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Author Topic:   Hand-held GPS Receiver and Plotter for Marine use
padrefigure posted 08-25-2015 07:23 PM ET (US)   Profile for padrefigure   Send Email to padrefigure  
Does anyone have a suggestion for a hand held GPS for marine use? We are contemplating dragging the Whaler 13 to the Keys in a few weeks and I would rather outfit with a hand held GPS, personal locator beacon, and VHF Marine Band radio to conserve space. I do not have a battery in the boat. I will order the Standard Horizon [HX870 hand held radio] discussed in an earlier thread, but I am looking for recommendations on the GPS and chart plotter. My preference for GPS-chartplotter would be Garmin since all of my other GPS units are Garmin, but I could be persuaded to consider something else.

Thanks .

cleep1700 posted 08-25-2015 08:00 PM ET (US)     Profile for cleep1700  Send Email to cleep1700     
The old Garmin 450 is what I use. It has been upgraded into the 650, but it is pretty much the same. Use lithium batteries; it sucks the juice out of alkalines quickly and rechargeables don't cut it.--Craig in windy Kansas
MarcB posted 08-26-2015 06:59 AM ET (US)     Profile for MarcB  Send Email to MarcB     
I have been using my iPhone 5S with Navionics for two years, I use it in on inland lakes and waterways, and it does perform quite well.

I have put mine in a waterproof case and has survived rain but no overboard trips yet.

One downside is screen brightness on very sunny days and battery life as well, I have a 12-volt USB adapter on the Newport so [operating time on the internal battery is not a limitation] for me. There are several articles on the web that show you how to maximize battery life by dissabling other internal antennas that are not required for positioning.

I think the annual cost to use Navionics is around $50 and includes auto-routing and other features. I am quite sure that they still offer a 7 day trial period as well. Make sure to perform the map downloads at home before heading out.

Even if the screen goes into sleep mode the app is still tracking via GPS and your recording your tail. Turn off the [navigation] app if not required; it will prolong battery life. For a short trip [use of an iPhone as a GPS receiver and chart plotter] could be a viable option.

Marc

jimh posted 08-26-2015 08:40 AM ET (US)     Profile for jimh  Send Email to jimh     
The mobile devices like an recent model iPhone typically contain a GNSS receiver that is more capable than many of the GPS-only receivers found in chart plotters that are dedicated marine electronic devices. The newer Apple iPhone devices usually have GNSS receivers that can receive GLONASS signals in addition to just GPS signals.

I think many people are confused about the capability of the GNSS receiver in a mobile device like an iPhone, and they incorrectly think that the GNSS receiver only works or only works well when connected to a cellular telephone network. This is a misconception. The GNSS receivers in mobile devices with cellular telephone capabilities are often Assisted GPS or A-GPS devices. That means the GPS receiver can acquire a position fix in less time than an unassisted GPS receiver could. The assistance is from the cellular data network. The cellular data network provides a very high-speed data delivery of the GPS navigation message, which otherwise must be received from the satellite constellation at an agonizingly slow data rate of 50-bits-per-second. Receiving the navigation message from the satellites can take a GPS receiver as long as 12-minutes, but receiving it via the cellular data network may only take a few seconds.

An Assisted-GPS or A-GPS receiver can still compute its own position based on the timing of the arrival of the satellite signals, but this process can be greatly speeded up if the A-GPS receiver can get the navigation message via cellular data networks. If an A-GPS receiver is out of range of the cellular data network, it can function just like an unassisted GPS receiver, and get the message (slowly) from the GPS satellites.

By using A-GPS, an Assisted-GPS receiver can obtain a valid position solution in just a few seconds, whereas a non-Assisted-GPS receiver might need a much longer time, perhaps more than 12-minutes, to get its first position solution.

I think many people operate under a misconception that mobile devices only employ some sort of triangulation of terrestrial radio signals from their cellular providers towers to determine their position. That might be happening, too, in some cases, but devices with an A-GPS can get a position solution from the GPS satellites in a very short time. For more information, see the excellent Wikipedia article on A-GPS receivers.

I have an old iPhone-3 device, and it has a GPS receiver. I don't have any cellular service for this device, and I often use it without any sort of WiFi connection. The GPS receiver in the iPhone-3 is able to compute a position solution that is within the usual accuracy of a GPS receiver--about a 30-foot circle of uncertainty--without any cellular or WiFi connection. I am certain that more modern iPhone devices would work similarly.

Some really modern GPS receivers in these mobile devices can obtain a position solution from a warm-start in a matter of seconds. To prolong battery life in the mobile device, the GPS receiver is switched off and then restarted a few seconds later to get a position solution.

jimh posted 08-26-2015 08:56 AM ET (US)     Profile for jimh  Send Email to jimh     
I am very much surprised by the low cost of electronic navigation charts for mobile devices, such as the Navionics charts mentioned above. I guess the chart publishers are counting on the huge number of possible customers owning mobile devices to make up in volume for the lower prices of the charts. You can often get a set of charts for a mobile device for $10 that would cost you at least ten times that much for a dedicated chart plotter.
dfmcintyre posted 08-26-2015 03:26 PM ET (US)     Profile for dfmcintyre  Send Email to dfmcintyre     
I've been using the Marine US app on an iPad Mini for two years now. Happy with it. Waterproof case, too.

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