It increases the 3G/ WiFi internet coverage when you are in the harbour at anchor or navigating along the coast. WebBoat is more than a 3G/Wi-fi router, it's also an antenna and an access point. It provides a high speed internet connection both wireless and Ethernet throughout your boat. Just insert a SIM card into the external slot, and all internet devices on board (iPhone, iPad, smarphones, tablets, etc.) will connect to the network and use the internet. If a Wi-Fi network is present, the weBBoat will switch to it automatically avoiding 3G fees. Very easy installation, no wiring needed, only a 10/30volt cable to the antenna.