I read this in 1965 and was under the impression it was pretty contemporary. The story concerns a young teenage girl whose family spends summers somewhere on the Atlantic coast. This particular summer they have an older teenage girl board with them and she’s a bit rough around the edges but is kind and wants to improve he self and her circumstances. She has a buttery soft yellow leather jacket that the younger teen admires. The older teen gets into some sort of scrape and decides to move on as she believes it to be in everyone’s best interest. She quietly leaves behind the yellow jacket as a gift to her young friend. I remember the cover depicted ocean, pier, maybe an old house, and a bit of stormy weather. Suggestion: The Sea Gulls Woke Me by Mary Stoltz