Submarine Attack Course Finder (a.k.a. Is-Was / Banjo)

[Von Hinten]

Looks great! Thanks for making and explaining it.

[OakGroove]

Very nice! Thanks for sharing.

[jmr]

Originally Posted by Meridian

Looking forward to printing and making one of these up, nice job.

I assume Parts "P" & "C" are printed on transparent media?

I think it's just the periscope one that needs to be transparent but it would be nice if someone else can confirm this.

[Hitman]

I only made the scope transparent, the other one can also be made transparent -and in the original it seems to be- but doesn't make any difference at all

[sqk7744]

Very neat! ~ would someone be so kind as to post another step by step example.

Thanks much!

I've got these wheels down (I think):

-A (relative bearing)

-B (true course / compass heading)

-Periscope Transparency ( if the Periscope marked end with view window goes on the Subs bearing to target) then the 180 (reciprocal) arrow points to AOB right?

[now for the wheel that came off the bus...]

-D The AOB wheel is where I'm getting confused ( I'm pretty good at judging AOB manually into the TDC, but want to use the Neat Wheel.

[sqk7744]

thanks much

[Captain Krunch]

First off, I'm glad to see interest in the Is-Was I made; I hope it helps people enjoy SH 4 even more.

Regarding transparency, the original had both the C and Periscope dials clear, but after your comments, I don't see why the C dial couldn't be printed on paper. But the Periscope dial must be clear so that you can see the values underneath.

The way I believe the wheel works is like this. Prior to a ship sighting, the A and B dials can be pre-set together to your heading, with the "0" degrees mark of the A dial representing the front of the ship, and the B dial showing true heading of the ship, by placing the heading value at the A dial "0" degrees mark. So if you're heading due east (90 degrees), then the A dial "0" degrees mark = the B dial "90" degrees mark.

So let's say you're traveling due east, 90 degrees. Then suddenly, you get a ship contact (Via sonar, periscope, etc. It doesn't matter). "Sir, new contact, 300 degrees relative!" What I do is I move the Periscope dial so that the triangle is over the A dial "300" degree mark. This is also equal to a B dial value of "30" degrees. The B dial can now tell you what true heading to take if you want to head straight for the contact. "Helm, make new course 30 degrees".

But let's pretend you don't change course. Ok, now the last bit of the puzzle is Angle on the Bow. You have two ways to use this. First, if you can determine the true course of the contact via plotting, you can input the contact's heading to determine AoB. "Sir, contact heading is plotted out to be 330 degrees!" You do not move the A, B, and Periscope dials; you move the C dial until the "0" degrees mark of the C dial is pointing to the "300" degrees mark of the B dial. When you do this, you look at the Periscope dial marker 180 degrees opposite the Periscope triangle. This marker points at "120", on the left side of the C dial ship, so this tells you that the contact AoB is 120 degrees port.

On the other hand, let's say you visually estimate the AoB, and decide it to be 100 degrees port. You move the C dial "100" port value so that it matches up with the Periscope dial marker that is 180 degrees opposite the triangle. When this is done, you can then determine via the B dial that the contact's heading is 310 degrees true.

Once this is done, you decide to make a direction change, and head straight for him. You do not move the B, C, or Periscope dial; instead, you just move the A dial so that the "0" value matches up with the Periscope marker that you had already preset above.

That's probably a way-too-verbose answer, but I hope it helps. I suggest playing around with it for a while, and eventually you'll get the hang of it. Good luck!

[WernerSobe]

im not sure if i get it right...

You can find the course of your target with that? Why anyway? the more interestning thing to find out would be the AOB.

[WernerSobe]

btw ive seen pictures of a wiz wheel as it was used in german submarines. They have used the known or guessed length of the target to find its AOB. Basicly its the same method as you find the range by mast high.

[panthercules]

Originally Posted by WernerSobe

btw ive seen pictures of a wiz wheel as it was used in german submarines. They have used the known or guessed length of the target to find its AOB. Basicly its the same method as you find the range by mast high.

Hmmm - now this sounded like a very cool (and relatively easy) idea at first - if you have a decent range estimate, and you can measure the observed/apparent length (presumably by reference to the markings along the horizontal/x-axis of the scope/TBT), it would seem to be a relatively simple matter of math/formulas to compute the AOB based on the relationship of the apparent length to the actual length (available from the recognition manual). However, I wonder if a wiz-wheel to do this would really be any easier to deal with than the Is-Was thing described in this thread, and this one seems to let you calculate either AOB or target course, depending on which data you already know, which is probably more useful than the above sort of special-purpose AOB calculator would be. Will have to see if I can put one of these Is-Was things together - sounds very cool.

[sqk7744]

Thanks CC!

