Quote:
Originally Posted by Paul Riley
That is an interesting method pisces,I may practice this out in the academy later.
You mention an 'imaginary wall' through the water,in order for me to understand this concept would it be similar to an athlete as he crosses the finish line,or a horse?.You are timing him a few lengths backwards and then again as he actually crosses it?.
This method could come in handy if you are bang at 90deg to your target,as you could then accelerate ahead until he is about 130deg behind you,swing the boat round 90deg until you are perpendicular and get ready to time him? (nice).
It doesnt however sound very handy if you are miles behind your target,and you need a faster speed estimate,so you can get things rolling quicker,like your intercept run.
What do you think to the method where you draw level,and alter your own speed until you are both constant with each other?this to me sounds about the most accurate method for getting speed calculations.I would probably monitor him for about 5 mins for me to feel confident I have him.This method is also great when you have already crippled a ship or he changing course after a previous attack,and you quickly want to set up a second or finishing blow.
Good stuff mate   |
A finish line is a close analogy. However, in sports it is usually the interest to determine
when the athlete crosses the line. Not how fast he moves when he crosses the line. I don't know why they use multiple measurement locations at finish-lines, perhaps to sort out who is first and who is second or third. But luckily we don't have that problem.
During the whole process of fixed-line speed measurement the uboat only moves towards or away from the target (
along this wall), if at all. We have just one finish line being the scope line. The multiple lengths you speak of is just only one, being the actual length of the target (thus requiring identification and so ofcourse an accurate recognitionmanual). If you think of the shiplength as the tracklength, and the intersection of the stationary wall with the ship as the athlete, and the time span of move between bow and stern as start to finish, the finish-line analogy holds.
Your leveling method works if you know his course reasonably well. Otherwise it is difficult to tell if you are both on eachothers beam (90/270 degrees bearing). Visual determination of 90 AOB is a tricky subject. The above fixed-line method is less sensitive to unknown course. It works best between 30 and 150 degrees AOB, but theoretically with all degrees AOB. The problem with very small or very large AOB is that the structures prevent seeing the bow or stern. And a wide ship might show it's side passing the line before the bow-point does.
I do use a variation of your leveling method often when measuring the speed of a target I intercepted. I take the location of the map contact report as the start. And wait until it passes a line (periscope or hydrophone bearing converted to compass direction) that is perpendicular to the reported course. This line may not be completely perpendicular to the actual targetcourse (+-11 degrees) , but the time since it's start is long enough to make it insignificant.