"Blast WeaponsWhen firing a Blast or Large Blast Weapon at a vehicle, place the marker with the hole over any part of the vehicle's hull and then roll for scatter as normal. In the case of multiple blasts, the vehicle will be hit once each time any part of a blast marker ends up over the vehicle or its base. The armour penetration roll is resolved against the Armour Value facing the firer, regardless of the position of the marker, using the full Strength of the weapon"
Image stolen from Faeit 212, enlarged and sort-of made easier to read.
Ok, so what does this mean? I know that my Manticore just got a whole lot happier! I think all IG artillery just got a huge boost, since no longer do you need to have the center hole on the hull to penetrate a vehicle. For example, a Basilisk could scatter 4" left and still hit a Chimera with its full strength. Before if it was off by 2" it would have only used half strength. Very interesting times ahead. I can't wait for my book to arrive.