Japanese 1 The annoyance of "oo"

Is Shachoo spelled しゃちょお or しゃちょう? I was under the impression that if two "oo"s where present I'd have to put a う at the end but apparently that is not always the case.

>>5
No you can't, because しゃちょお and しゃちょう are romaji-ized in different ways, as shacho and shachou. At least for anyone who knows how to write romaji.