I agree the GTVA needs faster ships, if they're fast enuf, when the sathanas fires it could already be out of the way cuz the sathanas don't got slashers, they can't adjust the angle of the beam while its firing, and the GTVA vessel could fly in behind it and just start firing BFGreens at it. And also Cloaking technology would be of an incredible advantage too. Plus a fleet of these such vessels would IMO would mean the defeat of the Shivans, but as history shows, they always have something up their sleeves... if they have sleeves, then again the Human species is incredibly resilient.
------------------
Kryten - "They've taken Mr Rimmer, Sir! they've taken Mr Rimmer!"
Cat - "Quick, lets get out of here before they bring him back!"