The new and improved four bearings method

[Kuikueg]

I have completely rewritten my tutorial on finding position, speed and course of a target given four bearings to it, to include significant improvements in the procedures in terms of simplicity, some variations of the problem and, I hope, clearer explanations. This new version owes a lot to the kind comments and insight from many of you and I thank you all for it, specially Makman94.

You can find the tutorial here:
http://lnpi.net/docs/the_four_bearings_method_v2.pdf

[makman94]

you know Kuikueg, when i first saw your thread with the first version of ''Four Bearings Method'' ...i thought that the ''Four Bearings Method'' is one of the best (if ...not the BEST) thread that i have seen at Subsim the two years that i am here. Threads like this is the real power of Subsim

your method is really just a piece of art ...even the manuevering boards method demands some constant speeds(for our boat) and two sets of three bearings to have the results but yours...is just excellent,,,we have nothing to keep constant (only time intervals must be equals or analog) ..we can change speed and course anytime we want and repeat until we get to good positions...we are just absolutely free and this makes this method just...the best i have seen ! with four bearings ONLY ...we have true course ,range to target and speed of target ... what can i say?if you know a simplier method on manuevering board than Kuikueg's...please guys ...share it !

and now you are 'coming back' with this...version 2 !even simplier(i will say...a lot simplier !!)..is making this method even flexible than ever !your new discoveries for finding the 'red line' are making it a piece of cake on map drawings !
i am ...SPEECHLESS Kuikueg! the beauty of your thought is just amazes me !(you did it ones and you are doing it again!) .if i ever have voted for best threads...would,definetely, be yours !
my opinion is that you must be award not only by Subsim but from REAL NAVIES too(i am not joking) !i believe that this method(if we assume that doesn't exist allready) , surely ,deserves the best place in navies manuals for the situation: Chasing a target that is moving with a constant speed at a constant course (REALLY...i am wondering...are there such targets in real life?i mean targets that are moving at constant speed and course...)

Having said all these ...i only want to congratulate and say thank you for sharing this piece of art with us Kuikueg !


ps1: i had totally forgoten 'our' theme Kuikueg ! i promise to look at it and send you my thoughts !

ps2: to moderators : seriously,if there is a thread that must be sticked ...this is it ! it is just an ...'advertisment' for the high level of Subsim !

[Walle]

This is a very effective method! I tried it out yesterday, and it all worked out like a charm! Thank you for taking the time to share this!

Ps: And I concur, this thread should definitely be a sticky!

[irish1958]

Can somebody upload it to Subsim? Filefront doesn't appear to be working.

[Walle]

I could do it, but I'm sure Kuikueg would rather do it himself (so I don't get confused as the author).

[Harmsway!]

I concur. I only ran across the original method about a month ago. I was in the process of teaching my son geometry when I came across this. It fit right in what we were learning on the Theorems of congruent segments and congruent triangles.

Funny things is I spent 40 minutes watching someones video on this and was confused as heck. Luky I found your well written pdf and it all became clear as mud.

Thanks

Yes every skipper needs this in there hands.

[Kuikueg]

Originally Posted by makman94

...even the manuevering boards method demands some constant speeds(for our boat) and two sets of three bearings to have the results but yours...

Thanks for your comments, Makman. It's not such a big deal.

You are right about the maneouvrig board: the fact that you or your target become the center of coordinates limits somehow your maneouvres. Frequent changes of speed or course during the proccess at the very least will clutter the board so much as to make computation complex, ackward and confusing. But we have to acknowlege the need for it. In real life your own position is uncertain -without GPS, that is- and becoming the origin of coordinates simplifies the problem for that reason. Also, the scale of a real chart can be a limit to a direct method. The triangle might fall outside the chart, or be as little as to make accurate protracting of its distances imposible. There are very good reasons why navies use the maneovring board.

In the manual from the USN for the use of the MB, back in the forties, there is a case estated "given six bearings to contact establish its course, range and speed" or something like that. I have not gone through the proccess it describes, but I suspect that the doctrine for using six bearings instead of four, which would be enough, comes from the need to compensate for the uncertainty of your own position.

I would like to see a MB implemented in SH5. It really is simple, as much as including a nomograph, which is already done. We could use the real procedures manual in that case.

[makman94]

Originally Posted by Kuikueg

.... There are very good reasons why navies use the maneovring board...

i have no doupt that there are very good reasons for navies using the manuevering board . in fact , i am sure that there are very good reasons .
i was talking for methods to use in our game ...comparing yours with mb's one.
for real maps ...yes,maybe triangle will become too small or too big, but if i was a navigator officer ,certainly, wouldn't ignore ''The Four Bearings Method'' (in case that triangle and drawings were 'in' my map)

Originally Posted by Kuikueg

... I have not gone through the proccess it describes, but I suspect that the doctrine for using six bearings instead of four, which would be enough, comes from the need to compensate for the uncertainty of your own position.

i have to 'dig' to find the manual for mb that describes the situation (find course-speed-range to target with bearings only) and i will sent it to you to have a look at it . you will see that it needs six bearings(with constant speeds and courses) for collecting only the target's data . it has nothing to do with the uncertainty of our own position.

[Pisces]

Originally Posted by makman94

...
i have to 'dig' to find the manual for mb that describes the situation (find course-speed-range to target with bearings only) and i will sent it to you to have a look at it . you will see that it needs six bearings(with constant speeds and courses) for collecting only the target's data . it has nothing to do with the uncertainty of our own position.

This is probably the part you mean. It's a 2 page excerpt of the MB manual:

http://www.filefront.com/13598315/bearingsonly_TMA.pdf

[makman94]

Originally Posted by Pisces

This is probably the part you mean. It's a 2 page excerpt of the MB manual:

http://www.filefront.com/13598315/bearingsonly_TMA.pdf

yes Pisces, thats it ! the original pages of manual containes another same example with it (but with different bearings ,speed and courses) .but it is the same example with this.

[musides]

Excellent work and great descriptions!

[MCM]

Is there a new download link for the improved fast method? THX!

[pythos]

Doing the four bearing method, and having no luck.
The point of failure seems to be at the point when the parallels are moved to intersect Bearing 2.
Having had numerous failures in acquiring contact course I decided to try this with map contacts on and was using the TDC historical mission (one ship on a east to west coast, and the U- boat on a northerly heading.)
I used the periscope for the bearing info, and found that when I drew out the parallels on bearing 1 and 3, that the course was nearly perpendicular to the actual contact course.
Then I looked at how to acquire a predicted course line that would match the contacts East to West course, and honestly I could find none.
I have done the tutorial included in Steel Wolves for the four bearings several times, and encountered that although the tutorial is saying "we have acquired a bearing of (place bearing here), that when I clicked on the sonar operator I get "no sound contact".
In actual practice I find the sonar bearings useless (even when tracking a single contact, as the operator only reports the closest contact, and in a shipping lane that can be many instances of the closest changing during the course of acquiring four bearings over 20 minutes.
I sure wish I could get this method to work, cause if this works this will make this sim really immersive.

[DieReeperbahn]

I've had mixed results as well. I find that you must use the highest magnification when making a plot or too much error will creep into the solution. But I just play on and assume the target changed course or speed or my WO is tired...