Lowrance has a unit called the XOG. It gives both verbal "road" directions and can accept Lowrance or navionics chips for boat use. Cabelas has them on sale for $149. Only downside is that the battery life is only about two hours, but as long as you have a cigarette lighter on you boat, no problem. I did alot of research before I bought mine, and this was the only one that did everything I wanted.