I didn't have it stretched even in these photos, but even so:
Close up of the stripes and the stitches:
You're gonna need 12 ounces of three colors of yarn (or 36 ounces of one color, I guess, or 18 ounces of two colors -- depends on how you want to do the striping). My advice is to buy those Caron One Pound skiens. This is what I used:
Caron One Pound in Sky Blue
Caron One Pound in Azure
Caron One Pound in Cape Cod Blue
Chain 136. This is so simple. Work 6 sc rows of one color, 6 sc rows of another color, and 6 sc rows of your third color. This makes one set of stripes. I made eight sets of stripes for a 51x63 inch blanket. It's big.