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Advance and Tactical Radius


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#1 MatthewB

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Posted 15 September 2015 - 08:56 AM

I have been talking with a friend in the Netherlands who works at a Naval Simulation facility, where they do work on modeling performance for Naval Architects, and the various EU Navies.

And we got around to talking about things like Advance and Tactical Turning Radii.

I mentioned this game, and how it include the Advance, as a general 500yd distance that ships must move before executing a turn, and he said that was probably a pretty accurate figure for most of the ships at the time, but that it could be incredibly short, or incredibly long for some ships at some speeds.

The conversation basically brought up, as is mentioned in the rules, that some ships tend to have a harder time turning (larger radius) due to having a high Length:Beam ratio. The Higher this number, the greater their turning radius.

But he pointed out that Advance was tied to this ratio in the same fashion: That a higher L:B Ratio led to a longer advance.

We did some basic simulations on the software he had (well, he did them, I dug up the numbers to plug in), and found that many bigger ships (CA - BB) would actually have a short advance at most speeds below flank, while smaller ships could have as much as a 50% longer advance (especially the IJN's Larger DDs and Smaller CLs).

Also brought up was that these ships (with high L:B Ratios) tended to have a turning radius that collapsed faster (the ships lost speed faster than larger ships, resulting it the turning radius shrinking, along with the Transfer).

So that a Japanese Nagara-class CL, or Akizuki-class DD might have a 25% smaller turning radius after 90% than would a larger ships, such as the Agano, or Kager
ō or Fubuki, of the same classes (CL or DD).

For the BBs, the Averages given for Advance and Turning Radius tended to work out all pretty similar.

But has anyone given any thought to working out the Advance and Turning radius of the different ships?

​The differences in maneuvering characteristics were one of the major reasons that disorganization during night battles was so severe and dangerous.

MB



#2 Cpt M

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Posted 15 September 2015 - 07:39 PM

While the turning radius of each ship class could vary considerably (for example, the South Dakota class BBs had a smaller turning radius than the Fletcher class DDs), the key element to keep in mind is requirement to have each ship maneuver in a similar fashion when operating in formation.  Standard doctrine for all navies was to use a set tactical diameter so that the movements could be keep as predictable as possible.  Consequently, the individual turning characteristics of each ship is less important than the actual maneuver and formation doctrine.  



#3 MatthewB

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Posted 16 September 2015 - 04:54 PM

I am currently reading the Navy Doctrines established during WWII, and their WWI Naval Battle Instructions (which are kind of blind).

The reasoning behind this was that often Destroyers, or ships that have disengaged, might not be forced to adhere so closely to what the main battle-line was doing.

While I did not stop to consider the need for formation keeping, the reading of the accounts of the various battles in the Pacific (I have not yet read much about the Atlantic) show that often Destroyers would operate independently of the main forces (CAs, mostly, in the cases I am reading).

But your post, and the reading of the various academic works on the subject1 have led me to think that even with their being a typical Tactical Turning radius, there are instances where it might be necessary to have different turning radii.

While it is tremendously convenient to have a turning radius and a game-scale (ground/ocean and time) whereby one compass-point through a turn ≈ 100yds, it looks as though different navies tended to have different Tactical Turning Radii.

The USN and RN both used 500 yards, but the IJN and KMS tended to use 500 meters as their typical tactical turning radius. And all recognized different (larger) turning radii for different navigational requirements (typically 750yds and 1000yrds).

So, I understand the desire to keep the simplicity and ease of play.

But... I also look at the IJN Doctrine of having the DD Divisions (and their CL leaders) operate by a different Tactical Maneuver Doctrine than the heavier forces of their CAs and BBs (The IJN was a little insane, though, due to their obsession with the 1905 Tsushima victory over the Russian Navy. This tended to make their Naval thinking more than a little imbalanced).

In any event, I am creating a 750yd and 1000yd turning radius template so they will be available for those who wish to make use of them.

I am still learning about the vagaries of Naval Warfare in this period. It is much more constrained than in earlier periods prior to the Navies concerned applying more doctrinal standards to their forces. Seakeeping has tended to remain a concern, but the ideas tended to shift as new blood entered the different navies.

MB


1 Sources:

Hone, T. Building a Doctrine: U.S. Naval Tactics and Battle Plans in the Interwar Period. International Journal of Naval History. vol 1, no. 2. Oct, 2002

Dickson, W.D. Battleship and Cruiser Doctrine, IJN. (Original Publication source currently not available)

 

MDART.FOW. A Tale of Two Doctrines: Japanese and American Surface Warfare Doctrine, 1941 - 1943. (Original Publication Source and Author currently not available)






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