For some boaters tides and currents are something to think about only rarely. For others, they are a constant concern. Our home port is on Penobscot Bay in Maine – the land of the 10-foot tides – so we think about them every time we step aboard.
No matter where your home port is, if you spend enough time on the water, you will need to think about tides and currents – and these considerations can be critical. They can save fuel costs and time, but they can also impact safety when entering an ocean inlet or docking in an unfamiliar port.
While checking tide and current predictions is traditionally done using tide tables, today there are many great options that allow you to enter a location and receive the predictions electronically on your laptop or smartphone. We like using the phone because, like weather or navigation information, this data is nice to have in your pocket.
Indeed, there are few pieces of information that are more practical. For example, tidal information can be useful in almost any anchoring situation. In Maine, knowing how high the tides are and where you are in the tide cycle is a requirement. Fail to include the 10-foot tide in your scope calculations and you could drag the anchor in the middle of the night or even go aground.
Tide Tool is free, reliable, covers almost 7,000 locations and has a smart graphic display. Every summer brings some visiting yachtsman who comes into the harbor at high tide, finds the perfect anchorage in 12 feet of water and, failing to consider the 10-foot tidal drop, ends up aground at low tide. With our rocky bottom, this phenomenon provides good business for local boatyards but can be so easily avoided by consulting a good tide prediction program.
XTIDE AND TIDE TOOL
The first thing to understand is that, whether you are looking at data electronically or on paper, they are only predictions. Calculating tides and currents at a specific location at a given time involves a highly complex mathematical formula based on approximations and previous observations. While these predictions are often quite accurate, you still must be diligent and observe the conditions that surround you.
Reliable tide and current predictions can be found on the Internet or you can download a program that will run on your smartphone. We prefer tides to be calculated on the smartphone itself. When pulling into a remote anchorage, it's important that we are able to get a good tide estimate, and we don't want to be at a disadvantage because we couldn't get online. We are especially fond of the graphical applications that provide a quick visual reference for the tide height, as well as our current position in the cycle.
Fortunately, there are some excellent free tide and current prediction programs for Palm OS and Windows Mobile smartphones. There's a web-based solution that formats the information specifically for the Apple iPhone. For Blackberry and Symbian you will need to use one of the many tide and current prediction websites.
The most common software program for tide and current predictions is XTide, an open source tide prediction program that came out of the National Institute of Standards and Technology, and was written by Dave Flater. XTide was designed for Unix computers but has been translated to work on other operating systems. It has been around for more than 30 years. Thanks to XTide's freeware status, there are free tide and current programs available for many smartphones.
Our favorite, which we have used for years, is Tide Tool. Tide Tool is reliable, has a great user interface and works blazingly fast. There is support for nearly 7,000 stations worldwide, and the graphical display allows you to quickly see where you currently are in the tide cycle and to view future and past predictions. There is also an option to display the tidal predictions in table form.
The only drawback is that Tide Tool runs on Palm OS smartphones only. It requires Palm OS version 2.0 or later, which includes any Palm device that shipped after 1997. (To download a free version of Tide Tool for your Palm OS device, see link.)
ADDRESSING CURRENT
Note that for Tide Tool, as well as for other tide and current prediction programs, there are fewer locations for current prediction than the height of the tide. Tide and current predictions are dependent on data collected by NOAA. Unfortunately, funding for the National Current Observation Program has been dramatically cut since the 1980's.
However, you will find that current data does exist for critical locations such as busy canals and channels. For example, any good tide and current prediction program will have predictions for current in important passages such as Hell Gate in New York, Cape Cod Canal in Massachusetts and the C&D Canal in Maryland and Delaware.
