Ichy is right. I won't leave the dock without knowing that both of my radios are working and without a couple sets of backup batteries for the handheld in case other navs go down. These tools happened to have saved my life and a couple of friends of mine a few years ago when my powerboat decided to breakdown ten miles off Tatoosh with fog rolling in and no power to steer us off of the waves beating us from the sides as we were taking on more and more water. If I did not have the radio I coud not have made the mayday call, without the gps to give proper coordinates, it would have the taken the Coast Gaurd a much longer time to find us in the fog, in the open sea (possibly without the boat drifting with our lifevests beyond the recoverable stage of hypothermia). But as it were, we communicated coordinates pretty frequently while everyone bailed like madmen and the CG pulled right up to starbaord bow with about 150-200 foot visibility. Accidents happen at sea that you sometimes have no control of. Be prepared and don't become a statistic.