This is one of (very few) Carolyn Haywood books I absolutely do not remember reading as a kid. For its time, it was nice that it was doing its part to dispel prejudice against "gypsies". The story is a low-key mystery (who stole the sailboat! surely it must be those gypsies! oops we were jerks, no it wasn't!)
Content note: Some of the kids in the book do use the word "gyppo" when talking about Robert's Romany friend, Aaron. Aaron only uses "Romanies" to refer to himself and his people, whereas everyone else uses "Gypsy". I would have been super happy if Robert had begun to say "Romany" himself, but I guess that was asking too much? Eh.
This is not my favourite Haywood book at all, even aside from the slurs. It's just somehow lacking, and I can't really lay a finger on why.