diff --git a/mobile/com.sap.sailing.android.buoy.positioning.app/src/com/sap/sailing/android/buoy/positioning/app/ui/fragments/BuoyFragment.java b/mobile/com.sap.sailing.android.buoy.positioning.app/src/com/sap/sailing/android/buoy/positioning/app/ui/fragments/BuoyFragment.java
index 1ee3058ea85..b5d9a432e1d 100644
--- a/mobile/com.sap.sailing.android.buoy.positioning.app/src/com/sap/sailing/android/buoy/positioning/app/ui/fragments/BuoyFragment.java
+++ b/mobile/com.sap.sailing.android.buoy.positioning.app/src/com/sap/sailing/android/buoy/positioning/app/ui/fragments/BuoyFragment.java
@@ -1,25 +1,5 @@
 package com.sap.sailing.android.buoy.positioning.app.ui.fragments;
 
-import com.google.android.gms.maps.CameraUpdateFactory;
-import com.google.android.gms.maps.GoogleMap;
-import com.google.android.gms.maps.OnMapReadyCallback;
-import com.google.android.gms.maps.SupportMapFragment;
-import com.google.android.gms.maps.model.LatLng;
-import com.google.android.gms.maps.model.MarkerOptions;
-import com.sap.sailing.android.buoy.positioning.app.R;
-import com.sap.sailing.android.buoy.positioning.app.ui.activities.PositioningActivity;
-import com.sap.sailing.android.buoy.positioning.app.util.PingHelper;
-import com.sap.sailing.android.buoy.positioning.app.util.PingServerReplyCallback;
-import com.sap.sailing.android.buoy.positioning.app.valueobjects.MarkInfo;
-import com.sap.sailing.android.buoy.positioning.app.valueobjects.MarkPingInfo;
-import com.sap.sailing.android.shared.data.LeaderboardInfo;
-import com.sap.sailing.android.shared.logging.ExLog;
-import com.sap.sailing.android.shared.ui.customviews.GPSQuality;
-import com.sap.sailing.android.shared.ui.customviews.SignalQualityIndicatorView;
-import com.sap.sailing.android.shared.ui.fragments.BaseFragment;
-import com.sap.sailing.android.shared.util.LocationHelper;
-import com.sap.sailing.android.shared.util.ViewHelper;
-
 import android.Manifest;
 import android.content.BroadcastReceiver;
 import android.content.Context;
@@ -28,6 +8,7 @@ import android.content.IntentFilter;
 import android.content.pm.PackageManager;
 import android.location.Location;
 import android.location.LocationManager;
+import android.net.Uri;
 import android.os.Build;
 import android.os.Bundle;
 import android.support.v4.app.ActivityCompat;
@@ -41,6 +22,30 @@ import android.widget.Button;
 import android.widget.TextView;
 import android.widget.Toast;
 
+import com.google.android.gms.maps.CameraUpdateFactory;
+import com.google.android.gms.maps.GoogleMap;
+import com.google.android.gms.maps.OnMapReadyCallback;
+import com.google.android.gms.maps.SupportMapFragment;
+import com.google.android.gms.maps.model.LatLng;
+import com.google.android.gms.maps.model.MarkerOptions;
+import com.sap.sailing.android.buoy.positioning.app.R;
+import com.sap.sailing.android.buoy.positioning.app.ui.activities.PositioningActivity;
+import com.sap.sailing.android.buoy.positioning.app.util.DatabaseHelper;
+import com.sap.sailing.android.buoy.positioning.app.util.PingHelper;
+import com.sap.sailing.android.buoy.positioning.app.util.PingServerReplyCallback;
+import com.sap.sailing.android.buoy.positioning.app.valueobjects.MarkInfo;
+import com.sap.sailing.android.buoy.positioning.app.valueobjects.MarkPingInfo;
+import com.sap.sailing.android.shared.data.CheckinUrlInfo;
+import com.sap.sailing.android.shared.data.LeaderboardInfo;
+import com.sap.sailing.android.shared.logging.ExLog;
+import com.sap.sailing.android.shared.ui.customviews.GPSQuality;
+import com.sap.sailing.android.shared.ui.customviews.SignalQualityIndicatorView;
+import com.sap.sailing.android.shared.ui.fragments.BaseFragment;
+import com.sap.sailing.android.shared.util.LocationHelper;
+import com.sap.sailing.android.shared.util.ViewHelper;
+
+import static com.sap.sailing.domain.common.racelog.tracking.DeviceMappingConstants.URL_SECRET;
+
 public class BuoyFragment extends BaseFragment implements android.location.LocationListener, OnMapReadyCallback {
 
