Marc515,
Your information is a little sparse. If you want an app for a tablet or smartphone, they are usually dependent on internet access. That makes them a real bad choice for underway navigation.
If you are going to put a GPS puck on a laptop, Street Atlas or Streets and Trips would have done well for you, but both are out of print.
The remaining is Co-Pilot for RV which is a web-based app.
Sorry Guy, the boat you wanted sailed 3 years ago.
I am going to keep running SA-15 with a clearance over lay as long as I can.
Matt