diff --git a/java/com.sap.sailing.domain.tractracadapter/src/com/sap/sailing/domain/tractracadapter/impl/AbstractReceiverWithQueue.java b/java/com.sap.sailing.domain.tractracadapter/src/com/sap/sailing/domain/tractracadapter/impl/AbstractReceiverWithQueue.java
index b812ae685fb..c19abc3ef40 100755
--- a/java/com.sap.sailing.domain.tractracadapter/src/com/sap/sailing/domain/tractracadapter/impl/AbstractReceiverWithQueue.java
+++ b/java/com.sap.sailing.domain.tractracadapter/src/com/sap/sailing/domain/tractracadapter/impl/AbstractReceiverWithQueue.java
@@ -121,6 +121,9 @@ public abstract class AbstractReceiverWithQueue<A, B, C> implements Runnable, Re
                 e.printStackTrace();
             }
         }
+        if (simulator != null) {
+            simulator.stop();
+        }
     }
 
     @Override
diff --git a/java/com.sap.sailing.domain.tractracadapter/src/com/sap/sailing/domain/tractracadapter/impl/Simulator.java b/java/com.sap.sailing.domain.tractracadapter/src/com/sap/sailing/domain/tractracadapter/impl/Simulator.java
index 4eb4bd0cc7b..d451fa4273b 100755
--- a/java/com.sap.sailing.domain.tractracadapter/src/com/sap/sailing/domain/tractracadapter/impl/Simulator.java
+++ b/java/com.sap.sailing.domain.tractracadapter/src/com/sap/sailing/domain/tractracadapter/impl/Simulator.java
@@ -32,6 +32,7 @@ public class Simulator {
     private WindStore windStore;
     private long advanceInMillis = -1;
     private Timer timer = new Timer("Timer for TracTrac Simulator");
+    private boolean stopped;
     
     /**
      * Creates a wind store which replays the wind store events against a tracked race, correcting the wind fixes with
@@ -70,6 +71,9 @@ public class Simulator {
                 @Override
                 public void run() {
                     for (Wind wind : windSourceAndTrack.getValue().getRawFixes()) {
+                        if (stopped) {
+                            break;
+                        }
                         trackedRace.recordWind(delayWind(wind), windSourceAndTrack.getKey());
                     }
                 }
@@ -77,6 +81,10 @@ public class Simulator {
         }
     }
     
+    public void stop() {
+        stopped = true;
+    }
+    
     private Wind delayWind(Wind wind) {
         TimePoint delayedTimePoint = delay(wind.getTimePoint());
         return new WindImpl(wind.getPosition(), delayedTimePoint, new KnotSpeedWithBearingImpl(wind.getKnots(), wind.getBearing()));
diff --git a/java/com.sap.sailing.domain/src/com/sap/sailing/domain/tracking/impl/TrackedRaceImpl.java b/java/com.sap.sailing.domain/src/com/sap/sailing/domain/tracking/impl/TrackedRaceImpl.java
index 9450cc7245b..01e64bcf222 100755
--- a/java/com.sap.sailing.domain/src/com/sap/sailing/domain/tracking/impl/TrackedRaceImpl.java
+++ b/java/com.sap.sailing.domain/src/com/sap/sailing/domain/tracking/impl/TrackedRaceImpl.java
@@ -329,7 +329,9 @@ public abstract class TrackedRaceImpl implements TrackedRace, CourseListener {
     }
 
     protected void invalidateMarkPassingTimes() {
-        markPassingsTimes.clear();
+        synchronized (markPassingsTimes) {
+            markPassingsTimes.clear();
+        }
     }
 
     /**
@@ -481,45 +483,49 @@ public abstract class TrackedRaceImpl implements TrackedRace, CourseListener {
 
