Helmsmen
Helmsmen can be recruited by spending Rank Points. 1 Helmsman will increase your defense by 1 point. Each Rank Point spent will recruit 2 Helmsmen. So spending a full levels worth of rank points can hire 10 Helmsmen (5 Rank points x 2 = 10), increasing your defense by 10.
You can also get Android Helmsmen from the Common Artifacts hourly pull.
Experimental Crate adds 4 helmsmen to your crew.
Helmsmen are included in your ship's crew that will help you in raiding enemy ships, and also help defend your ship from enemy raids.
See Also:
Engineers
Helmsmen
Scientists
Tactical Officers