Tides and Currents

Notes

Tide and Current predictions are not available for all areas.
As with all predictions, the displayed values are calculated using mathematical models and actual tides and currents will vary

Click the toolbar button to see tide stations.
Select to see current stations.
Important: tide and currents will not be displayed unless these toolbar buttons are selected.

Available tide stations will show on the chart as green graphs with a "T" logo:
The "T" becomes a yellow and blue vertical bar when the scale is greater than 1:500.000

The vertical bar contains a lot of information at a glance.
The tidal rise is 2.5m above the chart datum. The blue part is "water". The "V" inside he bar indicates that the tide is decreasing towards Low Water.
Here, the tide is rising towards High Water.
Low Water looks like this.
High Water Looks like this.
Right click the middle of either icon to see the tidal graph:

The Yellow box, with the tidal rise and time, follows the cursor when hovering over the dialog. The time axis at the bottom displays the time, in this case he timezone is "Z +01:00", which is the same as one hour ahead (east) of UTC, that used to be called GMT.
In North America it is common to use a three or four letter acronym for timezones.

CODE	UNITED STATES TIME ZONE CODES	UTC OFFSET
AST	ATLANTIC STANDARD TIME	UTC - 4
EST	EASTERN STANDARD TIME	UTC - 5
EDT	EASTERN DAYLIGHT TIME	UTC - 4
CST	CENTRAL STANDARD TIME	UTC - 6
CDT	CENTRAL DAYLIGHT TIME	UTC - 5
MST	MOUNTAIN STANDARD TIME	UTC - 7
MDT	MOUNTAIN DAYLIGHT TIME	UTC - 6
PST	PACIFIC STANDARD TIME	UTC - 8
PDT	PACIFIC DAYLIGHT TIME	UTC - 7
AKST	ALASKA TIME	UTC - 9
AKDT	ALASKA DAYLIGHT TIME	UTC - 8
HAST	HAWAII-ALEUTIAN STANDARD TIME	UTC - 10
HADT	HAWAII-ALEUTIAN DAYLIGHT TIME	UTC - 9
SST	SAMOA STANDARD TIME	UTC - 11
SDT	SAMOA DAYLIGHT TIME	UTC - 10
CHST	CHAMORRO STANDARD TIME	UTC +10

Available current stations will show on the chart as orange diamonds, when zooming in arrows will appear pointing in the direction of the set. Note that "current" here is the same as the UK term "tidal stream".
Master current stations are shown like this in all scales. No direction is associated with these stations but they can be queried, trough a right click, for the magnitude of the current.

Arrow indicates current direction and strength - the bigger the arrow, the more current.
The size of the arrows can be customized by users in the opencpn.ini (opencpn.conf) file.
In the [Settings/Others] section you can set the option CurrentArrowScale to a positive number representing a percentage scaling factor of the current arrows. The values bellow 100 mean the arrows will be smaller than now, the values above 100 will cause them to be bigger.
Right click the orange box to see current graph:

The Yelow box, with time,speed and direction, follows the cursor when hovering over the dialog.

The default dataset for tides and currents is limited, mainly for copyright reasons.
A number of different datasets are available on the Internet, with vastly greater coverage. Some of this data is getting aged, and they also contains glitches and errors, many of which has been corrected in the default dataset.
In many areas there are no free alternatives, and OpenCPN makes it possible to quickly switch between data sets.
Create a folder UserTCData in your user data folder. Under this subfolder you can then create any number of subfolders, each containing the HARMONIC/HARMONIC.IDX file pair with different data. It will look something like this
Go to Toolbox->Settings->Tides & Currents. The button to the right will now look like this:
To use a different dataset than the default, simply click it.