From the Washington Naval Treaty to the end of the Second World War.
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Steve Crandell wrote:Interesting ideas and a number of reasons for reduced propulsion power.
However, I don't understand why it would be necessary to reduce speed to retain steerage. Ever. The faster you go, the more effective a given rudder is at maintaining course, right?
A lot of that is dependent upon rudder location. Typically rudders are placed behind the screws to enhance flow and turning rates at low speed.
If I had to guess they were having lubrication cooling issues, turbine over-speed trips, problems maintaining condenser vacuum (those things have to be drained and cleaned several times a year, tube by tube, x many thousands) or a steam line rupture. The steam line would be one of the more hairy situations as you'd have to shut off the main steam stops out of the boilers until you figure exactly what systems are damaged and what cross-connect line-ups are still viable. This was probably the worst case engineering scenario we had. Super-heated steam pouring into confined spaces...
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Some may not be aware of Scharnhorst's history of machinery and steam systems failures through out its career. Gneisenau was not plagued with these recurring defects.
During the encounter with Renown on April 9 1940:
The number 1 and 3 boiler rooms developed problems that caused the shut down of the starboard turbine, reducing speed to 22 knots. ( a loss of steam supply to the starboard turbine is given as the initial cause of the speed loss to 22 knots at N Cape)
After about 15 minutes Shcarnhorst was able to make 26 knots.
But after about 15 more minutes the starboard turbine had to be shut down once more. This time speed was reduced to 15 knots for several minutes. During the next 40 minutes Scharnhorst gradually worked up speed to 25 knots. After that the Scharnhorst was making more more speed than Renown which had worked up to 29 knots as the Scharnhorst continued to pull away.
During operation Berlin from Jan/22/1941 to mid March 1941, the Scharnhorst encountered several problems with defective boiler tubes. It could not sustain high speeds. Gneisenau did not exhibit these problems. During its time at Brest France, ten weeks were expended in overhauling the steam systems and specifically in replacing boiler tubes.
During the Channel Dash the emergency shut down valves were tripped when Scharnhorst ran over a magnetic mine. It was about 20 minutes before one turbine was returned to operation, then several more minutes before the other two were also brought back on line. Setting off a second mine close to the dutch coast also caused the shut down of two turbines. The third turbine was also shut down for a short period before Scharnhorst limped into port on the center turbine.
During trial in the Baltic during the Summer of 1942, the boiler tubes failed sending the Scharnhorst back to dry dock for several weeks. Following another stint in dock after a collision with a U-boat some sources describe Scharnhorst having continued problems with boiler tubes and turbines through the remainder of 1942. I recall Antonio has commented in these forums, that the defects were actually not properly put right before Scharnhorst transferred to Norway.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.