Ford vs Chevy discussion.... And I'm not going there!
Get the biggest screen you can afford with an eye to future purchases & upgrades. Meaning your first graph purchase should be made with the intention to network with your future graph purchase. A little forthought now in this regards will sure help down the road. If this means that for the time being you may have to move the unit between bow & console or just turn it to face forward until you have the funds to purchase another one, then so be it.
What kind of TM do you currently have and any plans to upgrade in the future? In regards to mounting transducers both on your TM & stern - spend the $$ and go here: http://www.transducershieldandsaver.com/home/ don't order online - call them.
There'll be a number of people, me included, at SCF that you can see our set ups & pick our brains.
As to brain picking, Piscolli warned me that if any of you guys give me a piece of your minds you are liable to come up short so I'll take it easy-lol jk
The boat is a 97 Sunbird 170 Fish and ski. This boat, trailer, and Motor/Trolling Motor were all produced by OMC as a package. So the boat has a 155hp Johnson outboard and a Johnson trolling motor. I haven't checked out the specs or model numbers on it yet but is has a small two bladed prop, ther head unit does not turn, just a red circle on top turns. Probably underpowered but i'm going with it for now since I have no electronics on the boat.
I figure there is a trolling motor in my future and I want the ability to link with gps to stay on station without anchors when that time comes. So yes I want to buy a GPS system that is compatable with that technology. For that reason I was thinking Humminbbird but I think I like the Lowrance graphics and ease of use better.
I'm not sure whether Lowrance has units capable of this feature but I'm guessing in the next couple years it will be available on most brands. (imagine a future where your boat takes you to the spot, finds the fish, deploys fishing outriggers and line to the correct depth, then uses algorhythms to land the fish based on species, weight, and string tension. A stern deployed netting drone then nets the fish and flys it to the shore based auto cleaning station that filets , bags, and flash freezes the filets or batters and cooks them in time for your dinner back at camp. Hell why not just party and camp and let your boat fish for you?? I love the future, everything is so much easier there.)