The Norton Point Beach opening has created river-like currents in Edgartown harbor, and with the 86th annual Edgartown Yacht Club regatta on this weekend, there will be plenty of sailors trying to negotiate the narrow opening between the Chappaquiddick ferry dock and Memorial Wharf which can challenge even the most experienced of sailors.

Trying to get in and out of the harbor is trickier since the breach in April 2007; it can be a spectator sport watching the smallest of sailboats get in trouble as they try to negotiate the opposing current.

Well practiced sailors, however, have found ways to make it in and out of the harbor with regularity.

Edgartown harbormaster Charlie Blair said small boat operators have opted to buy outboard motors. The channel currents can run upwards of five knots on a moon tide, he said, and he agreed this summer the currents are running less strong than a year ago.

Bill Roman, manager of the Edgartown Yacht Club, said: “If they hug the Chappy shore, they can usually slip in and out of the harbor without a problem.”

He said those who sail the Herreshoff 12 1/2 day sailboats seem to have mastered the passage. “Their boats are the most challenging to sail,” Mr. Roman said. “They are not as fast as the high performance sailboats. They have to be more particular about where they place their boats when they come and go.”

Warren Vose, 65, of Edgartown, has sailed Edgartown waters competitively since he was a boy. He has been sailing a Herreshoff 12 1/2 since 1986. He said the challenge of negotiating the harbor entrance is now a part of the sport.

“This adds another dimension to sailing in and out of the harbor. There are people sailing rivers all the time and they get used to it,” he said. “We have all gotten used to it,” he said.

“That summer that opening first came into being, that was all anybody talked about. Now it is getting to be old hat. The current seems less strong,” Mr. Vose said.

The prevailing advice is for boaters to pay attention especially to the wind and the current at the time they approach the opening. When all conditions seem to be working against the sailor, the word is to stay close to the Chappaquiddick side where the opposing current is less. Stay away from Memorial Wharf where the river is running fastest.

For those leaving the harbor, facing a strong current, the lighter current is at Chappaquiddick Point.

In the height of the summer, there are usually two Chappaquiddick ferries running. They crisscross the channel like a pair of closing scissors, so staying out of the way of an approaching ferry is rule number one.

Tom Dunlop, an avid Herreshoff sailor, offered a warning: don’t get too close to the ferry, even when it is at the slip.

The ferry can block the wind. On one reported occasion, the Chappy ferry was carrying a big truck. A passing sailboat got too close, lost its wind, lost its ability to steer, and the currents drove the small boat towards the ferry.

Crossing the channel just after the ferry has landed gives the sailor the most time.

Just past the ferry ramp on the Chappaquiddick side, an opportunity for calmer water appears.

Last year there was an eddy right next to the Chappaquiddick Point bathing beach, running in the opposite direction of the prevailing current, Mr. Blair said. This year there is a dispute about whether that eddy still remains. Mr. Blair believes it is gone. The waters are calm enough to give sailors relief.

For those sailors entering the harbor and facing the current, again there is less current on the Chappaquiddick side.

Sailors will find favorable currents running towards the harbor, just off from the Martha’s Vineyard Shellfish Group’s Chappaquiddick shellfish nursery. The building looks like a house; it is the closest to the Chappaquiddick ferry slip. There are a small group of spiles a few feet from shore, the shellfish group’s saltwater pump intake. Those spiles can be used as a mark for finding favorable water heading into the harbor when the current is opposing. Stay close to shore, tack close to shore.

The calmer side of Chappaquiddick is the place to do most of the tacking. Short tacks are far more advantageous than any attempt to tack in the fast moving channel. Any advances made near the shore can be lost in less than a minute if the sailor ventures into the opposing faster current.

Mr. Blair said the opening at Norton Point already is showing evidence of closing, just as it has opened and closed through the centuries: “The water near the opening is already shallow. It is moving east towards Chappaquiddick.”