FWIW, it probably wasn't a slide rule. It was most likely a
torpedo-evasion aid: the inner disk has an own-ship image and markings
for a set of "evasion zones", the outer disk is marked with angles from
0 to 360. To use it, you set the outer disk to the ship's current
heading and set the cursor to the bearing of the torpedo. The "zone"
selected determines whether you should turn toward or away from the
torpedo, and to what heading.

Steve

> -----Original Message-----
> I was watching the movie, "The Hunt for Red October". In the
> scene where
> Baldwin is on the Red October, and the Alfa submarine
> launches a torpedo,
> Baldwin picks up a circular rule to calculate the trajectory
> of the incoming torpedo.