Quote:
Aspect ratio is not a legitimate targeting tool, especially for fleet boats. Not once in the entire war can I find a single instance of using aspect ratio or timing the length of the target by the wire. Both of these techniques enjoy a peculiar popularity here at Subsim and both are illegitimate techniques when applied to World War II submarines. As I said earlier, very rarely, U-Boats used aspect ratio as a last resort tool.
After-war analysis of targets sunk and not sunk by American submarines revealed that most of the time targets were misidentified. That means that if they had Capn Scurvy's perfect list of hull lengths, heights of all features and Hitman's aspect ratios, they still couldn't have hit the broad side of a barn.
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RR is mostly right. The aspect ratio and fixed wire methods are not, by any means, historically correct for the us submarines, and in the german uboats were they come from they also weren't that much used.
In the us submarines, plotting was the main way of getting the necessary values for the firing solution. Plot was fed from periscope observations (stadimeter for distance, based on mast/funnel heigth estimates and AOB by plain eye observation) and then checked against the TDC position keeper. When radar appeared, this task was greatly improved in accurancy, because the distance could be accurately determined, but overall the method was still the same, only more precise. Developed in the interwar period, when submarines were thought vulnerable if close to the target, the method ensured that even long range shots could have accurancy, and that firing even without seeing the target was possible (Thanks to the position keeper).
The german uboats in turn resorted to other systems, and the plot was mostly unused. The only time when something similar was used was when overhauling in the surface a target, be it a convoy or a single ship. In those cases, the captain would rely to the navigator a crude estimation of distance and issue the proper orders to keep the uboat in paralell course beyond the horizon. The comparison of own uboat course changes and bearing lines gave the navigator an approximate idea of the enemy course and speed. And when in perfect paralell position, the commander would make some speed variations until the bearing stayed constant, showing true enemy speed. In other circunstances, mainly night and submerged attacks, the commander or IWO estimated all, distance, AOB and speed by naked eye, and if available, used the values gathered previously during the overhaul maneuver.
The aspect ratio system is derivated from the horizontal stadimeter present in early war uboats and interwar periscope makers, which was not unknown to the americans. It was a useful gadget in the peacetime maneuvers, where dimensions of target ships were well known, and it helped the commanders develop the seaman eye. But in wartime, for all circunstances explained by RR, it was mostly useless.
Not so much the fixed wire, which was still used, but again not as widely as plain eye estimate.
The reason I adapted them to a quick tutorial for us submarines was to get people started on manual targetting and familiarize them with some concepts. Since the AR and FW methods were useful in situations where target dimensions are know and there is no pressure on the shooter, they fitted well the concept of SH3/4 gaming. We don't risk our necks, and the limited number of ships in the game allows us to use it. And, in the same run, the player starts understanding concepts such as the non-linear change of AOB, and the sense of relative motion of the target. In my experience, after some time using the system, the user discovers that he has developed enough experience to tell the AOB by naked eye estimation, even in a 2D environment as a game screen. And the speed also starts being judged with some accurancy, at least in some 3-4 knots interval.
I don't however concur so much with the idea that it is impossibel to guesstimate more or less correctly a ship's length (Mast heigth is more difficult), because with some practice it isn't so difficult. There are certain naval construction rules that help a bit, because shipbuilders always tend to keep some proportions, and because a few meters up or down in length don't make a lot of difference for us.