Visualiser model thread was updating GUI instead of fx thread.

racevisionGame/src/main/java/visualiser/Controllers/RaceViewController.java

@@ -331,8 +331,8 @@ public class RaceViewController extends Controller {
 
             viewSubjects.add(shockwave);
 
-            boat.legProperty().addListener((o, prev, curr) -> swapColours(curr));
-            boat.hasCollidedProperty().addListener((o, prev, curr) -> showCollision(boat, shockwave));
+            boat.legProperty().addListener((o, prev, curr) -> Platform.runLater(() -> swapColours(curr)));
+            boat.hasCollidedProperty().addListener((o, prev, curr) -> Platform.runLater(() -> showCollision(boat, shockwave)));
         }
         // Fix initial bird's-eye position
         view3D.updatePivot(new Translate(250, 0, 210));
@@ -741,4 +741,4 @@ public class RaceViewController extends Controller {
         }
     }
 
-}
+}