I crocheted this blanket a while ago for someone who just had a baby boy. I made up my own pattern and I think I can remember how I did it.
I used size 5.00 hook, With white/blue and dark blue/light blue cotton. First I made twenty granny squares out of the white/blue yarn, each had four rows. Then I went around the granny squares three times with the dark blue/light blue yarn. I then sewed the pieces together and went around the edges with shell stitch and i was done. It can go really quick if you work on it a lot, but thats not what I did and it took me a month.