This page provides an overview of the kinds of things that XTide can do. How to do them will be explained in the next section.

Icon Modes

Graph mode

San Francisco graph

Graph mode gives you a plot of the water level (or water velocity, in the case of currents) versus time. The times of high and low tide (or max flood and max ebb) are printed across the top. For currents, the times of slack water are printed across the bottom as shown below. Sunrise and sunset are denoted with different background colors. A + mark on the graph indicates the conditions at the time that the graph was generated.

Golden Gate Bridge Current graph

Clock mode

Clock mode

Clock mode is similar to graph mode, but the captions are different and the window is automatically updated once a minute to show the latest conditions. The location name is replaced by the current time, the next high tide is centered at the top and the next low tide is centered at the bottom. Dates are replaced with "High Tide" and "Low Tide" captions. In the case of currents you won't get slack water.

Classic analog tide clock If you iconify a tide clock, you will get a small "classic analog" tide clock that gives a vague idea of where you are in the tide cycle. The icon will try to update once a minute, but this does not work under some window managers.



Plain mode

Plain mode is just a plain old text listing of tide events. You get more precise heights, sunrise, and sunset times than with graph mode, and you also get moon phases which do not appear in the graph.

Washington, D.C.
38.8717° N, 77.0200° W

1998-05-31  1:02 PM EDT   3.00 feet  High Tide
1998-05-31  8:24 PM EDT   0.05 feet  Low Tide
1998-05-31  8:26 PM EDT   Sunset
1998-06-01  1:58 AM EDT   2.82 feet  High Tide
1998-06-01  5:44 AM EDT   Sunrise
1998-06-01  8:37 AM EDT   0.38 feet  Low Tide
1998-06-01  2:03 PM EDT   2.85 feet  High Tide
1998-06-01  8:27 PM EDT   Sunset
1998-06-01  9:11 PM EDT   0.15 feet  Low Tide
1998-06-01  9:44 PM EDT   First Quarter
1998-06-02  2:56 AM EDT   2.82 feet  High Tide

Calendar mode

Calendar mode basically just formats the output of plain mode into a calendar as shown below. This mode is not available from the interactive client.

February 1998
Sun 1Mon 2Tue 3Wed 4Thu 5Fri 6Sat 7
High Tide 12.54 ft
1:19 AM EST
Sunrise
6:51 AM EST
Low Tide -0.86 ft
7:30 AM EST
High Tide 12.47 ft
1:41 PM EST
Sunset
4:42 PM EST
Low Tide -1.15 ft
8:00 PM EST
High Tide 12.40 ft
2:12 AM EST
Sunrise
6:50 AM EST
Low Tide -0.56 ft
8:26 AM EST
High Tide 11.85 ft
2:37 PM EST
Sunset
4:43 PM EST
Low Tide -0.62 ft
8:55 PM EST
High Tide 12.12 ft
3:08 AM EST
Sunrise
6:49 AM EST
Low Tide -0.18 ft
9:28 AM EST
High Tide 11.20 ft
3:40 PM EST
Sunset
4:44 PM EST
First Quarter
5:55 PM EST
Low Tide -0.06 ft
9:54 PM EST
High Tide 11.80 ft
4:09 AM EST
Sunrise
6:47 AM EST
Low Tide 0.13 ft
10:35 AM EST
Sunset
4:46 PM EST
High Tide 10.67 ft
4:47 PM EST
Low Tide 0.42 ft
10:59 PM EST
High Tide 11.56 ft
5:14 AM EST
Sunrise
6:46 AM EST
Low Tide 0.26 ft
11:45 AM EST
Sunset
4:47 PM EST
High Tide 10.38 ft
5:57 PM EST
Low Tide 0.70 ft
12:05 AM EST
High Tide 11.47 ft
6:21 AM EST
Sunrise
6:45 AM EST
Low Tide 0.19 ft
12:53 PM EST
Sunset
4:49 PM EST
High Tide 10.36 ft
7:04 PM EST
Low Tide 0.76 ft
1:09 AM EST
Sunrise
6:44 AM EST
High Tide 11.53 ft
7:24 AM EST
Low Tide -0.03 ft
1:55 PM EST
Sunset
4:50 PM EST
High Tide 10.52 ft
8:05 PM EST

Banner mode

Banner mode is a specialization of graph mode for output on tractor feed dot matrix or line printers that use continuous reams of paper. The graph is turned sideways and the aspect ratio is adjusted for Pica type. This mode is only available in the command line client.

San Francisco, California
37.8067° N, 122.4650° W

-5******3****2****1****0****1****2****3****4*** 5    6    7    8    9          
******** **** **** **** **** **** **** **** **                                 
********f****f****f****f****f****f****f****f*   f    f    f    f    f          
-6******t****t****t****t****t****t****t****t    t    t    t    t    t          
******************************************                                     
****************************************   |    |    |    |    |    |          
-7************************************|    |    |    |    |    |    |          
***********************************+  |    |    |    |    |    |    |          
**********************************    |    |    |    |    |    |    |          
-8****************************** |    |    |    |    |    |    |    |          
******************************   |    |    |    |    |    |    |    |          
*****************************    |    |    |    |    |    |    |    |          
-9************************* |    |    |    |    |    |    |    |    |          
**************************  |    |    |    |    |    |    |    |    |          
*************************   |    |    |    |    |    |    |    |    |          
-10*********************    |    |    |    |    |    |    |    |    |          
************************    |    |    |    |    |    |    |    |    |1998-05-31
************************    |    |    |    |    |    |    |    |   10:35 AM PDT
-11*********************    |    |    |    |    |    |    |    |    |          
************************    |    |    |    |    |    |    |    |    |          
*************************   |    |    |    |    |    |    |    |    |          
-12***********************  |    |    |    |    |    |    |    |    |          
*************************** |    |    |    |    |    |    |    |    |          
****************************|    |    |    |    |    |    |    |    |          
-1***************************    |    |    |    |    |    |    |    |          
******************************   |    |    |    |    |    |    |    |          
******************************** |    |    |    |    |    |    |    |          
-2*******************************|    |    |    |    |    |    |    |          

Stats mode

Stats mode is for finding the highest high tide and lowest low tide within some period of time. Stats mode is only available in the command line client.

