The faster you go, the more noise you make. It would be easier for the passive seeker head on the torpedo to hear you and home in on your boat....especially if you cavitate. One tactic you can try is going slow and silent if you can to try and avoid attracting the passive seeker and sneak out of its acquisition range. Just make sure there are no torps in the area and its not too risky to go slow....especially active homing torps that don't care how quiet you are.
