About 35 local boat owners and officials of the National Park Service crowded into the snack bar at Columbia Island Marina last Wednesday night to discuss the proposed closing of the median strip of the George Washington Memorial Parkway to prevent left-hand turns into the marina from northbound lanes.

The National Park Service has proposed the closing because of the high number of accidents at the site. During the last 17 months there have been 65 accidents at the intersection, involving 132 vehicles and resulting in 23 injuries, parkway police officer Allen Vandam said. The intersection ranks among the top 20 most dangerous on the parkway.

The Columbia Island Marina has about 300 parking spaces and 384 power boat slips. Sailboats dock at the marina on Daingerfield Island.

Closing the median strip would mean that northbound parkway traffic will take I-395 south to Boundary Channel Drive onto the parkway south to the marina entrance. Northbound traffic leaving the marina would have to turn south, then loop around the lagoon and merge onto the parkway north.

Margaret Osborne, assistant superintendent of the parkway, timed the new routes and said the changes would add 4 to 4 1/2 minutes to the drive into or out of the marina. She said that this might be offset by shorter waits at the intersection.

Most boat owners were not happy with the proposed median closing. "The inconvenience is not yet warranted until they try interim measures like blocking the intersection at peak accident times and enforcing the existing laws," said Dave Gerson, a resident of Crystal City and a law- yer with the Department of Labor.

Gerson, who keeps a 34-foot cabin cruiser at the marina, said he goes to his boat at least five days a week and believes the closed median "will be a personal inconvenience to me and my guests."

While the boat slip holders may be the most inconvenienced by the change, most of those entering the marina use other park facilities such as picnic tables. According to Vandam an average of 102 cars per hour use the entrance to the marina in the summer. This congestion combined with speeding on the parkway, poor visibility at the intersection and cars making illegal turns create the problem.

Several of the boat owners believe the move will only relocate the accidents. "Closing the median will just divide up the existing problem," said Gerson.

The proposed closing is part of a program for improving safety on the parkway. Officials said the marina intersection could be fixed with a minimum of cost and traffic disruption.

The Park Service is accepting comments until Aug. 17. Comments should be mailed to Superintendent, GWMP, c/o Turkey Run Park, McLean, Va. 22101.