diff --git a/Projekte/battleship/model/src/main/java/pp/battleship/game/server/ServerGameLogic.java b/Projekte/battleship/model/src/main/java/pp/battleship/game/server/ServerGameLogic.java
index a5987fa..4a6642d 100644
--- a/Projekte/battleship/model/src/main/java/pp/battleship/game/server/ServerGameLogic.java
+++ b/Projekte/battleship/model/src/main/java/pp/battleship/game/server/ServerGameLogic.java
@@ -134,6 +134,7 @@ public class ServerGameLogic implements ClientInterpreter {
 
     /**
      * Handles the reception of a MapMessage.
+     * Also tests valid ship placement on the Map.
      *
      * @param msg  the received MapMessage
      * @param from the ID of the sender client
@@ -142,7 +143,15 @@ public class ServerGameLogic implements ClientInterpreter {
     public void received(MapMessage msg, int from) {
         if (state != ServerState.SET_UP)
             LOGGER.log(Level.ERROR, "playerReady not allowed in {0}", state); //NON-NLS
-        else
+
+        List<Battleship> ships = msg.getShips();
+
+        if (!shipsValid(ships)){
+            LOGGER.log(Level.ERROR, "ship placement by player {0} is Invalid", from);
+            send(getPlayerById(from),null);
+            return;
+        }
+
             playerReady(getPlayerById(from), msg.getShips());
     }
 
@@ -217,4 +226,39 @@ public class ServerGameLogic implements ClientInterpreter {
             }
         }
     }
+    /* Tests if a given ship is positioned inside of Map constrains
+    *
+    */
+
+    private boolean isInBounds(Battleship ship){
+        return ship.getMinX() >= 0 && ship.getMaxX() < config.getMapWidth() &&
+               ship.getMinY() >= 0 && ship.getMaxY() < config.getMapHeight();
+    }
+
+
+    /* Tests if a ship occupies the space of another ship and marks occupied points in the Map.
+     *
+     */
+    private boolean shipsValid(List<Battleship> ships) {
+
+        Set<IntPoint> occupied = new HashSet<>();
+
+        for (Battleship ship : ships) {
+            if (!isInBounds(ship)){
+                return false;
+            }
+            for (int x = ship.getMinX(); x <= ship.getMaxX(); x++) {
+                for (int y = ship.getMinY(); y <= ship.getMaxY(); y++) {
+                    IntPoint point = new IntPoint(x,y);
+                    if (!occupied.add(point)){
+                        return false;
+
+                    }
+
+                }
+            }
+        }
+        return true;
+    }
+
 }