TideCal Documentation

For more on TideFinder and TideCal
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TideCal is a tide computing and filtering program for Mac OS X based on the GPL licensed XTide software which is able to produce calendar compatible files for iCal and Palm Desktop. You can download it here.

Suppose you like to hike to the lighthouse at Dungeness Spit on the North Olympic Peninsula. The walk can be difficult when the tides are high. There isn't much beach, and what beach there is will be rocky and hard going. The round trip walk takes at least three hours, and usually closer to four. If you want to reach the lighthouse around low tide, you have to start an hour and a half to two hours before low tide. You may also have other constraints, like driving time or dinner engagements.

The traditional way to pick a good day to try for the hike is to scan the tide tables looking for a low tide in the late morning or early afternoon. This can be tedious. Tide tables are boring. Computers should save you work, not give you work.

How To Use TideCal

With TideFinder, you start by specifying the location. There is a search facility which searches the XTide database and lets you choose a location from the search results. Then you set up the period for the calendar, for example, all of 2005, or the summer of 2006. Then comes the fun part, you can specify which tides and other information you want for your calendar:

High Tides - You can include all the high tides with their time and height, or you can specify tides only above or below a certain height. TideCal is clever about the range, so you can specify that you only want extreme tides (e.g. below -2 or above 8) or only tides in a certain range (e.g. above 2.0 and below 3.0) by just filling in the appropriate values. You can also specify when you are interested these tides by giving a range of hours.
Low Tides - You can include all the low tides with their time and height, or you can specify tides only above or below a certain height. TideCal is clever about the range, so you can specify that you only want extreme tides (e.g. below -2 or above 8) or only tides in a certain range (e.g. above 2.0 and below 3.0) by just filling in the appropriate values. You can also specify when you are interested these tides by giving a range of hours.
Sunrise and Sunset - You can include the times of sunrise and sunset. This is especially useful for vampires, we suppose.
Moonrise and Moonset - You can include the times of moonrise and moonset. This is especially useful for werewolves.
Phases of the Moon - You can include the major phases of the moon. This is also interesting for werewolves.

TideFinder is based on XTide, but it uses the tide program, not the xtide program, so you do NOT need to have X Windows installed or running. The download includes a version of tide compiled for OS X.

Setting up TideCal

When you first start up TideCal, it should be able to find the tide program and harmonics.tcd file inside the unzipped package. If it does not, it will ask you to help find them. It will then run the tide program and build a list of all the tide stations in the database. If you have slipped in a new harmonics.tcd file, you can update this list by using the Update List button, but it is unlikely you will have to do so for some time.

The Location

The location menu usually contains all of the tide computing stations known to the software, so it is quite an awkward list. You can type a string into the Search For field and hit return and the menu will then only contain stations with names containing the string that you typed.

The Time Period

TideCal produces monthly calendars, so specify the starting month and ending month.

The High and Low Tides

You can individually select whether to include high and low tides using the checkboxes. The tide height conditions work rather sensibly, but the following table might help clarify things. Note that if both above and below heights are specified, the program does a logical OR in one case, but a logical AND in the other.

Above	Below	Condition	Tides Selected
blank	blank		Includes all tides.
specified	blank		Includes tides > above.
blank	specified		Includes tides < below.
specified	specified	above > below	Includes extreme tides which are either: tides > above or tides < below (OR case).
specified	specified	above < below	Includes tides in the range: above < tides < below (AND case).

Tide Higher Than and Tide Lower Than

There are a number of different ways to search for tides:

Specify Tide Higher Than and only tides higher than that height in feet are found.
Specify Tide Lower Than and only tides lower than that height in feet are found.
Specify Tide Higher Than with a value smaller than that for Tide lower Than and only tides between those two heights in feet are found.
Specify Tide Lower Than with a value smaller than that for Tide Higher Than and only tides that are not between those two heights in feet are found.

Tide Times

Only tides between the two times specified are included in the calendar file. To include all tides, use the default setting of tides from midnight to midnight.

Other Astronomy

TideCal can also include other sun and moon related information:

Sunrise and Sunset - two separate events. This is useful for locked in programmers who might be curious about sunlight.
Moonrise and Moonset - two separate events. This is useful for murder mystery writers, or perhaps werewolves.
Phases of the Moon - just the four primaries: Full Moon, First Quarter, Last Quarter and New Moon. This is useful for werewolves and smugglers.

Output File and Format

TideCal lets you specify the output file. If you haven't specified one when you start generating a calendar file, it will ask you for one. You can change the output file by clicking the Output Path button.

There is a pulldown menu for specifying the output format. Currently, the output formats include:

vCal - This is the iCal standard format, so the file can be imported into iCal explicitly or by double clicking it.
Palm Desktop - This is default Palm format, so the file can be imported directly into the desktop program..
Comma Separated File - This is just the date, the time and the event in a simple text format for you to use as you please.

Compute Tides

Press this button to generate the calendar file. Then, double click that file in the Finder or explicitly import it into iCal or Palm Desktop and your calendar will be full of useful information. Start planning that next vacation or expedition now!