Index: dam engine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/DamMacroStability/DamMacroStabilityKernelWrapper.cs
===================================================================
diff -u -r683 -r686
--- dam engine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/DamMacroStability/DamMacroStabilityKernelWrapper.cs	(.../DamMacroStabilityKernelWrapper.cs)	(revision 683)
+++ dam engine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/DamMacroStability/DamMacroStabilityKernelWrapper.cs	(.../DamMacroStabilityKernelWrapper.cs)	(revision 686)
@@ -27,8 +27,12 @@
         /// Prepares the specified dam kernel input.
         /// </summary>
         /// <param name="damKernelInput">The dam kernel input.</param>
-        /// <returns></returns>
-        public PrepareResult Prepare(DamKernelInput damKernelInput, out IKernelDataInput kernelDataInput)
+        /// <param name="kernelDataInput">The kernel data input.</param>
+        /// <param name="kernelDataOutput">The kernel data output</param>
+        /// <returns>
+        /// Result of the prepare
+        /// </returns>
+        public PrepareResult Prepare(DamKernelInput damKernelInput, out IKernelDataInput kernelDataInput, out IKernelDataOutput kernelDataOutput)
         {
             // TODO: this is just fake data
             const string testFolder = @"..\..\Deltares.DamEngine.Calculators.Tests\Files\MacroStability";
@@ -40,6 +44,8 @@
                 DGeoStabilityExePath = Path.Combine(DamMacroStabilityFolder, DGeoStabilityExe),
                 DGeoStabilityInputFileName = stiFileName
             };
+            kernelDataOutput = new DamMacroStabilityOutput();
+
             return PrepareResult.Successful;
         }
 
@@ -66,11 +72,11 @@
         /// Executes the kernel.
         /// </summary>
         /// <param name="kernelDataInput">The kernel data input.</param>
+        /// <param name="kernelDataOutput">The kernel data output.</param>
         /// <param name="messages">The return messages.</param>
-        /// <returns></returns>
-        public IKernelDataOutput Execute(IKernelDataInput kernelDataInput, out List<LogMessage> messages)
+        public void Execute(IKernelDataInput kernelDataInput, IKernelDataOutput kernelDataOutput, out List<LogMessage> messages)
         {
-            var damMacroStabilityOutput = new DamMacroStabilityOutput();
+            DamMacroStabilityOutput damMacroStabilityOutput = (DamMacroStabilityOutput) kernelDataOutput;
             messages = new List<LogMessage>();
 
             // ToDo zant Question: write sti file in prepare or in execute?
@@ -107,7 +113,6 @@
                     damMacroStabilityOutput.Zone2 = zone2;
                 }
             }
-            return damMacroStabilityOutput;
         }
 
         internal XDocument CreateMstabDamXmlDocument()