     @Override
     public Iterable<Pair<Waypoint, Pair<TimePoint, TimePoint>>> getMarkPassingsTimes() {
-        if (markPassingsTimes.isEmpty()) {
-            int wayPointNumber = 1;
-            // Remark: sometimes it can happen that a mark passing with a wrong time stamp breaks the right time order
-            // of the waypoint times
-            Date previousLegPassingTime = null;
-            for (Waypoint waypoint : getRace().getCourse().getWaypoints()) {
-                TimePoint firstPassingTime = null;
-                TimePoint lastPassingTime = null;
-                if (wayPointNumber == 1) {
-                    // For the first leg the use of "firstPassingDate" is not correct,
-                    // because boats can pass the start line before the actual start;
-                    // therefore we are using the calculated start time here
-                    firstPassingTime = getStartOfRace();
-                } else {
-                    NavigableSet<MarkPassing> markPassings = getMarkPassingsInOrderAsNavigableSet(waypoint);
-                    if (markPassings != null && !markPassings.isEmpty()) {
-                        // ensure the leg times are in the right time order; there may perhaps be left-overs for marks to be
-                        // reached later that
-                        // claim it has been passed in the past which may have been an accidental tracker read-out;
-                        // the results of getMarkPassingsInOrder(to) has by definition an ascending time-point ordering
-                        synchronized (markPassings) {
-                            for (MarkPassing currentMarkPassing : markPassings) {
-                                Date currentPassingDate = currentMarkPassing.getTimePoint().asDate();
-                                if (previousLegPassingTime == null || currentPassingDate.after(previousLegPassingTime)) {
-                                    firstPassingTime = currentMarkPassing.getTimePoint();
-                                    previousLegPassingTime = currentPassingDate;
-                                    break;
+        synchronized (markPassingsTimes) {
+            if (markPassingsTimes.isEmpty()) {
+                int wayPointNumber = 1;
+                // Remark: sometimes it can happen that a mark passing with a wrong time stamp breaks the right time
+                // order of the waypoint times
+                Date previousLegPassingTime = null;
+                for (Waypoint waypoint : getRace().getCourse().getWaypoints()) {
+                    TimePoint firstPassingTime = null;
+                    TimePoint lastPassingTime = null;
+                    if (wayPointNumber == 1) {
+                        // For the first leg the use of "firstPassingDate" is not correct,
+                        // because boats can pass the start line before the actual start;
+                        // therefore we are using the calculated start time here
+                        firstPassingTime = getStartOfRace();
+                    } else {
+                        NavigableSet<MarkPassing> markPassings = getMarkPassingsInOrderAsNavigableSet(waypoint);
+                        if (markPassings != null && !markPassings.isEmpty()) {
+                            // ensure the leg times are in the right time order; there may perhaps be left-overs for
+                            // marks to be reached later that
+                            // claim it has been passed in the past which may have been an accidental tracker read-out;
+                            // the results of getMarkPassingsInOrder(to) has by definition an ascending time-point
+                            // ordering
+                            synchronized (markPassings) {
+                                for (MarkPassing currentMarkPassing : markPassings) {
+                                    Date currentPassingDate = currentMarkPassing.getTimePoint().asDate();
+                                    if (previousLegPassingTime == null
+                                            || currentPassingDate.after(previousLegPassingTime)) {
+                                        firstPassingTime = currentMarkPassing.getTimePoint();
+                                        previousLegPassingTime = currentPassingDate;
+                                        break;
+                                    }
                                 }
                             }
                         }
                     }
+                    Pair<TimePoint, TimePoint> timesPair = new Pair<TimePoint, TimePoint>(firstPassingTime,
+                            lastPassingTime);
+                    markPassingsTimes.add(new Pair<Waypoint, Pair<TimePoint, TimePoint>>(waypoint, timesPair));
+                    wayPointNumber++;
                 }
-                Pair<TimePoint, TimePoint> timesPair = new Pair<TimePoint, TimePoint>(firstPassingTime, lastPassingTime);
-                markPassingsTimes.add(new Pair<Waypoint, Pair<TimePoint, TimePoint>>(waypoint, timesPair));
-                wayPointNumber++;
             }
+            return markPassingsTimes;
         }
-
-        return markPassingsTimes;
     }
 
     @Override