For starters assume that you know target course.
Why? Because there is a bearings only method that allows you to do so. Implementable via passive means (sonar or optical observations no radar required). You won't like it though, as the sub must remain stationary as it collects data (at least three distinct bearing/time observation pairs). But if the target' is a medium or slow "mover" and you detect him early enough you may have time both for proper data collection
and maneuvering.
{ I realy think you must go through this link:
http://www.archive.org/details/maneuveringboard00unit }
Then you'll have to deal only with target's speed inaccuracies as range probably doesnt matter for small torpedo gyro angles.
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