diff --git a/calcs/vmg_wind.js b/calcs/vmg_wind.js
index e9da3ec..53b731e 100644
--- a/calcs/vmg_wind.js
+++ b/calcs/vmg_wind.js
@@ -9,11 +9,7 @@ module.exports = function (app) {
     ],
     calculator: function (trueWindAngle, speedOverGround) {
       var vmg_wind = Math.cos(trueWindAngle) * speedOverGround
-      if (vmg_wind < 0) {
-        return [{ path: 'performance.velocityMadeGood', value: vmg_wind }]
-      } else {
-        return [{ path: 'performance.velocityMadeGood', value: vmg_wind }]
-      }
+      return [{ path: 'performance.velocityMadeGood', value: vmg_wind }]
     }
   }
 }
diff --git a/calcs/vmg_wind_stw.js b/calcs/vmg_wind_stw.js
new file mode 100644
index 0000000..3dfdf6e
--- /dev/null
+++ b/calcs/vmg_wind_stw.js
@@ -0,0 +1,15 @@
+module.exports = function (app) {
+  return {
+    group: 'course data',
+    optionKey: 'vmg_Wind_STW',
+    title:
+      'Velocity Made Good to wind (based on wind.angleTrueWater and speedThroughWater)',
+    derivedFrom: [
+      'environment.wind.angleTrueWater',
+      'navigation.speedThroughWater'
+    ],
+    calculator: function (angleTrueWater, speedThroughWater) {
+      return [ { path: 'performance.velocityMadeGood', value: Math.cos(angleTrueWater) * speedThroughWater } ]
+    }
+  }
+}