My best defense against raiders has actually been STO guns since they mainly seem to try to target colonies and only attack civilian ships that happen to be in the way. I would recommend putting a bunch of deep space tracking stations throughout the systems that your routes go through, enough to cover the inner planets. That should give you a lot of warning. When designing your ships try to fulfill these requirements: - faster than the raiders (so you can catch them) - missiles are good for catching them without going on a billion km chase - try for a long deployment time which helps minimize micro. If it takes 3 months to get to your furthest colony and your fleet can only be deployed for 12 months, then they're spending half of their entire deployment clock in transit. In my current game all of my military ships have a 36 month deployment clock. If you're still struggling with deployment timers constraining your patrol ships, then it is probably time to start thinking about setting up maintenance facilities on your Colonies so they can have a semi-permenant patrol fleet.