Waterford — Leave it to a former English teacher to find the perfect words to describe how he knew it was time to retire.

“It seemed like a period at the end of the sentence, you know what I mean?” Donald Macrino said Tuesday.

Macrino, 62, the Waterford High School principal, said he plans to retire at the end of the 2012-13 school year next June. He agreed to stay on for his 17th year as principal to oversee the school’s transition to its new $67 million high school, which is slated to open next April.

A city councilman in New London, his native city, Macrino has enjoyed a long career in education and in 2008 was named state Principal of the Year by the Connecticut Association of Schools.

This fall he will enter his 40th year as an educator. He will have 20-year stints in both New London and Waterford.

“He is a person when you think about it who just completed his 39th year, and he still has the energy and dedication to approach whatever challenge comes his way,” Superintendent of Schools Jerome Belair said. “He’s been instrumental in this new construction of the high school. We’re very fortunate that we can have him here for an additional year.”

Macrino, a graduate of Eastern Connecticut State College, worked as an English teacher at New London High School and was later the dean of students. He took an assistant principal job in Waterford at Clark Lane Middle School and later became principal at the high school.

He said that in recent years students have come to rely on schools and teachers more because they have less outside support. That has created a need for teachers to be better prepared and trained, and Macrino praised his staff in Waterford for being just that.

He also said he found many opportunities to help children with problems “outside of grammar or literature” in his early days in New London. Becoming a principal presented further opportunities to do the same.

“When I became an administrator, I was dealing with that all the time. It was an opportunity to really contribute to the betterment of a young person’s life,” Macrino said.

An avid auto racing fan, Macrino said he plans to continue to spend a lot of time with his family in retirement. He and his wife, Pati, live within a mile of the couple’s three children.

While some future opportunities may also arise from being a member of the executive boards for the National Board for Secondary School Principals and the Connecticut Association of Schools, Macrino said with the new high school set to open he felt it was the right time to step aside.

“It’s sort of like when you’re in the line to get on that gigantic roller coaster. You’re not sure whether you should go through with it or not,” Macrino said. “But then you jump in the car and enjoy the ride. You try to find the most appropriate time to end one’s career and move on to the next stage.”

jeff.johnson@theday.com