Correction ship direction

src/main/java/_9/_3/Ship.java

@@ -38,7 +38,11 @@ public class Ship extends Observable {
     }
 
     public void turnLeft() {
-        heading = (heading - 90) % 180;
+        if (heading - 90 < 0) {
+            heading = 360 + ((heading - 90) % 360);
+        } else {
+            heading = (heading - 90) % 360;
+        }
         this.setChanged();
         notifyObservers(ShipEvent.TURN_LEFT);
     }

src/main/java/_9/_3/ShipLog.java

@@ -20,11 +20,15 @@ public class ShipLog implements Observer {
                 System.out.println("Cannons fired.");
                 break;
             case TURN_LEFT:
-                heading = (heading - 90) % 180;
+                if (heading - 90 < 0) {
+                    heading = 360 + ((heading - 90) % 360);
+                } else {
+                    heading = (heading - 90) % 360;
+                }
                 System.out.println("Turned left. New heading " + heading + " degrees.");
                 break;
             case TURN_RIGHT:
-                heading = (heading + 90) % 180;
+                heading = (heading + 90) % 360;
                 System.out.println("Turned right. New heading " + heading + " degrees.");
                 break;
         }