A kid just moved to Florida(?) gets a job as a delivery boy. He meets a cranky old sailor who runs a marina. The sailor doesn’t trust the boy until after he sets off a siren to scare off vandals at the marina. The sailor tells him sea stories and shows him a lump of ambergris. Possibly a mystery. 1950’s/60’s era YA book
A comment to add some info: I think the boy was recovering from some illness or sickly and at first was overwhelmed with all the bike riding his job required. There may have been a hill or bridge that was his nemesis. He’d replaced a local boy who was becoming a delinquent and suffered retaliation for taking the job. The delinquent was possibly one of the vandals scared off from the marina. It was an older library book that I read in the late 70s.
Not sure how helpful this will be, but when I read your description it sounded pretty familiar. I don’t have a title or author, but I thought it was set in Maine rather than Florida. Just a thought. 🙂
I read that one too! I think it was called The Secret (or maybe Mystery?) of Mound Key. I think I actually have it at home, so I’ll check. If it’s not that one, it may be another by the same author.
After YEARS of looking, I’ve identified this book. Finally! It’s The Secret of Willow Coulee, by Louise Bower and Ethel Tigue.