I have been using OpenCPN
for some time and have nothing but praise for those who have made such a system freely available to the boating
I recently upgraded to 4.0 which is running on a MS Surface Pro2 with GPS
positions provided by a Globalsat BU353S4 - a pretty standard arrangement.
I have been recently cruising by day, anchored at night, and recording my track length daily, and restarting the track each night, so as to easily sum the total over a cruising holiday.
I noticed that sometimes the track length is much longer than can be real - up to 3 times the measured length - using the measuring tool on top of the track and well zoomed in.
Also the GPX as seen in the track properties window has a couple of large values - legs 0 and 345 in the attached GPX file. These survive being transferred to a desktop
3.3.2410 - my interpretation is that the GPX file is written with errors although it is hard for me to see issues with the file itself.
Tracking precision is set to medium - if that is of any consequence.
I do note also that when zoomed well in and looking at the track on the screen
, there are occasional points where the track is duplicated - the whole thing may be duplicated in fact, but several points along the track show a slight divergence between two or more legs.
With respect to the attached file, the track length showing in the tracks tab of the Route
and Mark Manager window is 91 Nm, while the measured length on the chart is 33.3 Nm (which I don't doubt). Subtracting the large values of 24.22 and 24.30 still leaves 42.48 Nm - longer than can truly be the case.
The actual tracking in use - ie vessel position on the chart on-screen - has always been completely accurate with no jumping around to indicate something with the GPS puck
Anyone else with these sorts of issues? I am always completely open to inadequate setup or something else on my part.
A small matter in an otherwise superb package - helped hugely by the enlightened approach taken by LINZ - our provider of charts
locally here in New Zealand