I have the iPhone version of Navionics
on both my iPad and my iPhone.
I have the component video cables
that I use all the time to watch videos, netflix etc. on a regular tv from both the iPad and iPhone.
I just tried to display the navionics
app on the tv and it doesn't work. I have looked at the settings in the Navionics app and there doesn't appear to be any setting to turn external video on.
My understanding is the software
developer has to write the code to use the external video (video out) features of the iOS. Unless the iPad version of the app has video or someone else has cracked the code, I don't think the iPhone/iPad Navionics app will drive an external monitor
The iPad is a good solution for the boat but I find myself using the iPhone almost all the time. It's nice to have it "in hand" when I am on on the boat.