There are loads of English words that don't have a vowel in them! they include rhythm, wry, sly, sky, fly, cry, sync (accepted as short form of "synchronise" & its' derivatives), all very good words to know when playing Scrabble! As you can see, not ALL English words have vowels in, sometimes a "y" pretends to be one...
Have you read the rest of this thread? In all the words you list, "y" is a vowel. The vowel is what distinguishes the pronunciation of "sky" from "skee" or "ska" or "skoo". Just try to pronounce the "sk" without a vowel.
The letter Y can be regarded as both a vowel and a consonant. In terms of sound, a vowel is 'a speech sound which is produced by comparatively open configuration of the vocal tract, with vibration of the vocal cords but without audible friction