as to the Lowrance products I don't have any experience owning one, (it's on the list) but I have sold a lot and installed quite a few I can say that every single person who has bought one loves it. *The internal antenna is fine in most cases on an open boat. *If you have a fabric T-top you will get slightly less coverage if you have it under a hard top you will even less, I have installed both kinds on most boats, some take a little longer than others to aquire enough birds to do any good. I highly reccomend NOT buying online...print the web page, take it to West Marine, they will price match and give you very good follow on customer support (returns and such)