given their raw materials crunch? and lack of design staff and experience it would seem logical to rebuild fleet starting with smaller ships. they gambled and lost on high pressure steam engines.
to contend with RN it seems Type '39 & Type '41 torpedo boats and improved light cruisers (with the hybrid propulsion system) would have been more logical and prudent path? they had the excellent 1920's torpedo boats and hard lessons from previous light cruisers?
Yep should have continued with diesel development instead of 'changing horse mid stream' with super heated steam plants. The more powerful V line diesel would have been ready by the late 1930s instead of mid-war. The big problem with diesels is they need big hulls to get enough propulsion horse power.
The 1930 Bremse had 28,000hp inline diesel on a 100m / 2000t hull. The top speed is 28knts? which limits this to escort boat role, maybe with torps - Flottentorpedoboot ? Clearly the hull form is closer to cruiser than destroyer. Range is listed at 9000nm @ 19 knots based on 285t diesel, but another source suggested cruise speed is 15knots.
The 1928 , AGS has 54-56,000hp inline diesels on a 187m/16,000t hull and speed is limited to 28.5 knots as well. Clearly bulges were added for torpedo defence, that also limited speed since the original hull design was 30knots. Designed from the start for speed with transom stern should allow speeds up to 30 knots. The range is listed at 10,000nm @ 19-20 knots on 2500t diesel. Great for a surfaceraider.
The improved M class cruisers planned to use the V line diesels instead of the inline diesels. A quad mount of these improved engines put out 35,500hp and two such mounts could have been installed on this 11,000t warship. The 90,000hp turbine plant was designed to achieve a speed of 36 knots , the same hull with 71,000hp diesel plant- should allow over 33 knots, which is fine for a cruiser. The 1500t fuel should allow 17,000nm @ 19 knots, excellent for surface raider.
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A diesel destroyer was also designed mid war originally planned for a quads of 12500hp V-line diesel plant driving the center shaft-plus another diesel on each side direct driving separate shafts. The space is 45m x 10m in a DD engine compartment. That’s 75,000hp on ~ 3700t warship, with a top speed of 36knots and an endurance of 6500nm @ 19knots
but these are all much larger than the GTB you are mentioning....but does supply large numbers of surface raiders.