World Tide 2009 - No Longer Available

World Tide 2009 • Contains 1 year worth of tide predictions • No Internet Connection Required • 7 day tide graph based on the current time • Built in map for easy port selection • Detailed high/low tide event list • Sun / Moon graph with moon phases • Choose between meters or feet • Uses GPS or other location services when available.

World Tides was written from scratch especially for the iPhone and iPod Touch. It is an entirely self contained tide prediction application that you can use anywhere.

Warning: Tide Prediction software is not perfect. It does not account for storms, shoals, wind, geographical changes, or other common events. Therefore, you should not rely on this software or any other tide prediction software for navigational purposes.

New Features

If you see a feature that I am missing and would like me to add it. Then send me an email and I'll do my best to accommodate your wish. Please don't give me a bad rating just because the application does not have a feature that you want. Bad ratings cause the sales to go down and that means I won't have the money to add new features.

A: Nope. But, if you have location services enabled, you can use it to location your position on the map.

A: Yes! There are over 5000 stations world wide. For a complete list, CLICK HERE.

Q: Are the tide predictions accurate?

A: Most of the time, they are within a few percent. The tide predictions are based on station harmonic constants and date fact factors. It is based on real-world measurements and it can be very accurate at times. However, no tide prediction software can account for things like storms or natural disasters. And these predictions vary slightly from those of other tide prediction software. Also note that the high and low tide levels are rounded to the nearest 1/10th of an hour.

Q: Can I get more than 7 days of predictions?

A: Nope. My license agreement prohibits predictions of more than 6 days plus the current day. To get more than that, I would have had to raise the price well beyond what most people would want to pay. This software is intended to meet the needs of the great majority of people. Professionals may wish to pay 10 times the price or buy the Tide Chart books which contain the entire year. But, this software is limited to 7 days. Sorry.

Q: How do I reset the time?

A: Tap on the clock and the time will snap back to within 6 minutes of the current time.

Q: Does this account for daylight savings time.

A: Yes! The closest city for each tide location was used as a reference to determine if daylight savings time is observed. Adjustments are made accordingly to the graph. Take a look a few days before daylight savings time to see discontinuities in the graph. It's pretty interesting.

Q: How do I select a station?

A: Dragging the map with your finger will change the selected port (in red) closest to the center of the screen. Zoom in by double tapping or pressing the zoom-in button if desired.

Q: What happens in 2010?

A: A Space Odyssey? Well, yes. How cool is that! But, more relevantly, the program will run out of data and you will see an expired message. Think of it like a book. Because that's essentially what it is except instead of just having tide charts which you use to calculate levels by hand, the application does it for you. If this software has enough sales, then you can bet that Tide Graph 2010 will be released as a separate product (not a free upgrade).

Q: How does it predict the moon and sun events?

A: This is done based on the lat/lon of the tide station. It uses some very complicated formulas that I can't begin to explain because I don't understand them myself. But, thanks to some very smart scientists, this software attempts to accurately predict rise and set times down to the minute.

Q: Is it possible to have two sun rise or sun sets in one day?

A: Believe it or not, YES! And you don't even need a daylight savings time event to happen. I'm afraid you'll have to google for more details, but the software was written to handle this occurrence. I'm fairly certain I got it right.

Q: What are the shaded areas for in the Moon/Sun bar?

A: Black = Night with no moon, Gray = Night with a moon, Blue = Day with no moon, Light Blue = Day with a moon. This bar is intended for a quick glance at the day. For details, just hit the Details tab at the bottom.

Q: Why does Tide Graph have more US stations?

A: Because Tide Graph uses an entirely different set of data. World Tide licenses its data from a different source.

Q: Can you add more tides to the software?

A: Sorry. I have no control over the list of tide stations. But, there are nearly 5000 stations to choose from. Try writing your local hydrological office and ask them to set up measurement stations for more tide locations.

A: Good question. I don't have the list posted yet, but I will soon. I promise. Until then, you can go to the UKHO's website at http://easytide.ukho.gov.uk/ and look at their free predictions. At the time of this release, they use the exact same stations (to the best of my knowledge).

Q: Are upgrades Free?

A: Yes. But upgrades don't include more data. They will be for bug fixes only. The application is very feature rich, so any feature suggestions will be considered for next year.

Q: How did you do the map software?

A: Well, I had the fortunate experience of writing a Google Maps clone in JavaScript a couple of years ago. So, I took those learned lessons and incorporated them into Objective C. Nearly 2000 tiles of various zoom levels were generated from a php application based on public domain shoreline data. Highly optimized images and other techniques were used to reduce the size so it wouldn't take much memory. After all, the software's job is to predict tides and the map is just a means of picking stations.

Q: Why can't I pick a station by name or by country/state/city drill down list?

A: Because it's just too hard! And it's not the iPhone way! I tried doing this at first but it took forever to find a the closest station. Then I spent weeks creating a map interface because I was so dissatisfied with the list approach. Now you can find stations in seconds! And you might even discover a few that you didn't even know about. I found one off the coast near where I live that I didn't even know existed!

Q: Why isn't my question on this list?

A: Because you haven't asked me yet. :-)  Just email me at and I'll try to answer it and post it on this website so others can take advantage of the knowledge.

2. While panning when zoomed all the way out, the map takes about one second to redraw itself after you let go. That is because it has to draw nearly 5000 stations on the map when it refreshes. So, avoid moving the graph in short stokes at minimum zoom and it will work great for you.

3. The map software does not use pinching and zooming. Instead it uses double tap and two finger tap. This is much easier to do than pinching. It might not be as cool but it's faster.

4. The times on the tide graph are determined by the change of the slope of the graph which has points every 6 minutes. So, these times tend to be about 3 minutes later than they should be. The tide heights are also determined the same way so they can be off by a percent or two. Of course, the predictions are only within 10% to 20% in ideal conditions at the exact location of the stations assuming that the station has accurate harmonic constitutes. But, I suppose I should not add any more error to an already inaccurate prediction.

5. The time of day marker drawn on the graph represents the local time on your device. It should be adjusted to match the local time of the port. In 99.9% of normal use cases, these are one in the same. But, if you look at tides in different time zones than you're at, the time of day marker is not useful.

Unknown Bugs

Have your found any other problems? Please email me at and I'll do my best to fix them right away!