The List
There are 176 5 letter words with Y as the first letter. The highest scoring is YUKKY at 19 points in Scrabble. 5 carry three or more vowels, which makes them useful for dumping a vowel-clogged rack.
YAARSYABASYABBAYABBYYACCAYACHTYACKAYACKSYAFFSYAGERYAGISYAHOOYAIRDYAKKAYAKOWYALESYAMENYAMPYYAMUNYANGSYANKSYAPOKYAPONYAPPSYAPPYYARCOYARDSYARERYARFAYARKSYARNSYARRSYARTAYARTOYATESYAUDSYAULDYAUPSYAWEDYAWEYYAWLSYAWNSYAWNYYAWPSYBOREYCLADYCLEDYCONDYDRADYDREDYEADSYEAHSYEALMYEANSYEARDYEARNYEARSYEASTYECCHYECHSYECHYYEDESYEEDSYEGGSYELKSYELLSYELMSYELPSYELTSYENTAYENTEYERBAYERDSYERKSYESESYESKSYESTSYESTYYETISYETTSYEUKSYEUKYYEVENYEVESYEWENYEXEDYEXESYFEREYIELDYIKEDYIKESYILLSYINCEYIPESYIPPYYIRDSYIRKSYIRRSYIRTHYITESYITIEYLEMSYLIKEYLKESYMOLTYMPESYOBBOYOCKSYODELYODHSYODLEYOGASYOGEEYOGHSYOGICYOGINYOGISYOICKYOJANYOKEDYOKELYOKERYOKESYOKULYOLKSYOLKYYOMIMYOMPSYONICYONISYONKSYOOFSYOOPSYORESYORKSYORPSYOUKSYOUNGYOURNYOURSYOURTYOUSEYOUTHYOWEDYOWESYOWIEYOWLSYRAPTYRENTYRIVDYRNEHYSAMEYTOSTYUANSYUCASYUCCAYUCCHYUCKOYUCKSYUCKYYUFTSYUGASYUKEDYUKESYUKKYYUKOSYULANYULESYUMMOYUMMYYUMPSYUPONYUPPYYURTAYURTSYUZUS