My wife found this book the other day in our personal library. She got it for a birthday present when she was about 14, because she wanted to learn how to sail. Looks like a DSII on the cover, and there's a DSI inside in the "Daysailer" section. My sail number is 847
Nice coincidence, since that's what we've ended up with.
The book is copyright 1964 and 1974.