It's a maneuver by a Russian sub to throw off any one trying to follow.
It involves a bunch of radical course and depth changes.
(Capt. Marko Ramias Used it in the IGUK GIUK gap when he defected with the Krasny Oktobre )
Something I've witness (acoustically) on a hundred occasions. The "I" in GIUK is Iceland where I spent a year chasing Ivans for a living. The others are Greenland and the United Kingdom...
Also called "clearing the baffles", it's actually a 90-180 course change to port or starboard to check for enemy subs that might be following as the sonar equipment is mounted in the bow of the boat. What Tom refers to is called "angles and dangles" which was used to shake a tailing submarine!
Remember Tom, Hunt for Red October is a work of fiction, nothing more! Clancy was not too sure of what he was speaking about at that time. He gained a bit of intel after the publishing of that novel and the following books were better, at least technically!