What i've done is create a table for firing angles for 90 degree attacks.
The gist of it is that if you are 90 degrees ofcourse of a target and you know his speed... you dont need to ID him, nor do you need to know his range. This allows you to do rapid attacks vs. multiple ships in a convoy... to the extent that you can have multiple ships being hit almost simultaneously.
as seen in this SH3 video i made a long time ago:
http://jg52.com/gutted/sh3/Convoy.wmv
this is basically what is happening in that video (NOTE: Shooting 1 torpedo per ship is not recommended):
To pull this feat off.. all you need to do is be 90 degrees ofcourse and know his speed. The propertes of the right triangle are such that if you know both legs of it (your torpedo's speed and the ships speed).. you can easily determine any angle inside of it with a simple formula.
I've gone ahead and done the gruntwork for you (rounded to the nearest half degree):
to see it in action:
vs. a 24knot destroyer:
http://jg52.com/gutted/SH4/DD_Attack.wmv
and vs. a Convoy (also shows how to approach without being detected by the lead escort and how to escape):
http://jg52.com/gutted/SH4/ConvoyAttack_90AOB.wmv
enjoy!