If you have an iPhone, you can download the iNavX Marine application ($50; www.inavx.net). iNavX downloads NOAA RNC raster U.S. waters marine charts, which can be manipulated with your phone's touchscreen. Theoretically, you can use the phone's location services-GPS on the latest generation, cell tower triangulation on older models-to plot your course on the charts in real time as well as to store and navigate to waypoints. I downloaded the program and found that it can be painfully slow and sometimes defaults back to your current position, rather than where you want to go. In no way should it replace your chartplotter or even your handheld GPS, but having an iPhone as a backup isn't a bad idea. You can also use it to plot your trip beforehand. At the very least, it gives you instant access to "paper" charts that fit in your pocket.
Time and Tide
I love the iPhone application called Tides, from Mobile Geographics (free; www.mobilegeographics.com). It provides tide and current information for more than 7,000 locations. Once updated with your present location, it provides times for that day's high and low tides, as well as sunrise and sunset. You can scroll through to find out tides for future boating dates, too. Switch to the current feature and it'll give you slack ebb and flood times as well as the moon phase. For anyone who fishes or boats in tricky skinny water areas, it's a fantastic tool.
I have several Internet weather services that I check before heading out on the water. I now have them bookmarked in my iPhone's Safari browser so I can access them when I'm on the water, too. They're not foolproof, but they helped me avoid that sudden storm during my Block Island cruise. Here are a few of my favorite sites:
Weatherunderground - This provides updated satellite weather imagery as well as access to local marine forecasts.
NOAA Weather - NOAA's graphic interface allows for one-touch marine forecasts anywhere in the country, with the conditions and extended forecasts based on collection from weather buoys. Be warned, though, that it's not always up-to-date, as noted in NOAA's disclaimer.
Fishweather - Get wind observations and forecasts, weather reports, tides and currents, and even sea surface temperature readings for your home region.
NOAA Wave Models - A graphic, updating chart that uses color coding to show estimated wave height and arrows to show direction. Scroll down to Forecast Zones and select your region, the type of information you wish to view, and the frequency of the image loop. Note, too, the disclaimer that the predicted conditions aren't always the most current.