That did the trick!

Cheers

[Hitman]

Hmmm - now this sounded like a very cool (and relatively easy) idea at first - if you have a decent range estimate, and you can measure the observed/apparent length (presumably by reference to the markings along the horizontal/x-axis of the scope/TBT), it would seem to be a relatively simple matter of math/formulas to compute the AOB based on the relationship of the apparent length to the actual length (available from the recognition manual).

I'm finishing a tutorial with screenshots on a method to get the AOB based exactly on that. I call it the "Aspect Ratio" method, because it relays basically in how much the relationship between height and length of the ship you see changes towards the standard aspect ratio when at 90º AOB.

This is the part that dials with the AOB:

2.- AOB (ASPECT RATIO METHOD)

Each ship has its own "Aspect ratio", which means the difference of its length versus its heigth. For example, a 100 yards long ship with a mast of 33 yards has an aspect ratio of 3,33:1. Now, because what you can see of the ship’s height remains constantly proportional (The mast) at any given distance, while the length you can see will change also proportionally depending on the AOB, you can read from your scope or TBT the new Aspect Ratio the ship shows you, and by comparing it with the standard aspect ratio at 90º, get the AOB directly.


You just have to do this:


1.- Note the target’s Standard Aspect Ratio (F.e. 3.95 in a Medium Modern Composite). You can get it from the recognition manual (length 103.6 metres divided by a heigth of 26.2 metres in our Medium Modern Composite) and have it listed already for faster consulting.


2.- Pause the game (You are now a Tracking Party member), and count the scope marks until the top of her mast, and the marks from her bow to her stern (Hint: The scope locks at the exact centre, so just count from the centre to the bow fairwater and multiply by two). It is easier to do if you raise the reticle to align the horizontal division with the mast top, like the next image shows.



Divide the number of lentgh marks by the number of heigth marks, directly (No need to convert them to anything else). In our example, we see aprox 13.25 marks to the bow (26.5 marks total length of the ship) and almost exact 7 marks to mast top. Dividing it, the resulting value is 3,78


3.- Use following formula to determine the percentual variation of the aspect ratio:


New Aspect Ratio (3,78 in this case) x 100
Variation = _____________________________________

Old Aspect Ratio (3,95 in this case)


Variation in this case would be 95,8 %, i.e. nearly 96%


4.- Use this ruler (It is simply a Sinus scale) to determine the AOB:



In this case, 96% in the lower scale represents a 75º AOB, as you can see in the upper scale. Easy, isn’t it?

Now unstop the game, plug that value in your tool and send it to the TDC.

NOTE: If the target is heading away from you (No converging course) the result in degrees must be added to 90º. The aspect ratio variation will be the same if the target has an angle on the bow of 45º or of 135º, i.e. you will see 70% change towards the original Standard Aspect Ratio in both cases, so it is up to you to correct that. But its is fairly easy to see in general terms if the target is moving away or converging, and the masts of the ship will always provide you an orientation in the most difficult cases.

[don1reed]

Excellence awards to :

Capt K for iswas & Hitman for aspect ratio. Nicely done gentlemen.

[WernerSobe]

well actualy the real AOB finder that ive seen pics of only needed the known length and "angle of projection" data. Seemed to be very easy and quickly to set up.

angle of projection is the ralative angle of the ship to your boat from bow to stern. You can find it by counting the horizontal marks in your persiscope. The manual says each mark is 1° or 4° depending on zoomscale.

[panthercules]

Originally Posted by WernerSobe

well actualy the real AOB finder that ive seen pics of only needed the known length and "angle of projection" data. Seemed to be very easy and quickly to set up.

angle of projection is the ralative angle of the ship to your boat from bow to stern. You can find it by counting the horizontal marks in your persiscope. The manual says each mark is 1° or 4° depending on zoomscale.

Well, I assume that you would still need to know something else besides the known length and apparent length ("angle of projection") - i.e., the range, because the apparent length will obviously be different at different ranges. I was thinking about a method that used the range directly, along with actual and apparent length, but that of course requires you to first determine the range and then input it into some formula/chart/wheel mechanism for solving AOB. The aspect ratio approach outlined above takes the range into account indirectly - since the apparent mast height also changes with range like the apparent length, by using the ratios of the two you don't need to actually determine or know the range to solve for AOB - you only need the apparent height and apparent length (to compare against the known values from the recognition manual or pre-determined aspect ratios from a chart), and both of those can be obtained from the 'scope - a clever way to avoid the stadimeter CTD bug for those who still have that

I'm not sure if I'll take the time to use these methods during combat, but they sound like a pretty good way to confirm my AOB estimates and "train" my eye during sub school practice to make better guesses using the Mark 1 Eyeball.