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Old 08-05-2020, 01:30 PM   #3
Pisces
Silent Hunter
 
Join Date: Dec 2004
Location: AN9771
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Unfortunately the screenhots you showed get reduced in size, so it is very hard to see it. Jpeg compression doesn't make it better either. (there are site to which you can upload the images for a limited time and it shows them in better quality. like imageur.com, postimage.org, imgbb.com)

But if you look at the map image then you'll see that they, all three of them, are showing about the same AOB: around 135 left/port. With a bit of effort because of the image-quality I notice that I can look into the backside of the front structure, and not to the front of the back structure.

(On second thought, my draughtsman eye suggests it is closer to AOB 120 left.)

Can this be refined or narrowed down or proved? With more experience for certain. But as a rough first guess you can take it as it is. You see it has 2 sets of kingpost masts. Meaning 2 times side-by-side masts. If you set the bearing tracking selector to this (attack) periscope, then set the AOB to 135 left. Turn the attack periscope about 45 degrees left to get the AOB needle to point down to 180. Then notice the angle at the bottom. Turn to that course to go parallel. (Or what we think is parallel) When you are surfaced and moving faster than it then you will see those masts converge. And when they do you know the AOB if 90 degrees. And you can refine the AOB setting in the TDC for more accuracy. After that you can try to look at the ships from different positions (as you move around it) and see how those relate to the TDC AOB dial at that moment. That helps you learn to distinguish AOB better.

It also helps to compare its shape with the recognition manual. In your imagination try to match the size of the recognition manual side-on view to the actual view. And see how much it looks shorted. 25% the side-on length indicates an AOB of 15 (or 165) degrees. Halve the size of side-on indicates AOB of 30 (or 150). 70% of side on indicates (45 or 135) degrees. 90% indicates 65 (or 115) degrees. The above does suggest there is a mathematical relationship between the length and height ratios of observed versus true size. It's by the law of sines. But it will go quicker if you learn to do this by eye rather than spend minutes measuring and calculating it.

Last edited by Pisces; 08-05-2020 at 02:00 PM.
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