Index: DamEngine/trunk/src/Deltares.DamEngine.Data/Geometry/GeometrySurface.cs
===================================================================
diff -u -r7044 -r7045
--- DamEngine/trunk/src/Deltares.DamEngine.Data/Geometry/GeometrySurface.cs	(.../GeometrySurface.cs)	(revision 7044)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data/Geometry/GeometrySurface.cs	(.../GeometrySurface.cs)	(revision 7045)
@@ -178,14 +178,20 @@
         const double stopCriteriumOffset = 1e-8;
         double offset = initialOffset;
         Point2D point = null;
-        var geometryPointString = DetermineTopGeometrySurface();
+        GeometryPointString geometryPointString = DetermineTopGeometrySurface();
         geometryPointString.SortPointsByXAscending();
         while (point == null && offset > stopCriteriumOffset)
         {
             // Just keep looking by halving the offset until found.
             point = FindValidTestPoint(geometryPointString, offset);
             offset /= 2.0;
         }
+        
+        // if no valid point is found (this can happen in case of very thin layer), try using the centroid of the outer loop
+        if (point == null && InnerLoops.Count == 0)
+        {
+            point = Routines2D.ComputeCentroid(geometryPointString.Points);
+        }
         return point;
     }