cjamesb wrote:Actually its in Latin that Jehovah starts with an I. The Hebrew Tetragrammaton doesn't use vowels.
In Hebrew, the "I/J" in Jehovah is actually a yud, which is a consonant. Other yuds at the start of Biblical names include Yoseph (Joseph), Yehoshuah (Joshua), and Yerushalayim (Jerusalem).
The reason it became "J" is that the "J" used to give a "y" sound. When the sound changed, the transliterations remained.