Thanks for comments. Mobile Navionics seams like a very competitive solution, the pricing is incredible, i don't get it how it can be so cheap compared to "normal" versions. A Friend is using it in a IPad, works brilliant except for bright sunlight( but how often is that a problem....)
Think will test the Chinese miracle phone as my track record for mobile phones in open boats is not that good , rather destroy a cheap one than an IPhone