French movie action drama on a SSN : Le chant du Loup (The Wolf's Call)

[UglyMowgli]

Originally Posted by US IRON

RE
< Magic points are an interesting idea. I am not sure how a boomer could know its position over sea floor terrain without using an active sensor to "look">

I know zero about real world submarine navigation and I suppose it is classified, but Inertial Navigation Systems INS have been around for decades. It was standard on the 747 and other airliners before Satellite GPS. Using sensitive gyroscopes and acceleromotors (force sensors) which calculate distances, velocities and accelerations a submarine would know its position fairly accurately without need of any external references, except some initialisation point when setting the system initially and checking its accuracy. On aircraft the initialisation point on startup is the gate which is a known coordinate. Maybe they utilise magnetic fields as well?

I expect all submarines would have back-up systems like this to cross-check with other more accurate systems. I have no-idea what a magic point is.

An INS drift after some time even the laser one, what is good for an airliner flying for few hours is not for a sub navigating under the sea for months. they need to re-calibrate their position. there is few methods
- GPS but need to have a signal (and during a war, well don't count on it)
- Old sextant method, need time and like the GPS method need to be on periscope depth - too dangerous during a war/crisis


- Using a distinctive seafloor topography (a big rock in the middle of a flat) or a shipwreck whose exact location is well known. This is the magic point. And to find it, there is few systems like a XXXXX or a XXXXX - sorry this is classified


And since nobody talk about, the title of the movie Wolf call refer to the sound of an active low frequency sonar using modulation to bypass the target distance ambiguity. This sound is like a wolf howling.