Handheld wireless networking

Networking solutions always used to mean wires and fixed electronic boxes at the nav station or the helm. Now you can add wireless handheld devices that make networking a handheld accessory. Perfect examples of this are the Apple iPhone 3G equipped with iNavX (a full-function GPS chartplotter) or a Palm OS device running a chartplotter program called ActiveCaptain.

First we’ll look at Apple’s iPhone. Out of the box the iPhone provides Wi-Fi or cellular access to information from the National Weather Service real-time doppler weather radar. Its Safari web browser also accesses a host of other weather and information resources, including National Oceanic Atmospheric Association (NOAA) and U.S. Coast Guard sites, Notices to Mariners and the Physical Oceanographic Real-Time System (PORTS). After activating the iPhone we purchased the iNavX electronic charting application from the Apple iTunes online App Store ($49.99). Download and installation took only a couple of minutes.

As with the two other GPSNavX chartplotter programs (1. GPSNavX that uses NOAA raster navigational charts [RNC] and 2. MacENC that uses both electronic navigational charts [ENC] and RNCs) the iNavX is remarkably easy to use. A brief touch on the iNavX icon on the iPhone’s screen opens the application. After a few seconds the initial screen automatically displays the list of NOAA raster scan charts (RSC).

As soon as the iPhone has determined its location, the chart list shows a selection of the charts closest to the phone’s position, in chart scale order. We touched the line for chart 11415, Tampa Bay Entrance and confirmed our desire to download the chart on the subsequent screen. About 20 seconds later the chart was on the screen, centered on our position icon. After downloading, charts are stored in the iPhone’s memory which, depending on the amount of other stored information, can hold the charts for a very large area (the entire RNC library occupies less than 400 MB).

As with all chartplotters, the screen’s the thing. The iPhone’s 3.5 inch diagonal, 320 x 480 pixel, 160 bpi color screen is easy to see in every situation, including direct tropical sun. Screen brightness range, in the fully automatic, manual and night modes will cope with any condition you are likely to encounter.

Just as with the GPSNavX and MacENC chartplotter programs, learning to use the iNavX chartplotter is a simple process. The opening iNavX screen displays the initial selections; Charts, Waypoints and Instruments with a secondary field for access to the TCP/IP NMEA Client, Units choices and commands for removing local charts, removing tracks (the plotter will store 100 track points, recorded at a 0.1 nmi interval) and About iNavX which shows the software version in use. Touching the Setup icon at the top right of the chart screen opens the seven-item Chart Setup menu which provides toggle control switches for Position Icon Kept Visible, Position Icon Transparent, Velocity Vector, Night View, Show Waypoints, Show Tracks and Show AIS Targets (the latter function requires a separate AIS receiver, there are limits to what could be built into the phone). Once set, this menu will rarely demand attention.

Chartplotter functions are controlled via the five icons at the bottom of the screen, Chart, Info, Waypoints, Instruments and Tides (the latter requires purchase of AyeTides from the App store ($14.99). Alternatively you can download a free tide/current application, Tides or Tide Graph ($1.99) although AyeTides is easier to use since it is accessed directly within iNavX.

Chart management is a fingertip process. The chart is scrolled by sliding your finger across the display. Move the chart to a position partially or completely off the screen and it will be redrawn to display the new area in a couple of seconds. Chart zoom, from 5 perent to 100 percent, is controlled with a tap on the chart scale bar at the bottom of the screen. Waypoints can be created by entering latitude and longitude or with a touch on the New Waypoint box on the Waypoints screen. A single tap on an on-screen waypoint’s ID will highlight it, allowing the waypoint to be dragged to a new location. A double tap on the screen establishes a base point for measuring bearing and distance to a second point and to display its latitude and longitude.

The unit’s internal GPS receiver provides the primary position determination information. However, in the event GPS information is lost, the iPhone automatically reverts to determining position by triangulation based on cellphone tower locations. Data links to the outside world include Wi-Fi, 3G and EDGE cellular service in addition to its cellular voice telephone capability. (Don’t plan on using iNavX to plot your flight path when traveling on a commercial airline, switching the phone to the Airplane mode disables both GPS receiver and the Wi-Fi link. However, with the advent of in-flight cellular service, allowing cell phones to be on in flight, you will be equipped to back-up the pilot’s navigation).

The iNavX can communicate with an NMEA server to display instrument information and can work with the MacENC chartplotter program running on the laptop at the chart table.

There are few limits to what the iNavX program can do for the ease, speed and accuracy with which it performs its functions. The handheld iPhone chartplotter might be easier to use in rough water than the fixed mount unit at the helm. Put it in a buoyant waterproof case and it’s ready to accompany you anywhere. However, this iPhone-based chartplotter must be viewed in proper perspective. Its strong point and its primary limitation are identical: it is small, barely a handful. As the progressive increase in the size of computer, radar and chartplotter screens clearly show, people will choose the largest available screen. Keeping this in mind, an iNavX-equipped iPhone will be an unbeatable back-up navigation (and when in cell range, communication) device. It will shine most brightly when you take it with you in the dinghy or in a sea kayak and when you use the phone’s Web browser or cell phone channel to download the current weather radar image.

You can also make screen shots of the chart in use by simultaneously pressing the Home button at the bottom of the phone and the Sleep/Wake button on the top. The images will be stored in the phone’s Photo Album and can be downloaded to iPhoto or e-mailed from the phone using an application such as Palringo.

A Palm OS alternative

Load the ActiveCaptain software (www.activecaptain.com) and for less than $50 a Palm OS unit can become a valuable on-the-water navigation and information resource (versions compatible with other cellphones are in works). The system can access the entire NOAA RNC library and can store the entire set in a 4GB memory card. With an active Internet connection the program will provide a wealth of information about the area in which you are cruising, including details on anchorages and notes about phone numbers for services. Add a Bluetooth GPS and the Palm becomes an active chartplotter. Operation is based on a combination of screen taps, cursor key operations and the pull-down menus familiar to users of most Windows-based chartplotter programs. ActiveCaptain’s online tutorial is easy to follow and will assure a smooth transition to this version of in-your-hand chartplotter navigation.

We would be remiss in this brief summary of hand-held navigation devices if we failed to mention what we would like to see next; a head-up display option, a monocular, high-resolution, infinity focused imaging device that, worn like your glasses or clipped to the visor of your cap, would present an image of the navigation picture, superimposed on the visual scene. The technology for this advance in navigation information visualization exists and would enable the navigator to integrate what he sees with the charted information (plus radar and sonar information with the appropriate interface). Carried to its logical technical completion it would overlay synthetic vision on what the eye could see, with no need to look at a display screen.

By Ocean Navigator