Tagan, you DO realize that VUs represent a distance of several thousand kilometers, and space is three dimensional, right?  Even though the enemy ship is dead ahead within 1 VU, it's a miniscule course correction to dodge.  Ramming an enemy ship is something you really have to TRY to do.  (Basically, much like the rules in battlefleet gothic, ships can easily occupy the same space without hitting each other, and freely travel and shoot through each other without difficulty.  In Rogue Trader, you can even shoot through enemy ships to get the one you really want, unless they're in a squadron)<br/><br/>Now as for the ship doing crazy things...  They have the mark of Slaanesh.  This particular warship class is known for engaging in suicide missions with distressing frequency.  (The Battlefleet Gothic version of the ship is famous for almost never surviving a battle, due to spending the majority of its time embedded in the enemy flanks)