I want to back up my chart plotter which uses Navionics (which, by the way, I have found surprisingly accurate). Most people I have talked to have an iPad (3G, GPS) and have the Navionics App which it is said works well. Clearly there are other devices on the market; i know Android also has a Navionics App.

Does anyone have knowledge enough to compare and contrast the two? Which should I buy?

I have the Navionics app on my android mobile but have never used the iPad/iPhone so I cannot compare the two. I love it.

Initially I had great difficulty downloading the Navionics app for the UK and Holland (which by the way is where the Ireland charts are) for my HTC even after having easily downloaded the Europe version before that. They have now fixed the problem. The apps cost about €25 each for European charts and less for US. I really didn 't want Europe but didn 't realize at the time that it did not include Ireland. The higher pricing in different regions is due to Admiralty royalties.

It works amazingly well even in our remote area on the west coast of Ireland. The community layer which is crowd source info must be fantastic for more populous areas.

Interestingly, I just went to the Google Play shop to see what was new and found that the apps I downloaded are no longer available. They seem to have been replaced with HD versions which cost €60+ and have terrible reviews.

Vice Commodore, OCC 

David,
The accuracy of the GPS on the iPad is excellent and it works perfectly well below deck too without an external antenna. Several different navigation apps can be used on the iPad. I have tried Imray 's and Memory Map but prefer Navionics. It is at least as accurate as our Raymarine / Navionics plotter and has the additional advantage that the charts themselves are more up to date and allow access to the community layer where users upload their own nav informartion to share with others. I have no experience of Android but assume that the Apps Run just as well.
Simon

I too had the initial Navionics application on my ipod touch to see what it was like. However I baulked at the cost of $60 coupled with poor reviews when my nearest and dearest gave me an iPad for my birthday.

We have multiple levels of redundancy for navigation.

Raymarine chart plotter at the helm with Navionics.
Macbook Air running Polar view coupled to the independent GPS in our AIS
PC Laptop with OPENCPN (free) if the Macbook goes down.
We have our Android phones with gps and applications that will give us a readout of position and now, our iPad with position and compass course, speed and the like as well.

But, I hear you say, what about the charts. We take a printout of the appropriate electronic charts at appropriate scales for our route from the PC before we go.

There 's an interesting article in CW about a new set of charts (electronic and paper) created by NV that has more detail than NOAA charts for the US. They also have detailed charts for CUBA. http://www.cruisingworld.com/blogs/nv-charts-the-paper-digital-sweet-spot

Of particular interest is the note below the article indicating that these charts are available for direct download on Xtraverse.com for iNavX for iPad and Fugawi for PC. Does anyone have experience with NV Charts?

Vice Commodore, OCC