target speed: the eighty-ten method

[greyrider]

if you have been reading this post, you know that a good speed estimation can be obtained by using the angular arrangment of 80-10, miles before you even see the target.
we can also get a fix on the targets course, and know pretty much what course the target is on as well. theres only one problem tho, because we wont know the range of the target,
we might know the course its on, but we wont know just where it begins, how far away it is, unless we are able to estimate range with the hydrophones, and that im going to try to show you is possible.
after listening to the sonar training records of the naval historical society, i have identified at least 2 ways sonarmen estimated target range by passive sonar.
one is by the loudness of the targets propellers, and the other way by the width of the targets sound signal, which i will show in another thread at some point.
but getting back to target course, once you have set up the 80-10 arrangment between target and submarine, if you worked with the AOB trainer, there was an explanation with it that described
how to determine target course, from either a visual contact, or sound contact.
to determine target course in the 80-10, you must remember that the target course is relative to the submarine. so using the original example, in the 80-10,
we have a target bearing 280, relative to submarine, since the targets bearing is 280, its more than 180 degrees, so you subtract 180 degrees from 280, and you
have a general direction now of the targets course. but we havent factored in the aob yet. so lets figure that in as well, so we can have a somwhat accurate target course line.
the target has a starboard aob, and since its a starboard aob, we have to subtract the aob, after subtracting 180 from the 280 target bearing, if the target is
being held constant at 280, it has a 10 degree aob, so we subtract 10 degrees from 100 degrees, and the result is the targets course relative to the submarine, 100 - 10 = 90 .
so the target has a 90 degree course relative to submarine, the only problem tho is what i stated at the begining of the post. it really doesnt matter tho, because if you keep the 80-10 arrangment, and continue to close the target,
your going to see it anyway, but i just wanted to show you that.
even if the aob is not ten degrees, you can still get target course, just like speed because you only have only a few courses that the target can be on, in the 80-10.

joe, i have download your info, i will check it out later, thanks

one thing joe, im a lazy captain, i dont wanna plot, i love it and hate it all at the same time, and becuse im lazy, i just want to drive the submarine to the target, shoot it, and then go away.