I'm a new user of OpenCPN
which I find is great.
Being in the UK I decided to try to improve the tide data coverage for the UK and was able to add secondary port data with some success from WXtide IDX files (more on this later).
What I found is that for some secondary ports
, particularly drying ports
, where the low water
data is unknown (such as Rye on UK south coast), data for low water
offsets is often entered in the IDX file as 111.1.
This seems to cause erratic tide graphs - silly HW figures - clearly in error.
OK, so I went back to the OpenCPN
installed IDX file (usr/share/opencpn/tcdata/HARMONIC.IDX) and had a look to see if any similar data is in the installed file.
I found 3 instances.
64.1333N 45.0W Minas Basin Windsor.
63.3333N 45.3667W Minas Basin Truro.
64.5833N 45.8667W Peticodiak River Hopewell.
Looking at the tidal curves in OpenCPN, the first of these doesn't seem to look too bad at first glance, the other two clearly show the problem.
Hope this makes sense.
The more info I promised later.
In adding my additional data I found that simply importing a new IDX file is not enough, there also needs to be a harmonic data file of the same name with no extension in the same directory as the IDX file.
I also found that the offset heights of data in WXtide files is in feet, but this shows as meters in OpenCPN (which uses meter offsets).