It depends on how far you are. With the current system at least 1 Satellite needs to be close enough to a ground station. So that means from your boat up to the

It depends on how far you are. With the current system at least 1 Satellite needs to be close enough to a ground station. So that means from your boat up to the sky, and from there to land. It has also been suggested that at strategic locations you could have swimming ground stations in order to cover a pretty large area. Eventually however it will cover everything as the satellites will communicate directly between each other with lasers.