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Originally Posted by flag4
whish i could understand the information in the link...it sounds so cool !!
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Yeah, re-reading it I don't find myself to be very clear either. But I don't know how to explain it better. Well, I'll try anyway.
If you and the target are moving head-to-head you are closing with him at pretty quickly, right? Both speeds are added in a head on collision. If you are both going the same direction you are either closing or extending away much slower. The difference of the 2 speeds. Now, the time interval that I calculated is the longest time it takes the target to go from one side of your hydrophone detection area to the other side of it, while you are moving. And assuming he comes very close or just outside of visual range. This happens the quickest when both of you are moving towards one another. Unfortunately if that is really the case is something you have to guess, based on the traffic patern and shoreline. I made the picture a bit more complicated because I was only interested in those situations where the target could only be found with hydrophones. If you want to keep it simple just take 2 times the maximum hydrophone range (2*34km, or 2*18.3nm), and divide that by the combined speed of you both. Then you have the amount of hours the target stays inside your detection range. To notice him you have to do a hydrophone check at least once in that time interval. But only if you do the hydrophone checks manually. If you let the crew do the listening the range is only 20km or so, and would require even shorter periods of time. Also if the target happends to just skim the detection range then he only spends a very small period of time in that detection area. I gave the formula to calculate the length of the track if the target when the target maintains a certain minimal range. Then the time becomes significantly shorter.