By Tom Stieghorst

Billy Joel made headlines recently with the news that he’s going to play a monthly concert at New York’s Madison Square Garden for the foreseeable future. Joel’s gig starts Jan. 27. The first four shows are sold out, and prices for a May concert range from $64.50 to $124.50.

The development got me thinking about all the great piano entertainers I’ve seen on cruise ships this year. To my surprise, the piano bar has become a must-visit venue as I check out a ship’s entertainment.

There’s a tendency to reduce cruise entertainment to the main theater offering, because that’s where the cruise lines put on their biggest show and spend the most money.

Last week Royal Caribbean International announced it would license the Broadway musical “Mamma Mia!” featuring the music of ’70s pop group ABBA, which will undoubtedly be popular. But there are a number of secondary venues at sea, and they can be overlooked, especially on bigger ships. The piano bar is one of them.

On ships this year, I’ve been thoroughly entertained by solo piano acts in Crooners, on the Royal Princess, in the Piano Bar on the Oosterdam and in Piano Bar 88 on the Carnival Sunshine.

These entertainers were every bit the equal of top players in Las Vegas or London, and in some cases they are one and the same. I’ve also seen a few performers that lacked the energy, the audience rapport or the spontaneity of the best acts, at least on the night I saw them.

One of the things that makes a piano bar such fun is the intimacy of the room and the chance to get to know some of your fellow passengers, with music providing the introductions. On a seven-night cruise with a good piano bar, once word gets out it can be tough to find a seat.

James Barr, a piano entertainer from New York I caught on a recent sailing on the Vision of the Seas, said the audience makes or breaks a piano bar, and the No. 1 job for a good piano entertainer is to cultivate interaction from the audience.

“The more you talk to them, the more they have the nerve to get involved,” Barr said.

London-born, Barr is a self-taught musician who has been playing piano since he was 7. Now 37, he has been playing on ships for 12 years and on Royal Caribbean for nearly a decade.

He honors plenty of requests for “Piano Man” but also likes to mix it up. “Playing things people wouldn’t necessarily expect, like Jay-Z, adds to the energy,” he said.

Many people, I suppose myself included, stereotype piano bars as a lounge for washed-up showbiz types. Agents should prod their clients, especially younger ones, to rethink that assumption. On at least some of the ships I’ve been on, there’s no better place to be entertained.