I phone and navionics map app.

I read alot of post about this app running the battery down quickly in the IPhone. I am still in the dark ages (no Iphone). Can't use run the Iphone off a 12volt charger in your \
boat and not worry about the battery.

yes you can if your boat has a 12v accessory plug. Read where if you turn the gps function off after you get the lake location narrowed down then it helps on the battery life but haven't tried it. If you don't have gps on the boat, its a great app.

I have that app on my iPad and it is sweet... Battery on iPad is a lot better than the phone I would imagine. The price is right compared to the nav cards also.
BC