra 2-3 knots and newer 11 inchers is probably not worth either the expense of the yard time that could be devoted to another project. It is just not that bigger an increase in combat potential vs time and expense.

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I think the conclusion is right, but its not a small difference to be caught vs. not to be caught.

Im with the Majority here

Don't bother basically - use the resorces and money to build more Hipper type Heavy Cruisers (or finish the ones that had been started!)

The Deutschland "Panzershiffe" Heavy Cruisers were a compromise design - trying to build a ship that could outgun an 8" Cruiser within the resources, ship building skills and 'limits' then allowed to Germany by international treaty.

The problem is that by 1937 a Town Class Light Cruiser has more armor, is still probably faster than any refitted Panzershiffe is likely to be, and its 6" guns are a threat to the Deutschland while the Deutschlands guns are already a threat to the Towns and virtually no threat to any British capital ship even with an upgraded so no point in improving them.

Seems like an awful lot of effort for very little gain

As for the Twins - they could certainly be upgraded with the twin 15" (I understand that this was always a planned future upgrade) but this would take them out of circulation for the period of refit and inevitable teething issues/post refit work up.

For me the 2 ships were more valuable as a 'fleet in being' as a potential threat to allied convoys tying down Royal Navy home fleet assets (which was calculated as 2 for 1) - not going to be doing this as well if 1 or both are conducting a lengthy refit.

Again I would have poured resources into other ships / war industries

not convinced it would be worth the effort but possible to adopt 8" guns used on Admiral Hipper class for weight savings? and was more modern design.

and 24-cylinder diesels used on (mooted) destroyer project http://german-navy.de/kriegsmarine/ships/destroyer/zerstorer1944/tech.html

(same number of shafts and engines in smaller hull so , as layman, would imagine it's possible?)

Navally the main challenge for Germany is not to "piss off" Britain too early.

If say Germany announce ambitious naval plans in 1935 instead of the Anglo-German naval treaty of 1935 the British tolerance towards Hitler will drop dramatically. So if Hitler order a re-militarization of the Rhineland as in OTL the French will be supported in "re-instating order" - i.e. no more nazis.

If Hitler does nothing, he will just be seen as a wimp inside Germany and probably won't last long.

By 1938 the British were pissed off anyway and initiated the biggest naval rearmament in British history, but don't do anything before Anschluss and Munich.

Rebuilding some pocket battleships can of course be seen as only a minor project, but I'm sure the British would be VERY concerned if they loose their speed advantage over the Deutschlands.

In such a world of political constraints the ideal solutions are however not allways the technically or economically best - IOW a comprehensive reconstruction might be easier to conceal the right contense of than new construction.

The question still remains however if a faster ship with less range really was what Germany needed? Germany had no realistic chance of challenging British naval superiority, but with their big range the Deutschlands were a serious threat to British trade and communications worldwide - for a very modest expense. A fast short ranged ship would be a potential nuisance in the North Sea and the North Atlantic - but not enough to seriously challenge British rule of the seas. In fact it would allow a lot of British cruises to be focussed at hotspots instead of being dispersed in hunting groups in the Atlantic and IO.

You mention a scenario where Germany go for a renewed Plan Z. I guess that could be after a Barbarossa, where the USSR actually collapse just after the door is kicked in (however likely that is). In such a scenario Germany would need a fleet to seriously challenge the RN on all counts. But even here the OTL Deutschlands would appear better as they were to divert the RN cruisers and the ships needed for the main fleet action probably could be built better, faster and cheaper from scratch.

While armament improvement is always handy, in this case its quite unnecesseary - as far as i remember, the new 28cm guns performed better against heavy - battleship - armor, and slightly worse against light - destroyer, cruiser - armor, so... what for?

And again, 3 knots again always welcome, but at what cost? Smaller range, long time in the yard, money and maybe reliability issues...

With hindsight, the class was as good as it was, the Scheer did a really impressive patrol (and if Langsdorff did not fuck up, the GS would have an impressive one too IMHO), and IMHO after 41 at latest, the surface raiding sorties would have been out of question with or without the speed and gun improvement anyway - long story short: not worth it.