ACTA's core system is loosely based on GW's BattleFleet Gothic. The system offers decent Star Trek conversion possibilities but you'de be far better served using a game like Starmada X, which has its own robust ship construction system. Sometimes I even think that the basic mechanics have been Trek-inspired; they work as follows: you roll to-hit, than if succesful you must roll against shields and then determine the damage. You can even design infinite combination of weapon atributes. The basic rules can be dowloaded for free at mj12games.com
"No captain kicked ass, took names, outsmarted the machines, and then scored the babes like the Kirkmeister" -Liquidator Queeg