Determining course of contact that is "smoke on the horizon"

[vdr1981]

Great explanation Jaystew .
However, it's pity because most of the players will be more interested in how to enable arcade minimap and/or GPS/map contacts updates rather then actually learn about some real life WWII procedures used by submarine captains...

[pythos]

Yea, I actually dislike feeling the need to turn map contacts on. I think I am going to turn on ONLY the hydrophone ones as there is no "report closest merchant" opposed to "nearest contact" or "nearest warship" as if there is a warship around "nearest contact" will report the warship over a merchant.
I WANT to go to real navigation and mostly no contacts, once I understand what I am doing. LOL

[Jaystew]

I have hosted the large image file on imgur. Its free and they allow you to do unlimited upload of png/jpeg files. You can sort them into albums. Etc. I think it is a very good free service. I use it to host my maps as well and also the above tutorial.

Here is the tutorial with a sort of slide show please check it out and give me some feedback.
http://imgur.com/a/EstMH#0

Also my maps so far I've completed 5 of them, they are huge, feel free to download the full resolution.
http://imgur.com/a/ssMsk#0

Also a link to that thread. http://www.subsim.com/radioroom/showthread.php?t=213138

[Jaystew]

I think for me when I'm on the open ocean I don't bother checking the hydrophone as often as I should. But in the early war it is definitely worth checking when going through a 75-50km chokepoint rather than doing a visual sweep because you can cover so much greater area. I also dont think its a bad idea to do it every 2-4 hours while on patrol or in a high risk area.

Knowing that there is a contact to the south when it could only likely be an escort patrol such as in the shallow waters or near a port, definitely helps make good navigation decisions and avoid the enemy. Once in visual range its sometimes hard to get out of a slow sticky situation with escorts. Especially in shallow shallow shallow water!

As the war goes on it becomes more and more important as surface travel is either limited, dangerous or almost impossible. More destroyers and aircraft in 1940 make for minor irritants to surface travel, in 1941 especially after the USA enters the war it becomes even more limited. In 1942 I think its dangerous to be on the surface not just during during the midday but even at night. In 1943 with all the aircraft if you get spotted or detected by their radar they will relay your position and if you are not in deep water the destroyers will ASDIC you to death and DC you and use hedge hogs boom boom boom. Not only in 42/43 do you not have the advantage but even with the schnorkel until the Type XXI in late 44/45 does the Kriegsmarine have the advantage again and at that point the war is already lost.

[Jaystew]

Originally Posted by vdr1981

Great explanation Jaystew .
However, it's pity because most of the players will be more interested in how to enable arcade minimap and/or GPS/map contacts updates rather then actually learn about some real life WWII procedures used by submarine captains...

I think the trig throws people off because you can use trig on the fly to help with angles and shooting solutions. But a lot of the intercept data is geometry rather than trigonometry. I was much better that geometry than trig and so I stick to what I know from geomergy. Algebra easier than calculus etc.

I know that A^2 + B^2 = C^2 in a right triangle from geometry. Now that works for right triangles, those with a 90deg angle, which just so happens to be exactly the angle you want to attack your torpedos with on the hull of a target. So I say screw trig. I dont have time to do trig in the boat while lining up the ship, and keeping the boat in order, checking out asses for destroyers making sure there are no AC etc.

Even the best captains under that level of stress and daily grind, do you think any of them would want to put their trust in complex mathematics when the KISS keep it simple stupid principal applies?

Bologne, they want to sink the the ship and go home. Just think one complex calculation with a single error could throw off the torpedos. Why use complicated stuff when you could use easier stuff. Of course if they had access to GPS they'd probably use it too but bah they didn't so why would we in a "simulation" LOL turn on GPS cheating. Come on guys. What kind of Skipper are you, are you on a 3 hour tour with Gilligan?

Simple geometry easier faster to calculate some in your head even.

