GPS Reception Help

Getting GPS Sonar for my boat and want to get side imaging as this will be great feature. Hummingbird is the brand I want.
I want a unit with internal antenna for satelite positioning versus external antenna. Is external more effective? I have a tiller and boat platform is wide open so internal antenna unit will be wide open on deck of boat-no interference from boat side or windshield. Don’t want to have seperate antenna to mount and/or trip over when fishing or covering boat. I can’t find the bigger Hummingbird units with internal antennas and that makes me think external is better and should be used if I’m forking over the big bucks for a wide screen unit. The 798 ci si is only unit I can find with internal antenna, but I really want th wider screen.

I’ve got the 798 Ci SI with the internal GPS and it works great. No problems with getting a fix. Only complaint is that the word/numbers are super small on the screen but compared to paying for the big screen, I’m very happy.

Thanks Codger for the input but as you say screen and data could be bigger. Gettin older and bigger is better.