Checklists, weather, required safety equipment, nav lights, buoys & beacons, float plan, boating tips from Discover Boating Canada
GPS locator, get speed & heading (GPS), check & report weather, tide predictions, call for service.
SailDroid (GPS free)
Provides compass, speed, position, and distance log.
Regatta Race Tracker
Uses the service of InstaMapper.com, a device "locator", to follow several sailboats in a regatta live. Each boat has a cell phone that sends GPS locations using the app “GPS Tracker” (Android, iPhone and Blackberry).
BC Racer (GPS)
Beer Can Racer provides navigation data for racing, including a tack indicator, location marker, sailing angle, bearing to target, distance to target, and speed. (Android Market only)
The Weather Network
Weather current, hourly and 5-day forecasts, satellite, radar, trends
Android app that displays the locations of 35,000 U.S. boating ramps.
Google Earth, Google Ocean
Google Earth displays maps anywhere in the world. Google Ocean displays points of interest under the ocean.
Maps and Charts
Maps and Charts are perhaps the most essential (and one of the most amazing) uses of the iPhone for yachting especially if you're bareboating. These programs pack amazing features into the iPhone.
Navionics Nautical Charts
Available for U.S. East Marine, Mediterranean, etc.
iNavX Marine Navigation
U.S. marine charts for West Coast, Gulf Coast, East Coast, Great Lakes, Alaska, Hawaii, Virgin Islands.
iPhone app displays tides and currents in ports worldwide.
Apple live weather reports
The Captain's Toolbox
Navigation and seamanship resource in one easy to use application.
(no connection required)
The Practical Encyclopedia of Boating (~$20)
500 topics on boat maintenance, navigation, boat handling, knots, boat design, nautical reference data.