Judging AOB by eye - tutorial

[joegrundman]

Judging AOB by eye tutorial - single ships

It requires two things
a) practice (which on the whole we are not short of)
b) knowing what to look for.

To be sure, there are times when it is hard to judge by eye – at extreme range it is hard, and in the dark at medium range it is hard, and there is a band of AOBs between 20 and 50 that are harder than the others.

This is an extract on the subject from the invaluable USN submarine torpedo fire control manual (1950)

http://www.hnsa.org/doc/attack/index.htm

Section 803

(b) Estimation of angle on the bow by observation through a periscope is one of the arts peculiar to submarining. An officer's ability to accurately estimate angles on the bow increases directly with his experience in submarines.

It’s not necessarily easy, but once you have the skill it’s by far the fastest way to obtain AOB. If you also have a tool that can rapidly convert AOB to target course for you, such as the Submarine Attack Course Finder (or ISWAS – do a search to find threads on the subject), or the German Attack Disk, or Angriffscheibe, as found in the U-jagd tools mod or the OLC GUI for SH3, then the whole process of visuals to target course, to submarine attack course takes seconds.

I have used SH3 for these shots, but of course it makes no difference what game it is, or even if you are judging AOB in the real world (if you haven’t mentally planned a firing solution at a passing ship while standing on the beach, you are a lightweight!)

There are four things you are looking for, apparent length, the orientation of the masts, the position of the bow wave and the front of the bridge

Apparent length

First is apparent length. It is important to note that the apparent length of the target changes with the sine of the AOB.

This means that from AOB’s 90-60, the apparent length of the target doesn’t change much. This means it can be difficult exactly distinguish between AOBs of this range, but on the plus side it means that a variation in this range has a minimal effect on your torpedo solution.

Then the apparent length changes rapidly between 60 and 15, and then it changes slowly again.

The apparent length at 30 degrees is exactly half the apparent length at 90 degrees. In general this is a big source of confusion before you are acclimatized to visual AOB spotting, as one instinctively tends to see this stage as 45 degrees.

Masts and bow wave

For small AOB's you look at the position of the masts in relation to the funnel. this will help you to distinguish between AOBs of 0,5,10 and 15. The point at which the bow of the ship cuts the visible bow wave is also very useful.

Bridge

At larger AOB's you look at the part of the front of the bridge that you can see. The more of this you can see, the further from an AOB of 90 it is.

AOB 0

This is one of the easiest to recognise, since the view of the ship is symmetrical



in fact you can see that it is not quite symmetrical, there is an AOB of about 1 degree.

If you are really struggling to get an AOB, then one approach is to cut the T of the target ship, and once you see this view, you know the target is on a reciprocal course, then continue and adjust to make the sternshot.

E.g. let's say i am on a heading of 10 degrees, and when i have this view the bearing to target is 220, then true bearing to target is 10+230 = 230. Reciprocal of 230 is 230-180=050. Target course is 050 degrees.

this is particularly useful if you are making a convoy attack from inside the convoy, as you will generally have passed directly in front of one ship or another on your way into position.

AOB 5

Now the bow is not in the center of the apparent bow wave, it is about 3/4 of the way across, and on a longish ship the front masts have moved across a small amount relative to the funnel



AOB 10

At AOB 10, the bow is now almost all the way across to one side, only about 1/7 of the other side of the target is visible around the bow. Also the front masts ahve now "cleared" the funnel.




AOB 15

At AOB 15, it is just no longer possible to see any of the other side of the ship, and all the masts appear to have just become on one side of the funnel or the other.



AOB 20

This is one of the more difficult to identify. The bow wave no longer clearly helps and the masts and bridge are not too helpful either.

Apparent length is not yet half the expected full length. Certainly this is one of the easiest AOBs to overestimate. If it's possible, note that you can still just make out the anchor on the other side




AOB 25

Now the big difference with 25 from 20 is that some of the cranes on the ship appear to meet in the center, and that some of the aft cranes are no longer obscured by any of the bridge, but also note that the ship has lengthened greatly since the AOB 20



To be continued...

[SmokinTep]

Good stuff....thanks.

[joegrundman]

AOB 30

At this AOB, the apparent length of the ship is half the actual length. In addition if you now look at the side of the bridge section, you will see in this ship, the corner is about 1/5 to 1/4 the way across, and in a ship with doubled masts, like this one, a small gap has appeared between the different sets of masts



AOB 35

Nevermind that the picture is smaller! The corner of the bridge is now about 1/4 the way across, and the gap between the mast sets has grown



AOB 40

A ship with masts of this kind now shows an even spacing between all the masts at the AOB, and the corner of the bridge is in line with the funnel (clearly this is not a useful marker with split freighters)

you can however say it is approaching 1/3 the way across




AOB 45

Now i'm getting a bit bored of writing comments! For sure this mid range is the most difficult. The gap between the mast sets has become wider than the gaps between the masts, and the corner of the bridge is now under the funnel. the apparent length of the ship is now 7/10 of its actual length.



AOB 50

Now it starts becoming a bit easier again. At 50, you are beginning to see the full length of the ship (actually 3/4 still), and the gap between the mast sets is clearly seen



AOB 55




AOB 60

At this AOB, the corner of the bridge is about half way across the visible bridge



AOB 65



AOB 70

We are now definately seeing more of the side of the bridge than the front, and we are beginning to see the masts "side on"



AOB 75



AOB 80



AOB 85

This is now only very slightly off being exactly perpendicular

[predavolk]

Wow, nice! I ID AOB visually, so these are some handy tips indeed!

[klh]

Well done Joegrundman. I find that I almost always overestimate the AOB with my Mark I eyeball. This will help tremendously!

Have you considered putting this into a pdf? This is something I would love to laminate and keep handy.

[ktrboston]

Great job Joegrundman! this is a help full post. I also use the Submarine Course finder it is an invaluable tool. I always use because it has so many uses. It is a must have for all Captains.

[brett25]

hey guys,

heres a .pdf version of that torpedo manual:

http://files.filefront.com/Torpedo+A.../fileinfo.html

Also the submarine commanders handbook .pdf

http://files.filefront.com/The+Subma.../fileinfo.html

[CptGrayWolf]

Originally Posted by brett25

hey guys,

heres a .pdf version of that torpedo manual:

http://files.filefront.com/Torpedo+A.../fileinfo.html

Also the submarine commanders handbook .pdf

http://files.filefront.com/The+Subma.../fileinfo.html

brett25, thanks for the submarine commanders handbook!

[brett25]

joegrundman, tomcattwo

I hope you dont mind, but I made a .PDF version of your excellent tutorial to help me study it better. I will post it here for others unless you have any objections

http://files.filefront.com/AOBpdf/;9.../fileinfo.html

[Sailor Steve]

Those are cool, Brett! Thanks!

[Tomcattwo]

Brett,
No problem from me. The more the merrier
R/
TC2

[CptGrayWolf]

Don't let the enemy know about this. They'll start changing their masts around and screw us up!

[joegrundman]

Originally Posted by brett25

joegrundman, tomcattwo

I hope you dont mind, but I made a .PDF version of your excellent tutorial to help me study it better. I will post it here for others unless you have any objections

http://files.filefront.com/AOBpdf/;9928600;/fileinfo.html

sure i don't mind. Sounds like a good idea

[Tupolev]

I apologize for grave digging this thread. ..

Does anyone have the PDF file of this AOB tutorial? I've been googling my fingers off with no luck.

Thanks!

T

[Sailor Steve]

Funny you should ask...
http://www.subsim.com/radioroom/down...o=file&id=3467