Shaft and rudder configuration in battleships

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Javier L.
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Shaft and rudder configuration in battleships

Postby Javier L. » Wed Dec 01, 2004 1:31 pm

Is there any particular reason why some battleships had only one rudder and others had 2 parallel rudders? I was thinking maybe it had to do with the number of shafts but the Iowas for example with 4 shafts have 2 parallel rudders and the Richelieu with the same number of shafts has only 1 rudder. Any advantage/disadvantage of having 1 or 2 rudders? How does it affect the ship's maneuvering?

Shaft and rudder configuration

Warspite: 4 shafts, 2 parallel rudders.
Littorio: 4 shafts, 2 parallel rudders.
Iowa: 4 shafts, 2 parallel rudders.

Hood: 4 shafts, 1 rudder.
Dunkerque: 4 shafts, 1 rudder.
Richelieu: 4 shafts, 1 rudder.
King George V: 4 shafts, 1 rudder.
Yamato: 4 shafts, 1 rudder.
Vanguard: 4 shafts, 1 rudder.

Scharnhorst: 3 shafts, 2 parallel rudders.
Bismarck: 3 shafts, 2 parallel rudders.

Rodney: 2 shafts, 1 rudder.

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Re: Shaft and rudder configuration in battleships

Postby Tiornu » Wed Dec 01, 2004 10:33 pm

One rudder was the norm (outside the RN) up until the 1930's. You'll see some ships (especially German ships) with a small auxiliary rudder forward of the main one. This was not a big success, and the only modern design I know with that arrangement was Yamato.
Littorio had one main rudder and two auxiliary rudders, but this pair was not mounted on the centerline, and it appears to have been a good system.
The British went to one main rudder with one auxiliary in the "R" class in hopes that separating them would decrease the chances that both would be crippled, but the auxiliary proved useless and was removed. It was also noted that twin rudders represented 3% of a ship's water resistance. Perhaps this explains why the British never went back to twin rudders.
Meanwhile, the US had gone the other direction and adopted twins for their new battleships.

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Postby ingura » Thu Dec 02, 2004 7:47 am

Although the Twins and BISMARCK were both having 3 shafts and 2 parallel rudders, the effect was very different.

The Twins did have problems with this arrangement - very slow reactions
BISMARCK and TIRPITZ were very reactive even at 5° rudder-angle - which causes problems too (if the rudder is blocked :stubborn: )

Peter.

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Javier L.
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Re: Shaft and rudder configuration in battleships

Postby Javier L. » Fri Dec 03, 2004 1:28 am

Tiornu wrote: It was also noted that twin rudders represented 3% of a ship's water resistance. Perhaps this explains why the British never went back to twin rudders.

Can we say then that if the Iowas for example had been given only one rudder in the certerline the ships would be even faster? Perhaps two rudders offer more resistance but single rudders are usually larger too.

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Re: Shaft and rudder configuration in battleships

Postby Tiornu » Fri Dec 03, 2004 7:11 am

I guess they would have been marginally faster with one rudder, and marginally faster than that with no rudders...!
You'll probably get more intelligent commentary from someone with ship design experience.

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Postby foeth » Sat Dec 04, 2004 5:42 pm

I guess they would have been marginally faster with one rudder, and marginally faster than that with no rudders...!

Nope, a rudder in the propeller slipstream can recover rotational losses (acting as a stator) which are greater than it's own friction (even in the slipstream). It's not much though.

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Shaft and Rudder Configuration in Battleships

Postby dgrubb64 » Sun Dec 05, 2004 9:59 pm

The effects of the rudders have on the ship becomes even more confusing when you consider that the Bismarck/Tirpitz and the Scharnhorst/Gniesenau both had angled rudders and angled prop shafts i.e the rudders were not vertical and the wing shafts were not parallel to the centreline of the ship (they angles out at about 3 degrees? I think)

I have tried the non vertical rudders on a 6ft model Bismarck after trying the same two rudders hanging vertically and it does make a difference, the model does not heel so much in a high speed turn with the non vertical rudders as it does with the vertical rudders. I wonder if this would hold for the real ship.

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Javier L.
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Postby Javier L. » Sun Dec 05, 2004 10:29 pm

Interesting. Are the rudders in the Iowa Class battleships inclined too, or are they vertical? What about other battleships?

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shaft and rudder configuration in battleships

Postby dgrubb64 » Wed Dec 08, 2004 9:41 pm

As far as I know the Germans were the only navy to use inclined / angled radders in their capital ships

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Turning radius

Postby José M. Rico » Mon Dec 13, 2004 8:52 am

Turning radius of a 3-shaft German battleship (Gneisenau) with the rudders hard to port/starboard at different speeds.

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Postby Bgile » Tue Mar 15, 2005 1:48 am

Long outboard shaft runs were a weakness in torpedo protective systems.

I don’t know if it was a design consideration, but the German ships with 3 shafts reduced this problem to a great degree. All three engine rooms are grouped together, making for short outboard shaft runs. The weakess in that is of course the possibility of all 3 engine rooms becoming disabled by one hit.


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