ZIGZAG

Vantskruv · 05-31-20, 11:40 AM

Thanks @derstosstrupp.
And thanks @Pisces for your thorough answer!

I have made some measurements, and indeed the little differences between the approximated bearing 4 and real bearing 4, makes it really hard to get the correct position of the convoy (in my example one degree of measured difference would change the targets course by about 10 degrees, and reduce their distance from ownship to the half!).

Though, I have been thinking about changing the course after measuring the bearing 3, as you told! But I ignored it as I thought changing the speed would be enough, and being afraid that calculations/measurements would have more errors because it is harder to approximate your position after a course and speed change, as I did the measurements on 30m depth without surfacing (playing safe).

I will reconsider, and try to implement course changes, and see if that, even though ownship position maybe a little more off, I may get a more precise result than only changing speed (hence, it is better to strive for the bigger difference between approximate bearing 4 and real bearing 4, while sacrificing approximation of ownship position?). I just need to figure out the turn radius of different speeds of the ship, both submerged and surfaced, and also if the speed will change while turning. Maybe it is not too hard to approximate/calculate your position after a turn after all, and that would beneficial.

Also, a theory of mine, I guess the 4-bearing method is more used at longer ranges, and I guess you may get better results if at long range, than close range. I am not sure what I am basing that of, it is just a hunch.

05-31-20, 11:40 AM	#5
Vantskruv Swabbie Join Date: Jun 2012 Posts: 7 Downloads: 9 Uploads: 0	Thanks @derstosstrupp. And thanks @Pisces for your thorough answer! I have made some measurements, and indeed the little differences between the approximated bearing 4 and real bearing 4, makes it really hard to get the correct position of the convoy (in my example one degree of measured difference would change the targets course by about 10 degrees, and reduce their distance from ownship to the half!). Though, I have been thinking about changing the course after measuring the bearing 3, as you told! But I ignored it as I thought changing the speed would be enough, and being afraid that calculations/measurements would have more errors because it is harder to approximate your position after a course and speed change, as I did the measurements on 30m depth without surfacing (playing safe). I will reconsider, and try to implement course changes, and see if that, even though ownship position maybe a little more off, I may get a more precise result than only changing speed (hence, it is better to strive for the bigger difference between approximate bearing 4 and real bearing 4, while sacrificing approximation of ownship position?). I just need to figure out the turn radius of different speeds of the ship, both submerged and surfaced, and also if the speed will change while turning. Maybe it is not too hard to approximate/calculate your position after a turn after all, and that would beneficial. Also, a theory of mine, I guess the 4-bearing method is more used at longer ranges, and I guess you may get better results if at long range, than close range. I am not sure what I am basing that of, it is just a hunch. Last edited by Vantskruv; 05-31-20 at 11:50 AM.