diff --git a/lib/api/GwApi.h b/lib/api/GwApi.h
index ae18bd0..8d83a63 100644
--- a/lib/api/GwApi.h
+++ b/lib/api/GwApi.h
@@ -15,6 +15,7 @@ class GwApi{
             public:
                 double value=0;
                 bool valid=false;
+                bool changed=false; //will be set by getBoatDataValues
                 BoatValue(){}
                 BoatValue(const String &n):name(n){
                 }
diff --git a/lib/exampletask/GwExampleTask.cpp b/lib/exampletask/GwExampleTask.cpp
index f91125c..57fb613 100644
--- a/lib/exampletask/GwExampleTask.cpp
+++ b/lib/exampletask/GwExampleTask.cpp
@@ -88,8 +88,6 @@ void exampleTask(GwApi *api){
     GwApi::BoatValue *latitude=new GwApi::BoatValue(F("Latitude"));
     GwApi::BoatValue *testValue=new GwApi::BoatValue(boatItemName);
     GwApi::BoatValue *valueList[]={longitude,latitude,testValue};
-    double lastTestValue=0;
-    bool lastTestValueValid=false;
     while(true){
         delay(1000);
         /*
@@ -155,16 +153,13 @@ void exampleTask(GwApi *api){
             }
         }
         if (testValue->valid){
-            if (! lastTestValueValid || lastTestValue != testValue->value){
+            if (testValue->changed){
                 LOG_DEBUG(GwLog::LOG,"%s new value %s",testValue->getName().c_str(),formatValue(testValue).c_str());
-                lastTestValueValid=true;
-                lastTestValue=testValue->value;
             }
         }
         else{
-            if (lastTestValueValid){
+            if (testValue->changed){
                 LOG_DEBUG(GwLog::LOG,"%s now invalid",testValue->getName().c_str());
-                lastTestValueValid=false;
             }
         }
 
diff --git a/src/main.cpp b/src/main.cpp
index fb9c30f..ff74de7 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -412,12 +412,20 @@ public:
   virtual void getBoatDataValues(int numValues,BoatValue **list){
     for (int i=0;i<numValues;i++){
       GwBoatItemBase *item=boatData.getBase(list[i]->getName());
+      list[i]->changed=false;
       if (item){
-        list[i]->valid=item->isValid();
-        if (list[i]->valid) list[i]->value=item->getDoubleValue();
+        bool newValid=item->isValid();
+        if (newValid != list[i]->valid) list[i]->changed=true;
+        list[i]->valid=newValid;
+        if (newValid){
+          double newValue=item->getDoubleValue();
+          if (newValue != list[i]->value) list[i]->changed=true;
+          list[i]->value=newValue;
+        }
         list[i]->setFormat(item->getFormat());
       }
       else{
+        if (list[i]->valid) list[i]->changed=true;
         list[i]->valid=false;
       }
     }