3-shaft propulsion

Discussions about the history of the ship, technical details, etc.

Moderator: Bill Jurens

Byron Angel
Senior Member
Posts: 1038
Joined: Sun Mar 06, 2011 1:06 am

3-shaft propulsion

Post by Byron Angel » Sat Jul 27, 2019 8:55 pm

pasoleati wrote:
Sat Jul 27, 2019 8:03 pm
Does the book discuss why Germans adopted 3-shaft propulsion? In detail discussing pros and cons.
Interesting question ...
A quick peek into Groener ("Die Deutschen Kriegsschiffe 1815-1945") indicates that 3-shaft propulsion was a feature of German capital ship designs starting with the Kaiser Friedrich III class of pre-dreadnoughts dating back to 1895 (laying down of first ship in class). This trend appear to have continued (with the sole exception of Prinzregent Luitpold with 2-shafts) all the way to the Bismarck class. The post-Bismarck design projects (H, J, K, L, M, N) had 3-shaft diesel propulsion, while the later designs (H42, H43, H44) had 4-shafts.

The German WW1 battle-cruisers (all the way through the uncompleted Mackensen and Ersatz Yorck designs) featured 4-shaft propulsion.

The post-WW1 diesel powered "pocket battleships" (Graf Spee, Deutschland) featured two shafts. The WW2 era "light battleships" (Scharnhorst, Gneisenau) and the heavy cruisers (Bluecher, Hipper Prinz Eugen) all featured three shafts.


Byron

User avatar
Herr Nilsson
Senior Member
Posts: 1389
Joined: Thu Oct 21, 2004 11:19 am
Location: Germany

Re: Battleship Bismarck: A Design and Operational History

Post by Herr Nilsson » Mon Jul 29, 2019 7:17 am

IMHO the reason for a 3-shaft propulsion was simply the fact that it was sufficient for the required speed.
Regards

Marc

"Thank God we blow up and sink more easily." (unknown officer from HMS Norfolk)

RobertsonN
Member
Posts: 178
Joined: Wed Jan 05, 2011 9:47 am

Re: Battleship Bismarck: A Design and Operational History

Post by RobertsonN » Mon Jul 29, 2019 4:05 pm

Three shafts weigh less than four. Breyer in Marine Arsenal No. 2, p. 6, gives the weight of the shafts and propellers in Gneisenau as 366 mt. So one shaft with its propeller weighed about 120 mt,

Neil Robertson

User avatar
marcelo_malara
Senior Member
Posts: 1162
Joined: Sun Oct 02, 2005 11:14 pm
Location: buenos aires

Re: Battleship Bismarck: A Design and Operational History

Post by marcelo_malara » Mon Jul 29, 2019 4:44 pm

Why then cruisers had commonly four shafts when three or two would suffice for the power required?

Regards

User avatar
Herr Nilsson
Senior Member
Posts: 1389
Joined: Thu Oct 21, 2004 11:19 am
Location: Germany

Re: Battleship Bismarck: A Design and Operational History

Post by Herr Nilsson » Mon Jul 29, 2019 4:47 pm

What cruisers?
Regards

Marc

"Thank God we blow up and sink more easily." (unknown officer from HMS Norfolk)

User avatar
marcelo_malara
Senior Member
Posts: 1162
Joined: Sun Oct 02, 2005 11:14 pm
Location: buenos aires

Re: Battleship Bismarck: A Design and Operational History

Post by marcelo_malara » Mon Jul 29, 2019 5:31 pm

Brooklyn class for example, 100.000 hp could be achived with two shafts.

User avatar
Herr Nilsson
Senior Member
Posts: 1389
Joined: Thu Oct 21, 2004 11:19 am
Location: Germany

Re: Battleship Bismarck: A Design and Operational History

Post by Herr Nilsson » Mon Jul 29, 2019 5:55 pm

But Brooklyn wasn't a German warship. The German battlecruisers in WW I required 4 sets of propellers, shafts and turbines to be fast enough. Due to technological progress the German battleships of WW II required just 3 sets and were even faster.
Regards

Marc

"Thank God we blow up and sink more easily." (unknown officer from HMS Norfolk)

dunmunro
Senior Member
Posts: 3904
Joined: Sat Oct 22, 2005 1:25 am
Location: Langley BC Canada

