AC_PolyFence_loader: log fence on sucsesful write

libraries/AC_Fence/AC_PolyFence_loader.cpp

@@ -12,6 +12,7 @@
 
 #include <AP_AHRS/AP_AHRS.h>
 #include <GCS_MAVLink/GCS.h>
+#include <AP_Logger/AP_Logger.h>
 
 #include <stdio.h>
 
@@ -1180,6 +1181,9 @@ bool AC_PolyFence_loader::write_fence(const AC_PolyFenceItem *new_items, uint16_
     gcs().send_text(MAV_SEVERITY_DEBUG, "Fence Indexed OK");
 #endif
 
+    // start logger logging new fence
+    AP::logger().Write_Fence();
+
     void_index();
 
     // this may be completely bogus total.  If we are storing an