Tides and Lake Levels

Tide Stations

When making maps from data gathered in tidal waters or from tracks gathered over multiple trips to lakes with varying water levels, track point depths need to be adjusted to compensate for changes in water levels. Track point depths within ReefMaster can be adjusted using either manually entered offset points, entered for each individual track (see Tracks), or through the use of a Tide Station.

A Tide Station is a collection of water level offset values, stored within ReefMaster, that can be used to offset the track-point depths of tracks within the workspace. Depth values between existing tide points are interpolated using a simple linear interpolation.

Data within a tide station must be imported from an external source; either from a comma-delimited text (CSV) file, or from the WXTide application.

ReefMaster does not provide tide information, nor does ReefMaster warrant that tide information imported from any suggested source is correct. Tide Station functionality within ReefMaster is simply a method of storing externally sourced tide offset data.

Lake Level Offsets

Adjusting track depths for varying lake levels typically involves using just a single depth value per track, which is most easily achieved by using adjusting the overall water level of a single track. See Tracks for more information.

Creating a new Tide Station

Tide stations are edited within the Global Settings window, which can be opened by clicking on the settings option in the File menu.

To create a new tide station, open the global settings window and navigate to the Tides tab. Click the Add button (circled, above).

The Import New Tide Station window is shown, which allows tide data to be imported from a text file or the wxtide Windows application:

1. Name and Time Zone

Choose a friendly name for the new tide station that will be used to identify the tide station within the workspace.

Set the time zone for the data to be imported, if required. Time zone is only important when importing data from text files that use local time.

2. Import source

Tide data can be imported from comma delimited text files or the WXTide32 application.

Importing Tide Data from a Text File

1. Data Source

Ensure that Text File is selected as the data source.

2. Times and Depths

Check your source data to determine whether times are stored as local or UTC times and how depths are represented, and set the Times and Depths settings appropriately.

3. Import

Click the Import button. A file selector is shown, from where the required file can be chosen. The source file can have any file extension, so long as the data is written in the correct format. By default, ReefMaster looks for files of type *.txt and *.csv.

Required Text File Format

The text file must contain one pair of values per row, in the format [TIME],[DEPTH].

·No units suffix to the depth values.

·The time can be represented in any standard format.

·There must be only one comma character per line.

·Lines that are incorrectly formatted are ignored.

After the import process has completed, the number of successfully imported tide values is displayed in the application status bar.

Importing Tide Data from WXTide

WXTide

WXTide is a free program that provides tidal predictions for many areas of the world. ReefMaster can import tide information from WXTide and save it in a tide station.

WXTide can be downloaded and installed from http://www.wxtide32.com. ReefMaster needs to know the hard-disk location of the wxtide.exe program file before it can be used. This can be done in the Global Settings or by using the Browse button (2). In a default installation, the application will be in directory “C:\Program Files\WXTide32”.

Select WXTide as the required data source, which will show the WXTide import options:

1. wxtide32.exe Location

Locate the wxtide32.exe program file on disk, as described above. This only needs to be set once, and will then be remembered for future use.

2. Tide Station List

A list box shows all of the available tide stations in the WXTide installation, from where they can be selected. To search for a tide station, type all or part of the required location name into the Search box (3).

4. Date Range

Specify the required date range for the data import. Dates can either be typed in or selected using the data picker control. Note that importing long time periods of data may take a significant amount of time.

5. Import

When the required settings have been set, start the import using the Import button.

Viewing Tide Station Data

Once data has been successfully imported into a new tide station, it can be viewed:

Tide data for a 24 hour period is shown in the graphical edit area. Move the mouse within the display area to show the interpolated depth value at any point in time. Hold the mouse pointer over a tide point to see the stored time and date value.

The displayed time period can be adjusted by year, month or day arrows, or the date selector.