The List
There are 173 7 letter words with Y as the first letter. The highest scoring is YUPPIFY at 20 points in Scrabble. 69 carry three or more vowels, which makes them useful for dumping a vowel-clogged rack.
YABBERSYABBIEDYABBIESYACHTEDYACHTERYACHTIEYACKERSYACKINGYAFFINGYAFFLESYAGGERSYAKHDANYAKKERSYAKKINGYAMALKAYAMMERSYAMPIESYAMULKAYANKEESYANKERSYANKIESYANKINGYANQUISYANTRASYAOURTSYAPOCKSYAPPERSYAPPIERYAPPIESYAPPINGYAPSTERYAQONASYARDAGEYARDANGYARDARMYARDERSYARDINGYARDMANYARDMENYARKINGYARNERSYARNINGYARPHASYARRANSYARROWSYASHMACYASHMAKYASMAKSYATAGANYATTERSYAUPERSYAUPINGYAUPONSYAUTIASYAWLINGYAWNERSYAWNIERYAWNINGYAWPERSYAWPINGYCLEEPEYCLEPEDYEADINGYEALDONYEALINGYEALMEDYEANINGYEARDEDYEARENDYEARNEDYEARNERYEASTEDYECHIERYEEDINGYEELINSYEGGMANYEGGMENYELLERSYELLINGYELLOCHYELLOWSYELLOWYYELMINGYELPERSYELPINGYEMMERSYENNINGYERDINGYERKINGYESHIVAYESKINGYESSINGYESTERNYETTIESYEUKIERYEUKINGYIBBLESYICKERSYIDAKISYIELDEDYIELDERYIKKERSYINDIESYIPPERSYIPPIESYIPPINGYIRDINGYIRKINGYIRRINGYMOLTENYNAMBUSYOBBERYYOBBISHYOBBISMYOBBOESYOCKINGYODELEDYODELERYODLERSYODLINGYOGHURTYOGINISYOGISMSYOGURTSYOHIMBEYOICKEDYOJANASYOKEREDYOKINGSYOKKINGYOLKIERYOMPINGYONDERSYONKERSYONNIESYORKERSYORKIESYORKINGYORLINGYORPINGYOUKINGYOUNGERYOUNGLYYOUNGTHYOUNKERYOUPONSYOUTHENYOUTHLYYOWLERSYOWLEYSYOWLINGYPERITEYPLIGHTYPSILONYSHENDSYSLAKEDYTTRIASYTTRIUMYUCKERSYUCKIERYUCKINGYUGARIEYUKATASYUKIESTYUKKIERYUKKINGYUMMIERYUMMIESYUMPIESYUMPINGYUPPIESYUPPIFYYUPSTER