diff --git a/mock/src/main/java/seng302/Model/Race.java b/mock/src/main/java/seng302/Model/Race.java
index d46840f5..ed6c5a4d 100644
--- a/mock/src/main/java/seng302/Model/Race.java
+++ b/mock/src/main/java/seng302/Model/Race.java
@@ -66,7 +66,7 @@ public class Race implements Runnable {
      * Frame periods are multiplied by this to get the amount of time a single frame represents.
      * E.g., frame period = 20ms, scale = 5, frame represents 20 * 5 = 100ms, and so boats are simulated for 100ms, even though only 20ms actually occurred.
      */
-    private int scaleFactor = 30;
+    private int scaleFactor = 15;
 
     /**
      * The race ID of the course.
@@ -587,23 +587,30 @@ public class Race implements Runnable {
             boat.moveForwards(distanceTravelledMeters, updatePeriodMilliseconds * this.scaleFactor);
 
 
-            //Calculate the boat's bearing bounds, to ensure that it doesn't go out of the course.
-            Bearing[] bearingBounds = this.calculateBearingBounds(boat);
+            //Only get a new VMG if the boat will go outside the course, or X seconds have elapsed.
+            boolean willStayInsideCourse = this.checkBearingInsideCourse(boat.getBearing(), boat.getCurrentPosition());
+            long tackPeriod = 15000;
+            if (!willStayInsideCourse || (boat.getTimeSinceTackChange() > tackPeriod)) {
 
+                //Calculate the boat's bearing bounds, to ensure that it doesn't go out of the course.
+                Bearing[] bearingBounds = this.calculateBearingBounds(boat);
 
-            //Calculate the new VMG.
-            VMG newVMG = this.calculateVMG(boat, bearingBounds);
 
+                //Calculate the new VMG.
+                VMG newVMG = this.calculateVMG(boat, bearingBounds);
 
-            //If the new vmg improves velocity, use it.
-            if (improvesVelocity(boat, newVMG)) {
-                boat.setVMG(newVMG);
-            } else {
-                //We also need to use the new VMG if our current bearing will take us out of the course.
-                if (!this.checkBearingInsideCourse(boat.getBearing(), boat.getCurrentPosition())) {
+
+                //If the new vmg improves velocity, use it.
+                if (improvesVelocity(boat, newVMG)) {
                     boat.setVMG(newVMG);
-                }
 
+                } else {
+                    //We also need to use the new VMG if our current bearing will take us out of the course.
+                    if (!willStayInsideCourse) {
+                        boat.setVMG(newVMG);
+                    }
+
+                }
             }