# Talk:New Mexico-class battleship

On January 22, 2008, I identified the the turbo-electric drive ship of the this class as being the New Mexico. JBickley00 (talk) 20:00, 22 January 2008 (UTC)

Not sure if I should have added inline "clarification needed", but need it for the sentence "The General Board arguing that the increasing range" in Design History section.Trilotat (talk) 13:52, 21 April 2017 (UTC)

My father, Roy P Moody, was a Chief Petty Officer [CSK] aboard the USS New Mexico from September 1940 to March 1945.  He always recalled to his family that the New Mexico sailed from Pearl Harbor the week before Japan's attack, missing it by only a few days.  This particular recollection has been independently corroborated by a source who is a family member of another former Naval crewman that also served aboard the USS New Mexico during the same month of December 1941.
2600:1700:96D0:A390:94AD:2A1:E7DC:4B55 (talk) 01:12, 1 July 2020 (UTC)Phoebe H Moody
Source: Roy Polk Moody, Chief Petty Officer [CSK], USS New Mexico, 1940-1945

Hate to break it to you, but your dad was mistaken. All three New Mexicos were on neutrality patrols in the Atlantic at the time. See Cressman's Official Chronology and DANFS. Parsecboy (talk) 10:22, 1 July 2020 (UTC)
That might be the USS Colorado instead of the USS New Mexico. 67.199.215.79 (talk) 22:58, 28 May 2024 (UTC)
It's a possibility, but according to DANFS, Colorado had left Pearl in June 1941 for the refit, quite a bit more than the few days in the story. The only other alternatives were the two New Yorks, but they were both on Neutrality Patrols as well. Methinks dad was spinning a yarn. Parsecboy (talk) 23:07, 28 May 2024 (UTC)

Does anybody know what kind of fire control system these ships had ? I suppose it consisted of a rangefinder and a director but which exactly ? Mr.Lovecraft (talk) 16:47, 30 January 2023 (UTC)

Start of the fifth Paragraph in the Design section, the sentence reads: "Despite the fact that the offer period had opened, one more major change to the design was made. At the time, the standard propulsion system for warships relied on steam turbines to turn propeller shafts, though the former operated most efficiently at high speed, while the latter generated thrust most effectively at relatively low speed."...  So it talks about two propulsion systems, one efficient at high speed and one efficient at low speed, and it mentions steam turbines, but it doesn't seem to mention another propulsion system.  Presumably the turbine is efficient at high speed, what propulsion system is efficient at low speed?Fanccr (talk) 04:26, 19 October 2023 (UTC)

It's not incomplete - turbines are most efficient at high RPM, while the propellers are most efficient at low RPM. If there's a rewording that makes that clearer, I'm open to ideas, but it makes sense to me as written (because I'm the one who wrote it, of course). Parsecboy (talk) 13:50, 19 October 2023 (UTC)
I could be wrong...  but that's like translating something that says that gasoline engines are efficient at high rpm and diesel engines are efficient at low rpm, to saying different car engines are efficient at high or low rpm, such as gasoline and wheels...  Do you see?  So, like...  there are propellers, and you can design propellers in different ways, one of the great advancements later in shipbuilding was the development of variable pitch propellers.  VPP sort of turned the propeller into the transmission of the ship, so you could hook a power source, such as a turbine, or diesel engine or triple expansion engine directly to a propeller, then run the power source in it's peak efficiency band, and the propeller itself would operate as the transmission, so if you wanted to slow down, you might change the pitch of the propeller to move less water or vice a versa.  Turbines spin at very high rpm, say, 10,000 rpm...  ship screws move very slowly.  It's quite difficult to efficiently reduce a 10,000 rpm turbine power source, to say, 50 rpm of a slow propeller.  Also, turbines are most efficient at between 50-100% throttle corresponding presumably to 50-100% rpm, so, say, 5,000-10,000 rpm.  So a top screw rpm, looking at iowa might be 200rpm, with just an arbitrary turbine top speed of 10krpm you'd want a 50:1 reduction gearing.  At low speed the propeller may rotate at, say, 50 rpm or lower, then the turbine would be rotating at 2,500 rpm, it would be outside it's efficiency range...  Now, a diesel engine on the other hand would probably be more efficient at low RPM.  I don't think a diesel engine's efficiency band includes 100% rpm.  It looks like diesel is efficient at roughly 1,800...  if you sped it up to 3000 rpm it would be out of it's power band.  I don't know anything about triple expansion engines or other options.Fanccr (talk) 14:11, 19 October 2023 (UTC)
Looking at https://www.navalgazing.net/Engineering-Part-3 it might actually be that, comparing the traditional (well, since dreadnought) geared turbine to turbo electric turbine, geared turbine needs a low pressure turbine and a high pressure turbine.  Presumably the LP turbine is efficient at low speed the HP turbine is efficient at high speed, so combining an LP+HP turbine with a geared turbine you have a working efficient system.  This contrasts to a turbo-electric system that only needs a single turbine rather than two turbines, but then uses the turbo electric propulsion system rather than the geared system...  So it looks like that would mean the propeller shaft would be driven by electric motor(s) powered by turbines without the need for having both high and low pressure turbines.  Not sure the best way to present that in an article though.Fanccr (talk) 14:19, 19 October 2023 (UTC)
I don't see, because it doesn't say anything about multiple engine systems. As for geared turbines, those had only been adopted for USS Nevada (BB-36), which was still under construction at the time design work on these ships was happening - everything up to then had used direct drive turbines (and the turbo-electric drive was only adopted for New Mexico—Mississippi and Idaho got direct drive turbines as well). I suppose the simplest solution is to just drop the "former/latter" construction if at the cost of a bit of repetition. Parsecboy (talk) 16:01, 19 October 2023 (UTC)
You could say that the need for greater endurance, required by the long distances inherent in operating in the Pacific ocean,  necessitated greater fuel efficiency which forced the designers to shift from the simple direct reduction turbine to a geared turbine design.  Geared turbines require a duplication of turbines. Geared turbines have a high pressure turbine and a low pressure turbine.  This duplication delivers greater fuel efficiency and in turn greater range and endurance by allowing the turbines to operate at efficient rotational speeds.  The navy experimented on this class with turbo electric propulsion which combined a turbine, with an electric motor which interfaced with the prop shaft, eliminating the need for duplication of turbines (hi/lo), as well as reduction gearing entirely.  Ultimately the navy would later abandon this and return to geared turbines.  It also removed the need for clutches.  Or something like that with appropriate references`Fanccr (talk) Fanccr (talk) 17:01, 19 October 2023 (UTC)