Catawba (from what I know of it) is pretty vigorous and can easily take up a lot of trellis space. I would suggest atleast 8 feet or more to give ample room. Are you plating them on any kind of treillis system? In a single or multiple rows? Planting arrangement will likely depend on how many vines you are planting and how you want to farm them.
Probably a two wire trellis. I'm planting them in a test vinyard in my back yard. I'm planting 10 of them and 10 cabernet sauvignon. I already have 18 scuppernoogs that I planted last year I'm in north Alabama and I'm figuring out what will grow for me. --------------"There's many a slip twixt the cup and the lip."
I planted my Catawba's 8 ft. apart, but would do it at 10 ft. if I was doing it again here in No. Ga. Mtn's. [1550 ft. elev. E-W row on a 2 wire trellis] Growth is more vigorous that I though it would be. My Merlot is fine at 8 Ft. spacing. Roy