out Navimatics Charts
& Tides. That has iPad support today with full native resolution.
Charts & Tides is currently the only iPhone or iPad app that rotates the charts as your boat turns too. This is an incredibly important feature. Why go backwards in time when the charts couldn't rotate? Charts that don't rotate are what you get with iNavX, Navionics, and Memory-Map. This should be seriously considered before spending $50 on software
for your iPhone. You'll surely end up hating the forced north-up/chart-up display especially when you're on your boat and moving through the water
. Most of the apps don't have a demo/trial mode so you won't find this out until you've bought it.