As the Twitter account of Archimedes III put it late Wednesday, “The countdown is on!’’

The cruisers set sail Friday afternoon in the 111th Chicago Yacht Race to Mackinac. The majority of the fleet are in the divisions that begin racing in intervals at 11 a.m. Saturday east of Navy Pier. The first finishers should arrive late Sunday at Mackinac Island, Michigan, after 289 nautical miles.

The near-record water levels on Lake Michigan will have limited impact.

After two brutal weather years for the Mac, the field is smaller this year with 270 boats and about 2,200 sailors. In 2017, nearly a third of the field withdrew because of the weather. Last year, Chicagoan Jon Santarelli went overboard on Imedi shortly after the start and drowned when his PFD did not operate. That led to significant changes in safety procedures for the Mac.

This year should be different with a weather forecast along Lake Michigan looking benign and perhaps even setting the stage for a slow Mac.

Westrec Marinas’ executive vice president Scott Stevenson emailed that in Chicago, the high levels should not impact the handling of the boats before the race.

Jay Kehoe, director of CYC On the Water, said his only concern would be a “crazy surge or seiche’’ within the harbors. He said adjustments were made to the docks at Mackinac Island.

The higher water will not alter the course or open up any new areas to racing.

“I think because of the all rains, we will be watching river inputs and currents. Currents can get very strong,’’ said Sarah Renz, chair of the CYC Race to Mackinac. “There’s a lot of junk in the water.’’

The changes to safety procedures include requiring 50 percent of each crew to take the US Sailing Offshore Safety at Sea Course. There were five life-jacket classes on such topics as inflating and unpacking PFDs. About 90 people attended a two-day enhanced International Offshore Safety at Sea course.

Some boats of note for this Mac are Perry Fortune and Ryan Farrell’s Express 27 Air Force, Peter Thornton’s 105-foot Whitehawk and James Lidbury’s C&C 110 Zen from the Royal Hong Kong Yacht Club.

New to this Mac is the Point Betsie Team Race Challenge Trophy sponsored by the Storm Trysail Club. That friendly competition, which includes teams of three boats from three different divisions, has 22 teams entered.