I have the Vexilar SonarPhone. T-BOX $149.95 version. I use my iPad for sonar display as well as my smart phone in wrist band that came with the unit, all works well even in sunlight. I added a couple 12v lighter outlets to my boat for USB chargers so everything stays charged. You can have up to 256 (WiFi limit) smart phones looking at your sonar as the same time so everyone in the boat has access view to sonar. (although if you have 256 people in your boat, you overloaded) I also bought the DigiLand 7" Tablet $40 where I put the Navionics Boating app. The two are linked together via WiFi in the T-Box. Great sonar detail and goes to a depth to 240ft. When running jointly the sonar will map the contours of a lake as you travel on the lake. It has tracking, waypoint, and sharing with other users along with other features.
Very pleased with the way this set-up works.