The propulsion system is nicknamed "Caterpillar Drive", and makes sonar detection extremely difficult.

The actual mechanics of sonar detection and layers in the ocean were explained in a mathematical formula known as Snell's Law.

Highly variable bottom paths, biologics, and other factors complicate sonar detection.

Its chances of sonar detection by the Seawitch were regarded as extremely small.

The trick was to balance the advantage of using the Petlyura's high speed to get through the blockade quickly against the increased risk of sonar detection.

He explained, however, that the jetmarine's transparent nose pane-which had to be left unprotected for the pilot's visibility- offered one vulnerable spot to sonar detection.

The next morning he eagerly tackled the job of adding sonar protection and sonar detection features to his electronic hydrolung.

This would provide an adequate surface target for active sonar detection and tracking in the irregular contours and the varying wind driven thermal gradients.

The fact that the underside had been struck suggested a submarine attack that had somehow eluded sonar detection.

It continues deep inside the mountain in an underwater cave never fully explored, as its end seems impossible to trace even by employing sonar detection.