Undying Ships Civic
Adds a civic that makes your fleets very difficult to damage permanantly. This is done by increasing health and health regen by a ton, but also by increasing combat disengagement change by 1000% this makes it so that even if your fleet loses a battle, it should not lose any combat stength.
Combat disengagement cannot save ships from being oneshot however. So you can still lose ships against enemies that deal high damage per shot.