Do I need a chartplotter

[Baggywrinkle]

I've gathered an impression that navigating by a smart phone (as I do) is seen by some as unseamanlike and gets scowled upon by some even though for the sort sailing I do it's proved effective and reliable. I'll eventually get round to fitting the chartplotter as it just seems right, but not sure why.

I use Navionics on my mobile devices too because it is extremely useful and easy to whizz round the charts and zoom in and out .... my plotter is a bit clunky in comparison. The reason why many scowl at navigators using mobile consumer devices is the positioning hardware which in most cases uses assisted GPS which tringulates cell-phone masts and uses GPS, Android devices also use WiFi information in a similar manner. This is not as good as WAAS found on plotters, and you don't necessarily know how accurate the position is, which makes it less than ideal for that one time when it gets a bad fix and plots you somewhere you are not.

From the Navionics website ....

Android platform

If your GPS position is not being displayed correctly, please make sure that your mobile device has an internal GPS receiver.
If it does not have an internal GPS receiver, you will not be able to determine your location outside of Wi-Fi range.

If you are using a device with an internal GPS receiver, please follow these instructions to resolve your issue:

1.Make sure that the Use GPS Satellites feature is selected in your Android phone’s Settings/Location & Security.
2.Make sure the phone is exposed to the sky and out of doors.
3.Give the phone enough time to locate a signal (sometimes minutes).
4.Re-Boot phone if a signal cannot be made.
5.Check against other apps using GPS, such as Google Maps, if they place you in the same position as Navionics Mobile.

If it is still not working after enabling GPS Satellites it is possible that it could be an issue with your device's internal GPS receiver, or a software issue with the Navionics mobile app. In order to determine the cause of the problem you can perform a test following the procedure below:

1.Go to the device’s “Settings” menu
2.Go to “Location” and disable “Use Wireless Networks”
3.Verify if the GPS is still working on the Google Maps App, and then using the Navionics app.

​These steps will vary depending on the device you are using. Some may require to turn Locating Method to GPS only or to use all available options (GPS, Wi-Fi and mobile networks) to determine your location.

This will determine whether or not it is the GPS that is not working correctly, or the Navionics mobile app.

http://navionics.force.com/kb/artic...-GPS-Technology/?q=gps&l=en_US&fs=Search&pn=1

I don't get the same advice from my Plotter manufacturer. My GPS antenna is mounted in a place where it has a 360° view of the sky. It also informs me how accurate the fix is and when the WAAS symbol appears (shortly after start-up) I can rely on it to a few metres but I still always cross-check by looking at relative positions of things on the chart, and then in the real world around me. I'll often put the cursor on an AIS taget, a buoy or some other landmark to get the magnetic bearing and then check it against my compass. If it all matches up I'm happy.

I wouldn't criticise anyone using mobile devices as long as they are fully aware of the limitations, and have a healthy dose of paranoia concerning their accuracy - not to mention a means of cross-checking. (charts, multiple devices, hand bearing compass etc.)

PS: This is a design constraint of mobile devices, the hardware needs to be very cheap, the GPS chips used are usually combined GPS, BT, WiFi chips and the antenna for GPS is usually packaged assuming usage in portrait mode for phones. Cases, location and orientation can affect antenna performance. As consumer devices will spend most of their life on land and indoors, the positioning requirements of the device manufacturers and the OS suppliers are optimised for this scenario and hence augment GPS with other wireless signals like Phone Masts and WiFi which go through buildings.