diff --git a/rowers/datautils.py b/rowers/datautils.py
index dda402c0..68efe7a5 100644
--- a/rowers/datautils.py
+++ b/rowers/datautils.py
@@ -365,11 +365,17 @@ def getmaxwattinterval(tt,ww,i):
 
     return deltat,wmax
 
-def getfastest(df,thedistance):
+def getfastest(df,thevalue,mode='distance'):
     tt = df['time'].copy()
     dd = df['cumdist'].copy()
 
     tmax = tt.max()
+    if mode == 'distance':
+        if dd.max() > thevalue:
+            return 0
+    else:
+        if tt.max() > thevalue:
+            return 0
 
     if tmax > 500000:
         newlen=int(tmax/2000.)
@@ -412,6 +418,10 @@ def getfastest(df,thedistance):
     restime = np.array(restime)
     distance = np.array(distance)
 
-    d2 = griddata(distance,restime,[thedistance],method='linear',rescale=True)
+    d2 = 0
+    if mode == 'distance':
+        d2 = griddata(distance,restime,[thevalue],method='linear',rescale=True)
+    else:
+        d2 = griddata(restime,distance,[thevalue],method='linear',rescale=True)
 
     return d2[0]/1000.