diff --git a/src/RideMetric.cpp b/src/RideMetric.cpp
index ff6ca1aa4..ed9ef879e 100644
--- a/src/RideMetric.cpp
+++ b/src/RideMetric.cpp
@@ -111,8 +111,9 @@
 // 105 09  May 2015 Ale Martinez       Added PeakPace and PeakPaceSwim metrics
 // 106 09  May 2015 Mark Liversedge    Added MMP Percentage - %age of power for duration vs CP model
 // 107 29  May 2015 Mark Liversedge    Added AP as percent of maximum
+// 108 29  Jun 2015 Mark Liversedge    Added W' Power - average power contribution from W'
 
-int DBSchemaVersion = 107;
+int DBSchemaVersion = 108;
 
 RideMetricFactory *RideMetricFactory::_instance;
 QVector<QString> RideMetricFactory::noDeps;
diff --git a/src/WPrime.cpp b/src/WPrime.cpp
index 574c8bd16..a79832a20 100644
--- a/src/WPrime.cpp
+++ b/src/WPrime.cpp
@@ -721,6 +721,47 @@ class WPrimeExp : public RideMetric {
     RideMetric *clone() const { return new WPrimeExp(*this); }
 };
 
+class WPrimeWatts : public RideMetric {
+    Q_DECLARE_TR_FUNCTIONS(WPrimeWatts);
+
+    public:
+
+    WPrimeWatts()
+    {
+        setSymbol("skiba_wprime_watts");
+        setInternalName("W' Watts");
+    }
+    void initialize() {
+        setName(tr("W' Power"));
+        setType(RideMetric::Total);
+        setMetricUnits(tr("watts"));
+        setImperialUnits(tr("watts"));
+        setPrecision(0);
+    }
+    void compute(const RideFile *r, const Zones *zones, int zonerange,
+                 const HrZones *, int,
+                 const QHash<QString,RideMetric*> &,
+                 const Context *) {
+
+        int cp = r->getTag("CP","0").toInt();
+        if (!cp && zones && zonerange >=0) cp = zones->getCP(zonerange);
+
+        double total = 0;
+        double secs = 0;
+        foreach(const RideFilePoint *point, r->dataPoints()) {
+            if (cp && point->watts > cp)  {
+                total += r->recIntSecs() * (point->watts - cp);
+                secs += r->recIntSecs();
+            }
+        }
+        setValue(total/secs);
+        setCount(secs);
+    }
+
+    bool canAggregate() { return false; }
+    RideMetric *clone() const { return new WPrimeWatts(*this); }
+};
+
 class CPExp : public RideMetric {
     Q_DECLARE_TR_FUNCTIONS(CPExp);
 
@@ -773,6 +814,7 @@ static bool addMetrics() {
     RideMetricFactory::instance().addMetric(MaxMatch());
     RideMetricFactory::instance().addMetric(WPrimeTau());
     RideMetricFactory::instance().addMetric(WPrimeExp());
+    RideMetricFactory::instance().addMetric(WPrimeWatts());
     RideMetricFactory::instance().addMetric(CPExp());
     return true;
 }