Israel Horovitz is a celebrated playwright, a dramatist so prolific that when you ask him what his total of plays will be once Gloucester Blue gets its world premiere at the Theatre at Arts Garage on Friday, he replies, “ Gloucester Blue is number 70-something. A lot of them are short plays. But I need to write.”

That drive has produced such plays as the Obie Award-winning The Indian Wants the Bronx , Park Your Car in Harvard Yard, The Widow’s Blind Date and Line, which has been running at New York’s 13th Street Repertory Company since 1974, an Off-Off-Broadway record.

He is also a screenwriter, director, cofounder of Massachusetts’ Gloucester Stage Company, founder and artistic director of the New York Playwrights Lab, and father to five talented children, including Beastie Boys singer Adam Horovitz and Moneyball producer Rachael Horovitz. When the dynamic Horovitz turned 70 in 2009, that milestone was celebrated with productions or readings of his plays by companies around the world.

So it might seem surprising that in recent weeks, you could find Horovitz on the second floor of a Delray Beach landscaping company in borrowed rehearsal space, watching and working as director Louis Tyrrell and actors David Michael Sirois, Stephen G. Anthony, Andrea Conte and Michael St. Pierre worked on bringing Gloucester Blue to life.

“I’m here only because of Lou, period,” Horovitz says of Tyrrell, artistic director of the intimate 150-seat Theatre at Arts Garage. “Lou has been working with nothing but new plays for 25 years.”

Tyrrell did that work at Florida Stage, a much larger and nationally recognized theater that became mired in debt before it abruptly shut down in June 2011. Among the company’s long string of successful, critically praised productions was the 2010 staging of Horovitz’s Sins of the Mother, directed by the playwright. The writer and the artistic director became friends, and when Tyrrell got back into the game last year with the Theatre at Arts Garage, the first playwright the new company celebrated in its Master Playwright Series was Horovitz.

“Working on a new play is the thing I love to do most. What could be better than doing an Israel Horovitz play with the master in the room?” Tyrrell says.

Gloucester Blue, another of Horovitz’s many plays set in his adopted Massachusetts hometown, takes place in an abandoned fish processing plant purchased by a wealthy couple who plan to use it as a summer house. Painters Stumpy (Sirois) and Lathan (Anthony) are hard at work renovating the place, rushing to meet the deadline set by the owners, a guy nicknamed Bummy (St. Pierre) and his hot wife Lexi (Conte). Changing economic times, secret sex and murder figure into the plot of a play that is quite funny and stylistically adventurous.

Music, written by Adam Horovitz, figures into the plot as underscoring for certain emotional moments. Horovitz has experimented with ways to make the device work, in workshop readings at Off Broadway’s Cherry Lane Theatre and at the Arts Garage, and now feels that the music “...takes it to another level of truth. How many times do you feel an emotion that you cover up?”

Tyrrell, who notes that music in a play can be jolting, says he has worked to find “that fine line balancing honesty of emotion and humor ... There’s a level of comedy that says, stylistically, this is not naturalism.”

Conte, who has wanted to work on a full production of a new play with Tyrrell for years, was thrilled to have that first collaboration be on a Horovitz world premiere.

“I told Mr. Horovitz what an honor it was to be working with him. He said, ‘Get over it,’ ” she says, laughing. “The process has been great, especially when he comes up with gems he randomly pulls from the sky. He inserted a Robert Frost poem which exactly [captures] what my character goes through from start to finish.”

Sirois, whose play Brothers Beckett will get a high-profile production at the Arsht Center’s Carnival Studio Theater in Miami March 7-24, has been observing how Horovitz works during rehearsals.

“Selfishly, this informs me for working on my next play,” the actor-playwright says. “Sometimes, you’ll ask a question and Israel will say, ‘I don’t know. I don’t know yet.’ ”

However Gloucester Blue turns out, whatever its future, Horovitz says he has enjoyed collaborating with Tyrrell on it, and that he’s happy it will premiere at the Theatre at Arts Garage.

“I’m a do-good-work-and-they’ll-find-it guy,” he says, smiling. “I think it’s important to bring people into close contact with characters they’d cross the street to avoid in life. You just need tricks to pull them into your world.”