April 13, 2013 01:42
Earlier this week we sailed from Marsh Harbour Bahamas to Daytona Beach Florida going NW through the Abacos. We departed for Florida from an anchorage at Strangers Cay.
We noticed that a waypoint created on the Wavey Line chart Ab - Strangers Cay to Carters Cay = B34 was displaced seven miles or so to the ENE on the Wavey Line Grand Bahamas Overall Chart B148B.
The vessel position and track showed correctly on the Strangers Cay chart, but was again consistently displaced on the larger scale chart. It looked like we were sailing thru land when in ten feet of water on the Grand Bahamas Overall chart.
However, the waypoint appeared normally on the NOAA USA East Charts and the lat long at the waypoint agreed with both my iPad, on board GPS units and of course visual sights.
Other Bahamian waypoints appeared normally on various scaled Wavey Line charts so perhaps the anomaly is limited to this chart group.
Also, the Wavey Line aren't as functional in iNavX as the NOAA charts, i.e no quilting or easy access to different scale charts, and are no substitute for the printed Explorer Charts.
This was our first use of this software, so perhaps there was user error. However, we reset and messed with this waypoint multiple times and the position offset repeated itself every time, and the problem did not replicate for other waypoints on other charts.
The lesson of course is to keep you head out of the cockpit and trust your eyes not some computer.
But if you are transiting Strangers Cut with this software please be very, very careful.
Cap'n John
We noticed that a waypoint created on the Wavey Line chart Ab - Strangers Cay to Carters Cay = B34 was displaced seven miles or so to the ENE on the Wavey Line Grand Bahamas Overall Chart B148B.
The vessel position and track showed correctly on the Strangers Cay chart, but was again consistently displaced on the larger scale chart. It looked like we were sailing thru land when in ten feet of water on the Grand Bahamas Overall chart.
However, the waypoint appeared normally on the NOAA USA East Charts and the lat long at the waypoint agreed with both my iPad, on board GPS units and of course visual sights.
Other Bahamian waypoints appeared normally on various scaled Wavey Line charts so perhaps the anomaly is limited to this chart group.
Also, the Wavey Line aren't as functional in iNavX as the NOAA charts, i.e no quilting or easy access to different scale charts, and are no substitute for the printed Explorer Charts.
This was our first use of this software, so perhaps there was user error. However, we reset and messed with this waypoint multiple times and the position offset repeated itself every time, and the problem did not replicate for other waypoints on other charts.
The lesson of course is to keep you head out of the cockpit and trust your eyes not some computer.
But if you are transiting Strangers Cut with this software please be very, very careful.
Cap'n John