Thanks geo and sj. That's a start. Maybe destroyed engines are only MOSTLY dead. And I like the idea about every ship having basic deflector tech, which also must be lowered to board. Maybe destruction of other ships comes about due to electronic control system overload by a high energy electromagnetic pulse (HEEMP) from the SDD. The military used to worry about HEEMPs from atmospheric nukes back in the cold war days. What a relief that we don't have to worry about nukes anymore, since it was only the Soviets who'd ever do anything like that.
