Manual targeting: need an explanation.

[Maraz]

Originally Posted by ronbrewer

Thanks for that info, CaptainAsh. I'm going to give that a try this weekend. I have two questions, though, just to make sure I don't mess up the procedure:

1) Will you get the same results if the target is 2000 meters away versus 800 meters away? Basically, since the ship is smaller at 2000 meters wouldn't it travel through the crosshairs faster or is this where I'm just not understanding the physics of the procedure.

Yes same result.

2) Does it matter if you have the periscope on zoom instead of normal magnification? This question is similar to question 1 since zoom creates a larger ship image.

No, it does not matter.

Basically, if your sub is not moving and you don't move the periscope, you are looking at the same point in the sea. So you are measuring how much time the ship takes to pass that point with her whole length. This has no relation with your distance from the ship and how big she is in your scope. E.g.: if the ship is 100m long, you are measuring how many seconds she takes to make 100m. Hence you can compute speed (V) given space (S) and time (T): (V=S/T)

This does not work if the ship is coming towards you or is going away from you with a small angle, of course.

Maraz