From what I learned, in old English, the "u" was represented by a "v" character (think about the letter "A" in older text where it doesn't have the horizontal line in the middle), so when spelling something that needed a "wh" they would put "uu" which at the time would've looked like "vv."
If you really wanna mess with your head, in Espanol, the letters "B" and "V" can be pronounced the same.