Many people are being woo 'ed by the cheap Navionics (and Garmin I believe) apps for iPhones and iPads. I have been experimenting with using an Ipad as my principal chart plotter and have concluded that the concept is a non-starter.

I have been cruising the east coast of South America over the last three years from top to bottom (and back). The C-Map coverage on my chart plotter for many of the places I have been to has been non-existent. The Navionics cartography was infinitely more comprehensive. So I decided to experiment with using an iPad in a waterproof housing as my principal chart plotter, using iNavX chart plotting software and downloading Navionics charts. I also have a Vesper XB8000 WiFi AIS transponder that streams AIS data as well as all the boat 's NMEA 0183 or 200 data to the chart. In theory this gives you almost everything a dedicated chart plotter provides, but for a fraction of the cost (and you have all the other functionality of the iPad to boot). However, I have found that it is unusable as a principal chart plotter because:

1.In bright sunlight, the chart can barely be seen
2.In hot climes, just at the point when you need it most, the screen blanks out with a message saying it is too hot, and cannot be rebooted for at least 10 minutes
3.When the screen gets wet from rain or spray, the touch screen doesn 't work - it has to be wiped dry every time you want to do anything like zoom in or out.
4.During the day, even when plugged in to a charger, the draw from the software and the brightest setting causes the battery to slowly drain.

Whilst the arrangement is great as a standby that you can use, for instance, at the helm when conning in or out of anchorages, it is sadly not fit for purpose as a principal chart plotter. So back to the drawing board and the cheque book!

Tim Barker, S/Y Mina2

I 'm in Prince William Sound, Alaska. I have the paper charts, but they 're difficult to read when I 'm exploring the minor channels and tiny coves where the US Coast Pilot says "not to be entered without local knowledge". The iPad is proving to be totally reliable, and I can zoom right in to see the detail that I can 't make out on the paper chart. However, one app is not enough. I have Garmin Bluechart and iSailor, and frequently have to compare one with the other, and choose the one which has the better detail. Though they 're both based on the NOAA charts, they do vary as to what they choose to include.