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

"Different ships, different long splice", I guess. My experience is very different, anyway. However, I see any type of chartplotter as not being the principal means of navigation until you get up to the full-on ECDIS big ship nav systems, with built in redundancy and backup. Until you get to that stage, paper chart and GPS is the principal means, and a chartplotter is a great means of adding another layer of information, even if it 's not 100% reliable. Even the big ships carry paper charts.

Anyway, back to the iPad. I 've just sailed up through the tropics, Tahiti to Hawai 'i. I kept the iPad running all the way, plugged into the 12v socket. I read some novels in iBooks, listened to some music. No problems with keeping it charged. I don 't need to keep it out in bright sunlight. If I need to see it from the helm, I put it on the companionway step. If there 's any moisture about, I put it in a Ziploc bag, and have found no problem with the touchscreen. The screen is much, much better for daylight viewing than my Macbook, and Ive given up on OpenCPN and the like for navigation.

No, the iPad is great for those times when you actually need a chartplotter for info in real time, such as entering a strange port at night, and weaving between hidden dangers when the visibility is poor and landmarks not abundant. Other than that, when you 're offshore, what need of a chartplotter? Only, as far as I can see, to avoid having to buy and carry a shipload of detailed inshore charts. For my trip through the Kenai Peninsula and Prince William Sound this summer, I 've got 1:200,000 paper charts, and will happily be using the iPad, and Transas iSailor and Garmin BlueChart, when the vis is poor, and when I 'm exploring the nooks and crannies.