Boating Tips


Posted 8/6/2012

Are Your Electronic Navigational Charts Up to Date?

From their inception, electronic navigational devices capable of providing accurate positional information on a real-time basis have proven to be a major benefit to military and commercial vessels. The earliest was Loran (Long-Range navigation system), which relied on a chain of shore-based radio towers that transmitted signals on predetermined frequencies at specific time intervals. The first iteration of Loran, called Loran A, required a huge onboard receiver unit and an engineering degree to operate. The Loran A only had a modest degree of accuracy, so very few ever made their way onto recreational boats. That model was followed by an improved system designated Loran C, which incorporated microprocessors and provided an easier way to determine position. It proved to be amazingly accurate.  

The onboard Loran C receiver would lock onto signals from two radio towers in different locations, and calculate the time delay from transmission to reception in microseconds. The time delays would provide the distance of the boat from each of the towers, and the unit would display two sets of numbers, called TDs. The TDs corresponded to a Loran Grid overlaid on a standard paper navigational chart. To determine your exact position, you had to record the numbers, go to the chart, find the gridlines that corresponded to the numbers, and locate where they intersected. The point of intersection was called a waypoint. It was a tedious process, but the rapidly shrinking size of the Loran receivers caught on with recreational boaters who navigated away from their home waters. In addition, fishermen loved it because they could now save the location of their fishing spots in TD logbooks, and return to the exact position with unerring repeatability. 

As Loran C navigational electronics became more sophisticated and smaller, the earliest chart plotters came on the scene. They displayed a crude navigational chart on an LCD screen along with an icon representation of the boat that would move across the chart in sync with the boat’s movements. The system was capable of saving a library of waypoints, and showing them graphically on the chart. 

Just as the initial Loran-based plotters were making their appearance in recreational boating, along came the introduction of the Global Positioning System (GPS). GPS does not rely on shore-based radio towers. Instead it receives signals from multiple satellites in geosynchronous (stationary) orbit. Today, GPS chart plotters are available for any size recreational boat to fit any budget. They have revolutionized navigation and dramatically enhanced boating safety, but a plotter is only as accurate as the electronic charts it displays.  

Paul Michele is the national sales manager for Navionics,® the industry leader in electronic navigational charts. He is also an avid boater and fisherman who understands the importance of having the best and most current charting software in your onboard plotter.

“Far too many boaters consider electronic navigational charts as little more than an afterthought,” Michele said in a recent discussion. “They buy a chart plotter, and rely on whatever imbedded background chart came with the unit. Or they spend the money on far more advanced charting software, but fail to update it periodically so it remains current and accurate.”

The overwhelming number of chart plotters available to boaters in the U.S. are capable of running Navionics® software, considered to be the gold standard in electronic charts. Actually, it might be more accurate to say they are the platinum standard because the company’s top of the line charts for marine and inland lake use are the Platinum+ series. 

“The data used to create and update Navionics® charts comes from a variety of sources including the government, both military and civilian branches, private sources, user-generated and our own proprietary soundings,” Paul said. “In the case of our freshwater lake charts, a good deal of the soundings data is from our own sources.”

Navionics® Platinum+ multi-dimensional marine charts take the navigational experience to a whole new level with 3D view, integrated aerial imagery layering, and port photos that can overlay the already superior base chart to offer the boater perspectives well beyond that available from traditional charts. The aerial imagery provides extremely accurate representations of land masses and shallow water bottom contours on lakes and in bays, rivers, inlets and nearshore coastal waters that enhance boating safety, and can be a great tool for fishermen, too. The user can customize the on-screen appearance and types of data available for viewing to meet any navigational need. 

“One of the issues Navionics® has addressed recently is how best to provide the most current chart data, even to users who purchased their charts months or years ago,” Michele continued. “Bays, rivers, channels and nearshore ocean bottom features can change over time as a result of dredging or natural erosion. Major storms can quickly impart significant changes almost overnight. For this reason electronic charts can be out of date and fail to accurately represent current conditions.

Navionics’® answer was to develop a new feature for their electronic charts called Freshest Data. Freshest Data provides daily updates online along with the new Navionics® PC App, and is available free with newly purchased Navionics® Platinum+ charts. There is a modest fee for the service for charts purchased after June 2010. If your chart was produced before June 2010, you need to replace it to take advantage of the service. Freshest Data includes things like buoy changes, sand bars shifts, newly discovered rocks, submerged structures and more. These chart updates and improvements average more than 1000 every day and they are easy to download and install on your onboard plotter, ensuring you have the most current charts available for your boating safety. 

Freshest Data also includes a revolution in digital charts called the Community Layer. This feature consists of hundreds of thousands of edits made by Navionics® users, like you, that are viewable on Navionics® mobile app, PC app and select chart plotters. There are also navigational charting apps for SmartPhones, allowing you to essentially carry your plotter in your pocket. 

GPS chart plotters are one of the best ways to enhance your boating experience and are a major aid to safe navigation, but without accurate, up-to-date navigational charts, their benefits degrade with time. If yours are more than a few years old, it’s time to purchase new ones and advanced customer services like Navionics® Freshest Data will keep them accurate for years to come.