Best navigation app for android table

[Adethefridge]

Who's the front runners when it comes to navigation app's these days ?
I already have Navionics installed on my ipad and although I'm happy with it I'm looking for a second system to install on an android tablet as a backup / alternative.
I'm reluctant to shell out on a duplicate app so looking for some advise as to a alternative to Navionics.
The area I need charts for is Southern Portugal and the Med.

 

[gjgm]

Who's the front runners when it comes to navigation app's these days ?
I already have Navionics installed on my ipad and although I'm happy with it I'm looking for a second system to install on an android tablet as a backup / alternative.
I'm reluctant to shell out on a duplicate app so looking for some advise as to a alternative to Navionics.
The area I need charts for is Southern Portugal and the Med.

Garmin don't seem to make anything for Android, and MXMariner don't have charts for Portugal.
Why do you want something as well as Navionics , though (I think it by far the best anyway)?