Re: Battleship Bismarck: A Design and Operational History

Post by dunmunro » Mon Jul 29, 2019 6:34 pm

marcelo_malara wrote:
Mon Jul 29, 2019 5:31 pm
Brooklyn class for example, 100.000 hp could be achived with two shafts.
USS Brooklyn (CL-40) had 4 shafts.

pasoleati
Member
Posts: 21
Joined: Thu Jul 14, 2005 3:30 am
Location: Finland

Re: Battleship Bismarck: A Design and Operational History

Post by pasoleati » Mon Jul 29, 2019 7:46 pm

Does Herr Nilsson have primary sources to support his theory? After all, to be logical, Germans should have been world leaders in large warship propulsion engineering which I doubt as e.g. Whitley's books mention plenty of inefficiencies and serious reliability issues with German powerplants.

User avatar
Herr Nilsson
Senior Member
Posts: 1389
Joined: Thu Oct 21, 2004 11:19 am
Location: Germany

Re: Battleship Bismarck: A Design and Operational History

Post by Herr Nilsson » Mon Jul 29, 2019 8:19 pm

No, I don't have primary sources to support my theory, but in my experience ship building is always a weight saving issue.
Regards

Marc

"Thank God we blow up and sink more easily." (unknown officer from HMS Norfolk)

User avatar
marcelo_malara
Senior Member
Posts: 1162
Joined: Sun Oct 02, 2005 11:14 pm
Location: buenos aires

Re: Battleship Bismarck: A Design and Operational History

Post by marcelo_malara » Mon Jul 29, 2019 8:36 pm

I don´t agree, warships have others requirements besides hitting the required HP. As I said, most cruisers in WWII have four shafts for 80.000/100.000 hp, what would suffice with two shafts, but AFAIK the only power to go to two shafts in cruisers was Italy. Redundancy, internal subdivision, etc...was a necessity too.

German power plants were a case of engineering beyond reliability. German destroyers used very high pressure steam plants, 70 km/cm2, when other powers stayed around 40 kg/cm2. That advance came with a cost.

pasoleati
Member
Posts: 21
Joined: Thu Jul 14, 2005 3:30 am
Location: Finland

Re: Battleship Bismarck: A Design and Operational History

Post by pasoleati » Mon Jul 29, 2019 8:43 pm

And despite high pressures and temperatures, German powerplants weren't particularly fuel-efficient. Question is why not.

User avatar
marcelo_malara
Senior Member
Posts: 1162
Joined: Sun Oct 02, 2005 11:14 pm
Location: buenos aires

Re: Battleship Bismarck: A Design and Operational History

Post by marcelo_malara » Mon Jul 29, 2019 8:54 pm

pasoleati wrote:
Mon Jul 29, 2019 8:43 pm
And despite high pressures and temperatures, German powerplants weren't particularly fuel-efficient. Question is why not.
I didn´t know that. Do you have consumption numbers?

pasoleati
Member
Posts: 21
Joined: Thu Jul 14, 2005 3:30 am
Location: Finland

3-shaft propulsion 2

Post by pasoleati » Mon Jul 29, 2019 9:13 pm

No, as I don't have the books with me now. I do recall it being mentioned at least in Whitley that German marine steam plants were relatively inefficient.

User avatar
marcelo_malara
Senior Member
Posts: 1162
Joined: Sun Oct 02, 2005 11:14 pm
Location: buenos aires

Re: Battleship Bismarck: A Design and Operational History

Post by marcelo_malara » Mon Jul 29, 2019 10:23 pm

Oh I see it now in mine, German Destroyers, page 216, boiler system:

Wagner Large, design efficiency: 78%
Wagner Small, " : 78%
Benson, " : 77%
RN Admiralty, " : 76%

Don´t know exactly what this mean, I think is some sort of relation of the weight of effectively evaporated water to the theoretically maximum that a quantity of fuel can.

May be a more interesting number is the weight of the machinery, from 790 t to 860 t for 70.000 hp, Friedman quotes 600 t for 44.000 hp in the Tribals, for the same power the Geman machinery would weight about 500 t.

Post Reply