On Saturday, I tested mine out. The speedo is accurate up to around 45 to almost 50, then it goes my way
I will be testing the Garmin against the Tom Tom next weekend. As of now, the best GPS I have in my boat is the iPhone, with a $9.95 Navionics East app in it. I can see everything better, including the marker buoys, than with the Garmin 440. Interestingly, I have the optional $200 card in the Garmin.