Youth Club scored after 10 minutes through Scott Francis and Strath MacKenzie added another. Further first-half tries came from Jy Griffin (Alan Rutter converting) and Aaron McColm.
A stolen line-out led to Tynedale’s first try, making the half-time score 5-22.
Second-half Selkirk tries were scored by Fergus Hitchcock and McColm, Rutter converting the latter.
Tynedale adjusted their team and were rewarded with a further try.