vowel letters in English literally don't mean anything right, it's like any of <a, e, i, o, u> can be any of /a, e, i, o, u, ɑ, ɔ, æ, ɛ, ɪ, ʌ, ʊ, ə/, /ʉ/ if you're Australian, and you can just throw in a /:/ in there mostly at random.
which is how we get things like 'sweetie' -> 'sweaty'