Here is my list of the top Marine charting apps on the market. I have reviewed them all for you on i-Marine Apps to help you find the features you need.
They all offer some sort of charting function. Some are very basic and others offer data integration from your ships onboard navigation instruments through WiFi. Some use raster charts and some use vector charts. 
Find one that fits your price range and start navigating.
1. iNavX $49.99 for iPhone and iPad app, raster charts, vector charts require additional purchase, x-Traverse chart store, satellite and map views, instrument data integration, waypoints, routes, tracking, TCP/IP WiFi NMEA data, AIS, tides, points of interest, Google search, Theyr weather, GRIB weather, measuring feature, real time tracking, navigate to waypoint and route, auto pilot control, import/export routes and waypoints.
2. SEAiq USA $9.99 version uses USA NOAA charts, $39.99 for Open version, one week free trial, iPhone and iPad, Waypoint, Routes, NMEA data, AIS, free NOAA vector and quilted raster charts, Inland Waterways(USCE), Track recording, Active Captain POI, GRIB weather downloads, bearing and range, GPS sharing, navigate to waypoint and route, anchor alarm, instrument data, TCP/IP WiFi NEMA data, Aye Tides, import/export waypoints and routes.
3. Navionics Mobile $9.99 iPhone, $54.99 iPad HD, Auto-routing additional $4.99, Advanced Map Options additional $4.99, Navionics Plus additional $24.99, Nav Module additional $4.99, Navionics charts, waypoints, routes, tracking, sonar charts, markers, community layer, lakes, rivers, winds, tides, magazine articles, Google and Bing overlays.
4. SeaNav/NavLink US $19.99, NOAA Vector Chart free updates for 1 year. Satellite overays, Routes, Tracks, Waypoints, Weather, Tides, AIS, instruments, NMEA through WiFi, celestial data, augmented reality, range and bearing tool, search and export. 
5. Transas iSailor $4.99 -$24.99 per chart set, Nice digital vector charts, routes,waypoints, track recording, real time tracking, navigate to feature, NMEA GPS,Wind, Sounder and Autopilot through WiFi from $8.99 to $9.99 each, AIS display additional $9.99, import and export. Recently updated new user interface.
6. SeaPilot Free, $13.99 for Import/Export, Routes and Marks, NMEA. Additional purchases for charts, weather and AIS. Real time tracking, weather, instruments, AIS, waypoints, marks, NMEA 0183 through WiFi. Nice features with many in app purchase options.
7. Garmin BlueChart Mobile $Free, Charts $29.99 to $69.99 for vector charts, ActiveCaptain POI, search, routes, waypoints, GRIB weather conditions, dew points, temperatures, wind direction and speed, water temp, wave heights and period, celestial data, measuring feature, realtime tracking.
8. Nobeltec Time Zero $Free app, Charts $39-$49, quilted NOAA raster charts, no vector charts, satellite view, 3D view, range and bearing, SOG, COG, instrument display, GPS tracking, waypoints, routes.
9. NavPlay 4.99 for app, $39.99 for charts, $45.99 for yearly subscription. JeppesenVector charts, Chart table planning feature, weather, extensive instrument package, real time navigation, autopilot control, routing, waypoints, tracks, Alarms, web cloud, experience maker, logbook, NMEA WiFI. A lot of nice features but spendy.10. Jeppesen Plan2Nav Free, iPad, iPhone, charts regions $19-$37, C-Maps charts, GRIB weather, measuring feature, routes, waypoints, anchor alarm, tracking, tides, photos
11. FlytoMaps All in one GPS $8.99 iPhone, $18.99 HD for iPhone and iPad, search, tracks, measure, wapoints.
12. Marine Map Navigator $9.99 iPhone and iPad, display and tracking on NOAA vector charts, waypoints, routes, tides, AIS
13. EarthNC Marine Charts $19.99 iPhone and iPad, NOAA charts with overlays, weather, tides and POI.
14. Imray Marine Chart Navigator $41.99 realtime navigation with famous Imray charts.
