I even pulled out my smart phone and tried out my Sailing Tactician App. This app has been fun to play with. How accurate it is I'm not really sure. It said I my max speed was 6 knots? Seems high. Is 6 knots possible in a CD Typhoon? Regardless the app is free and if you have a good smart phone one that uses satellites instead of cell towers it seems like a good toy to have for near coast sailing. The app has a slick interface and many bells and whistles on it I'm sure I'll never use but it serves the functions of telling you about how fast you are going. One should be aware the app pull on your phones battery pretty heavily so I would not recommend it for long term navigation but it works great for a couple hour day sail.