Navionics on my iPhone 5 and iPad mini are my paper substitutes. I agree they are both handy and quite adequate for my meager needs. I'll look into this other app, thanks for the heads up.
Navionics has pretty maps, but watch out for their current tables. They were seriously off, as in 8 knots off, at Sechelt Narrows (aka Skookumchuck Rapids) when I was going through back in December. Ports and Passes hardcopy and OpenCPN on my PC were both correct, so Navionics got outvoted in my planning, which was a very good thing in this case.