gps

Since this is on a pontoon and mostly only inland lakes and sometimes out the pier to lake Michigan, the need for Navionics cartography isn't really necessary, is it? I know I want down imaging. But would the additional map from Navionics really benefit me?

I have a 2011 2275 RCW that came with a Garmin 95 Fish Finder.  It is installed in the dash as noted in the photo.  I would like to replace it with a GPS unit that will fit into the same space.  Does anyone have any experience doing this?  Can you suggest a GPS unit that will fit into this same...

the 2002 207L I bought has a Garmin 300C-on it which seller is incIuding which give me depth and fish Fishing . I want a Marine gps to go with it to provide general gps info including bottom contours but don't necessarily want to junk the 300C for a combo unit. Any thoughts?