KVH Antenna
I have DishNetwork in my boat and it is hooked to a KVH tracking antenna that works at the dock and while sailing. Works fine all the time. If you want to go sailing and still have tv other than at the marina, you should get a tracking unit. Expensive set up, but works as advertised. You will need a pole designed for the antenna and then route your cables to an interface in the boat - mine's at the nav station. From there the antenna wires go to the dish box and then to the tv. You can now get HD as well as the normal older standard antennas.
Power it with a 110V to 12 volt regulator as it runs on 12vdc and power fluctuations take the programming out of the card in the antenna and require reprogramming by a tech. With the regulator, the voltage is constant and since installing this I have had no problems.
In heavy seas, the unit will break lock, but will generally reaquire it after a wihile.
Without my Dish and connection with Tennessee football, we wouldn't have as much sailing time as we do. I have been through 7 seasons with minor maintenance and would highlly recommend a system like this.
Raymarine makes a smaller anteanna and it may be just as good.