     private static final String TAG = BuoyFragment.class.getName();
@@ -309,9 +314,11 @@ public class BuoyFragment extends BaseFragment implements android.location.Locat
                 if (lastKnownLocation != null) {
                     MarkInfo mark = positioningActivity.getMarkInfo();
                     LeaderboardInfo leaderBoard = positioningActivity.getLeaderBoard();
+                    CheckinUrlInfo checkinUrl = DatabaseHelper.getInstance().getCheckinUrl(requireContext(), leaderBoard.checkinDigest);
+                    String secret = Uri.parse(checkinUrl.urlString).getQueryParameter(URL_SECRET);
                     helper.storePingInDatabase(getActivity(), lastKnownLocation, mark);
                     helper.sendPingToServer(getActivity(), lastKnownLocation, leaderBoard, mark,
-                            PingServerReplyCallback.class);
+                            secret, PingServerReplyCallback.class);
                     ((PositioningActivity) getActivity()).updatePing();
                     savedPosition = new LatLng(lastKnownLocation.getLatitude(), lastKnownLocation.getLongitude());
                     pingListener.updatePing();
diff --git a/mobile/com.sap.sailing.android.buoy.positioning.app/src/com/sap/sailing/android/buoy/positioning/app/util/PingHelper.java b/mobile/com.sap.sailing.android.buoy.positioning.app/src/com/sap/sailing/android/buoy/positioning/app/util/PingHelper.java
index 2831fbc5bf7..1598b15b43b 100644
--- a/mobile/com.sap.sailing.android.buoy.positioning.app/src/com/sap/sailing/android/buoy/positioning/app/util/PingHelper.java
+++ b/mobile/com.sap.sailing.android.buoy.positioning.app/src/com/sap/sailing/android/buoy/positioning/app/util/PingHelper.java
@@ -1,9 +1,8 @@
 package com.sap.sailing.android.buoy.positioning.app.util;
 
-import java.util.UUID;
-
-import org.json.JSONException;
-import org.json.JSONObject;
+import android.content.Context;
+import android.location.Location;
+import android.net.Uri;
 
 import com.sap.sailing.android.buoy.positioning.app.util.DatabaseHelper.GeneralDatabaseHelperException;
 import com.sap.sailing.android.buoy.positioning.app.valueobjects.MarkInfo;
@@ -15,22 +14,34 @@ import com.sap.sailing.android.shared.services.sending.ServerReplyCallback;
 import com.sap.sailing.domain.common.tracking.impl.FlatSmartphoneUuidAndGPSFixMovingJsonSerializer;
 import com.sap.sailing.domain.common.tracking.impl.GPSFixImpl;
 
-import android.content.Context;
-import android.location.Location;
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import java.util.UUID;
+
+import static com.sap.sailing.domain.common.racelog.tracking.DeviceMappingConstants.URL_SECRET;
 
 public class PingHelper {
     private static String TAG = PingHelper.class.getName();
 
     public void sendPingToServer(final Context context, Location location, LeaderboardInfo leaderBoard, MarkInfo mark,
-            Class<? extends ServerReplyCallback> callback) {
+            String secret, Class<? extends ServerReplyCallback> callback) {
         AppPreferences prefs = new AppPreferences(context);
         try {
             JSONObject fixJson = new JSONObject();
             fixJson.put(FlatSmartphoneUuidAndGPSFixMovingJsonSerializer.TIME_MILLIS, location.getTime());
             fixJson.put(FlatSmartphoneUuidAndGPSFixMovingJsonSerializer.LON_DEG, location.getLongitude());
             fixJson.put(FlatSmartphoneUuidAndGPSFixMovingJsonSerializer.LAT_DEG, location.getLatitude());
-            String postUrlStr = leaderBoard.serverUrl
-                    + prefs.getServerMarkPingPath(leaderBoard.name, mark.getId().toString());
+
+            Uri uri = Uri.parse(leaderBoard.serverUrl);
+            Uri.Builder builder = new Uri.Builder()
+                    .scheme(uri.getScheme())
+                    .authority(uri.getAuthority())
+                    .appendEncodedPath(prefs.getServerMarkPingPath(leaderBoard.name, mark.getId().toString()));
+            if (secret != null) {
+                builder.appendQueryParameter(URL_SECRET, secret);
+            }
+            String postUrlStr = builder.build().toString();
             context.startService(MessageSendingService.createMessageIntent(context, postUrlStr, null, UUID.randomUUID(),
                     fixJson.toString(), callback));