Wonderful Yachting Regattawatches made in France: Yema Yachtingraf.
Made in the 60s. 7 different types, some types with different dials and cases or/and casebacks.
Not sure about the serial ranges, some stuff is not systematic.

But lets try to categorize them. Here you find a start. Next will come the serial overview. Please send me a pic from front and back of your Yachtingraf to help the research!