I am interested in mobile navigation apps. I do not own a boat and when I rent one, I'd like to have some tool to locate myself on the water and keep me out of dangerous or shallow areas . At a minimum, it would show my position, Aids to Navigation, and charted water depth by using NOAA charts that are frequently updated. I am initially looking at free or inexpensive apps that have minimum or no cost associated with installing and updating charts.
After reading some comparisons online, I decided to try SEAiq USA for the iPad. It has many more features than my minimum requirements. It was easy to add NOAA charts that include the Potomac River and Chesapeake Bay. Using the app for about a week, it has already prompted me to get updates to the charts I have installed.
There is a free trial, and the cost to buy the iPad/iPhone version of SEAiq USA is only $4.95 which is intended for recreational use. Full details are available at http://www.seaiq.com. The least expensive option for Android devices is $49.
Other versions are available for Android, Mac and Windows computers and the pricing varies up to a $300 version intended for pilot use.
I have explored the app at home, but not on the water yet. The charts look very much like paper charts and it does take some practice zooming in and out to see the desired level of detail and the desired scale. After taking the Navigation class recently, it is quite interesting looking at the charts in this SEAiq USA app.
I will update this posting after using SEAiq while sailing.
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Update: In July 2018, I did use my iPad with SEAiq on a Wednesday evening social sail. It worked great. I could see our speed and course and the position was accurate as verified as we approached and passed navigational aids. The only problem I experienced is that an iPad is difficult to view on a clear sunny day. I have to use something to shade the screen because even with the highest brightness setting, the sun can be too bright for the iPad to usable.