Bar Harbor, Maine
44.3917° N, 68.2050° W

Mathematical upper bound:  15.41 feet
Mathematical lower bound:  -3.99 feet
Mean Sea Level:   5.71 feet

Searched interval from 1998-01-01 12:00 AM EST to 1998-12-31 11:59 PM EST
Max was  13.86 feet at 1998-11-05 10:56 AM EST
Min was  -2.28 feet at 1998-11-05  5:20 PM EST

Raw mode

Raw mode is for getting machine-readable output that can be fed into other Unix programs. The first column is a Unix time_t timestamp (seconds since 1970-01-01 00:00Z); the second column is tide heights in whatever units were selected for the location. The start, end, and step values can be set with command line switches. This mode is only available in the command line client.

896624777 0.180580
896628377 1.271889
896631977 3.463100
896635577 6.084148
896639177 8.402840
896642777 9.943272
896646377 10.421064
896649977 9.672793
896653577 7.856022
896657177 5.543402
896660777 3.413487
896664377 1.926805
896667977 1.371479

List mode

List mode does not provide tide predictions at all; it is simply a way to get the list of supported locations from the command line client.

LocationFile Coordinates
ABA, NAGASAKI (4278)harmonics.japan32.7500° N, 129.9500° E
ABASIRI, HOKKAIDO (0118)harmonics.japan44.0167° N, 144.2830° E
Abbapoola Creek Entrance, South Carolinaharmonics32.6767° N, 80.0067° W
Abbot Point, Australiaharmonics.admiralty19.8833° S, 148.0833° E
Aberdeen, Scotlandharmonics57.1500° N, 2.0833° W
Aberdeen, Washingtonharmonics46.9683° N, 123.8533° W

Formats

XTide can render output in four different formats: X-windows, HTML, PNG, or text. The X-windows format is implicit in the interactive client and can't be selected explicitly. The others can be selected in the non-interactive client and are invoked automatically by the the interactive and web clients (e.g., when you save output to a file).

The currently supported combinations of mode and format are as follows:

Mode Legal forms
banner text
calendar text, HTML
clock X-windows
graph text, PNG, X-windows
list text, HTML
plain text, X-windows
raw text
stats text

The HTML and PNG formats are adequately demonstrated by the examples above in the Modes section. Here is an example of graph mode using the text format:

                           San Francisco, California                           
         1998-05-31                   1998-05-31           1998-05-31          
        10:36 AM PDT                  6:14 PM PDT         11:41 PM PDT         
9 ft --------------------------------------------------------------------------
                                                                               
8 ft --------------------------------------------------------------------------
7 ft --------------------------------------------------------------------------
                                                                               
6 ft --------------------------------------------------------------------------
5 ft -----------------------------------********-------------------------------
                                    ****************                           
4 ft ----------------------------***********************-------------------****
3 ft -------------------------******************************---------**********
***                         ***************************************************
2 ft*--------------------******************************************************
1 ft***---------------*********************************************************
*******+***       *************************************************************
0 ft***************************************************************************
1 ft***************************************************************************
*******************************************************************************
2 ft***************************************************************************
*******************************************************************************
7***8***9**10*11**12***1***2***3***4**5***6***7***8***9**10**11*12***1***2***3*
|***|***|***|**|***|***|***|***|***|**|***|***|***|***|***|***|*|||**|***|***|*

Here is calendar mode in the text format (note that some information is truncated to fit into 80 columns):

                                 February 1998

Sun  1     Mon  2     Tue  3     Wed  4     Thu  5     Fri  6     Sat  7     
High Tide  High Tide  High Tide  High Tide  High Tide  Low Tide 0 Low Tide 0 
1:19 AM ES 2:12 AM ES 3:08 AM ES 4:09 AM ES 5:14 AM ES 12:05 AM E 1:09 AM ES 
Sunrise    Sunrise    Sunrise    Sunrise    Sunrise    High Tide  Sunrise    
6:51 AM ES 6:50 AM ES 6:49 AM ES 6:47 AM ES 6:46 AM ES 6:21 AM ES 6:44 AM ES 
Low Tide - Low Tide - Low Tide - Low Tide 0 Low Tide 0 Sunrise    High Tide  
7:30 AM ES 8:26 AM ES 9:28 AM ES 10:35 AM E 11:45 AM E 6:45 AM ES 7:24 AM ES 
High Tide  High Tide  High Tide  Sunset     Sunset     Low Tide 0 Low Tide - 
1:41 PM ES 2:37 PM ES 3:40 PM ES 4:46 PM ES 4:47 PM ES 12:53 PM E 1:55 PM ES 
Sunset     Sunset     Sunset     High Tide  High Tide  Sunset     Sunset     
4:42 PM ES 4:43 PM ES 4:44 PM ES 4:47 PM ES 5:57 PM ES 4:49 PM ES 4:50 PM ES 
Low Tide - Low Tide - First Quar Low Tide 0            High Tide  High Tide  
8:00 PM ES 8:55 PM ES 5:55 PM ES 10:59 PM E            7:04 PM ES 8:05 PM ES 
                      Low Tide -                                             
                      9:54 PM ES