I have used Navionics as an app and on a chart plotter in northern Europe
for a couple of years and now the Med around Turkey
as well as some for some rivers and inland waterways in between.
Their app is easy to use and Navionics is constantly upgrading their products so my experience stand to be corrected but I found their charts to be wanting in several areas. The major deficiencies I experienced was in the detail they provided for small anchorages
. For instance in Norway
, you could many anchorages
with local boats in them but the Navionics charts showed only a dark blue area with no detail. The same was true for many passages between islands. There would be local markers but again just solid dark blue areas on their charts. With the number of rocks in those areas this became a major constraint.
In other areas such as the UK and the Netherlands
their charts were more complete. I also compared their charts to C-Map's and the detail was there if they had chosen to capture it.
I experienced similar or worse constraints on the Rhine and Danube. In this case open source charts filled in the gap.
Having said that however the app was easier to use than the C-Map
equivalent and their customer service
was top notch once I got to the right person.
You may want to have more than one app and related charts with you.