A+B=C My favorite right triangle is 3^2+4^2=5^2
9 + 16 = 25

[DieReeperbahn]

Originally Posted by Jaystew

A+B=C My favorite right triangle is 3^2+4^2=5^2
9 + 16 = 25

I always liked
A^3+B^3=C^3

[pythos]

Well I was finally able to try this. I discovered to my chagrin that the line of bearings I made did not intersect at all. Instead they fanned out. This gave no useful data at all other than the contact was moving. I then turned contacts back on, and tried this again, and saw that the termination point of the lines of bearing did kinda follow the course of the contact, but were many km off. Still need help here.

[Jaystew]

Can you show or tell us list us your observations...

Sometimes the lines of bearing do fan rather than converge but this indicates the target is move faster thank you or the course you are using against their course is too wide or even perpendicular to their own.

Lets debug it.

[Jaystew]

Originally Posted by DieReeperbahn

I always liked
A^3+B^3=C^3

I dont get it. Where does this calculation help you in submarining?

[pythos]

It was a destroyer, and what you said is what I was thinking, the contact was going fast. So does that mean this method won't work on fast moving contacts? I got the initial report, set my heading toward the contact (smoke on the horizon), set my speed to 10 kts, marked my point, and drew a 30km line. Waited 2 minutes, and placed the next mark, I forget the bearings given. As I stated though, the lines fanned out, and the terminiation point of the lines if a line was drawn from point to point would almost parallel the course of the contact. (recall I did have map contacts on).
Hope this helps.

[Jaystew]

Im having trouble visualizing what you were observing. There are times when triangulating is going to be difficult or impossible. If the contact is moving away at high speed. A good thing for a destroyer, you would typically see a converging of those line of bearing farther and farther away.

For example if you drew a circle every time around the location where your last 3 lines of bearings get closest to each other and then each time you did that those circles would move gradually would be farther and farther away even though you should observe the lines of bearing being closer and closer together.

If they are starting to fan out and the tighten up that would to me indicate a destroyer running perpendicular. One running parallel to your own subs course. Would be relatively easy to spot so long as you are both heading in the same direction, if you are heading in opposite directions the angles between the lines of bearing will get smaller and smaller.

Maybe we are making this too complicated. If you have a visual contact to make the general direction of travel as simple as possible observe the smoke from the ship. Think of the ship as a candle, as you move a candle from left to right the smoke is highest in the left where it originated from and lowest at the point closes to the flame. If that smoke is on a steady rise without a trail either on the left side or the right side, that ship is either coming towards you or heading away or stationary. If it is larger in 2 minutes its coming at you. Let me make a few more diagrams to aid you and then we'll see if we can figure out how to determine the course of a fast moving target.

If its pressing at 30 kts or so you may not be able to exactly nail down its course without trig but with practice you should be able to guess it within 10-20 degrees based on the sight picture of the angle on the bow and your ship's current heading. Meaning if you are heading North and you see a car traveling from left to right which direction is it heading? It is heading East. Now suppose you are parked at 330 and when looking at the AOB or angle on bow it appears to be at 60 degrees of the right side, so you can fully see the bow and not see the stern, so take a guess at which angle you are seeing. If you are at 330 and the contact is heading left to right and you appear to be at AOB 60 Right then it must be heading about 030. It is a lot of guessing and you wont always be right. Which is why you make more than one observation.

The closer you get the easier it is to make accurate guesses, and shorter the torpedo run has to be. As long as you are in deep water there is no benefit to attacking beyond 900-1000 meters and if you can get inside between 400-800 meters. Do it.

One torpedo shot from the hip at that range at high speed almost always hits with enough time to launch a 2nd one on a modified gyro angle if the first one fails to detonate.

[finchOU]

Originally Posted by Jaystew

If that smoke is on a steady rise without a trail either on the left side or the right side, that ship is either coming towards you or heading away or stationary.

Maybe a different example? Smoke in SH5 is effected by the current wind condtitions, therefore Smoke is an indication of wind direction and intensity but not ship course.

[DieReeperbahn]

Originally Posted by Jaystew

I dont get it. Where does this calculation help you in submarining?

I'm joking It's Fermat's theorem...no solution.