Quote:
Originally Posted by Johnfb
Thanks for all the advice guys. But if I fire at a ship crossing zero degrees the ship will have moved on by the time the torpedo reaches that spot will it not. So I should fire when the ship is 10 degrees from zero to hit it. Is this correct supposing my sub is dead straight and I will be firing at the side of the ship ?
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Not to jump in out of order here, but you really don't need to worry about lead if you're using the "right angle to target course" method, as I like to call it. Which, by the way, is my preferred method of attack whenever I can get away with it. Requires the target to be unaware of your presence and thus predictable, which is the one limitation of the method.
The only thing you really need to worry about is getting the target's speed and course correct.
Once you have those, you place yourself in a perpendicular (90 degrees) line to the target course. If, for instance, your target is traveling on a 90 degrees true course from left to right, you need to point your boat at a true heading of 0 degrees. (90-90=0). Trig is really your friend in a sub
Then you "unlock" the TDC, point your scope at a bearing of 0 degrees (if you're attempting a front shot, 180 if you're firing the rear tube(s)), tell the TDC that the AOB is 90 (port or starboard depending on what direction the target is traveling in relative to you) and enter the target's speed. Then you lock the TDC data in. What you've told the TDC is what the target's AOB (and therefore course) is going to be when it passes right in front of you and, if you're at right angles to that course, that will be 90 degrees. You've also told it that the target will be traveling, at that point in the future, at a speed of
x knots.
What the TDC will then do is to calculate the gyro angle (or, more simply, angle compared to the heading of your boat) the torpedo will have to travel to hit such a target. And this is where the true beauty of this method of attack comes in: When you turn your scope until the gyro angle is 0, meaning the torpedo will be set to travel straight ahead, the TDC will be set so that a target traveling across your crosshairs will be hit in the exact location that your vertical middle line of the crosshairs is
once it reaches a point directly in front of your boat.
You don't have to lead or lag the target with your scope, as long as it is on the heading where the gyro reads 0 AND you got your course and speed calculations right. In a perfect world where you nailed both, all you have to do is to fire the torp when the vertical middle line is over wherever you want to hit the target. And here's the bonus: Distance of the target doesn't matter! Because the TDC already compensated for that with this method. You can empty your entire load of eels this way as the targets lumber across your sights. As long as the gyro reads 0 for your periscope bearing.
Of course, humans being human, as I've learned from bitter personal experience
, no speed and course fixes are ever perfect, so I personally prefer to aim not too far off the middle.
And again: This method only works for that great shot where you have the luxury of just waiting for the target to come to you at right angles to your boat's heading. For any snap decisions at oblique angles, you'll have to dig out your other tools too.