Originally Posted by chris blair
The problem was with current arrows at the St Mary's entrance around Cumberland Island. In the screen shot below notice the two arrow at the entrance showing North current when it was a strong outgoing tide that should have them pointing easterly. Also notice in the ICW
west of Cumberland Island there are two opposing current arrows. I was in the channel and measured current. The outgoing arrow was correct and the incoming arrow was incorrect.
I think the root cause is in the current data. Some data do not contain a directional component and opencpn
shows them with an arrow (always in the same direction, not exactly North up? I don't know)
I looked at the Cumberland area and also see opposing current arrows.
Then I looked at the current data from NOAA for that area:
Current Station Locations and Ranges
Several current station do not have data for a direction for Ebb and flood, these seem to coincide with the arrows pointing in the wrong direction
Here an excerpt, sorry the table format got lost
in the cut'n'paste.
St. Marys River
Correct direction of the current arrow in opencpn
Fort Clinch, 0.3 n.mi. N of 50d 30° 42.6' 81° 27.2' 0.2 226 1.4 275 0.1 280 1.6 087
Fort Clinch, 1.1 n.mi. NW of 14d 30° 42.9' 81° 28.6' 0.1 214 1.3 309 0.1 067 1.9 133
Drum Point Island, Range D Channel 12d 30° 45.9' 81° 29.2' 0.1 165 1.1 350 0.1 154 1.5 170
Wrong direction of the current arrow in opencpn
Fort Clinch, 0.1 n.mi. N of 12d 30° 42.4' 81° 27.3' 0.1 - - 2.2 - - 0.2 - - 2.6 - -
Fort Clinch, 0.6 n.mi. NE of 11d 30° 42.6' 81° 26.8' 0.1 - - 2.2 - - 0.2 - - 2.7 - -
Cumberland Island, Range B Channel 22d 30° 43.9' 81° 29.1' - - - - 1.2 - - 0.1 - - 1.8 - -
I looked at maxsea
, same location. It doesn't show the current stations missing the direction. Can other users check other programs, what do they show for these locations?
I would rather keep these current station but show them differently, without the arrow.
I like ChrisBlair's Thermometer idea to show current strength within the arrow. Maybe show just the thermometer, without the arrow tip?