Updated Nov 2017


On the evening of 18 July, 1969, Senator Edward Kennedy said he drove off a low wood bridge on Chappaquiddick island in the town of Edgartown, Massachusetts. His vehicle sank in about 6½ feet of water. He managed to escape but his young female companion, Mary Jo Kopechne, drowned. Two days later, Armstrong and Aldrin landed on the moon, so the incident mostly faded from public view, at least here in Australia. However, many people in the USA were unhappy with Kennedy's subsequent explanation of how the accident occurred. There was no formal investigation, apart from an exhumation hearing and inquest, there was no autopsy, and there was no formal analysis of the accident itself.



Police Chief Arena sitting on Kennedy’s submerged car,

unaware that Mary Jo Kopechne is inside. A faint tire track

from Kennedy’s vehicle can be seen starting in the

middle of the bridge, heading to the right then ending just

before a small sheet of plywood butted up against the right rail.





The car after it was dragged from the water showing damage

to roof and windscreen, and scratch and scuff marks on the

rub rail at the edge of the bridge. Both passenger doors were

also deeply dented.




There were many unanswered questions. The general assumption is that Kennedy’s vehicle rotated through the air and landed partially on its roof and partially on its side on the water, blowing in the passenger-side windows and crushing the front windshield in the process. But if that had occurred, how was it possible that neither of the occupants had even the slightest scratch? Kennedy’s Oldsmobile was not equipped with seat belts.

Kennedy claimed he left a party at 11:15 P.M. to drive Mary Jo back to Edgartown but accidently turned right onto a narrow dirt road rather than continuing on a sign-posted paved road leading to the ferry. However, the car was seen at about 12:40 A.M. by an off duty deputy sheriff, driving down the dirt road, almost an hour after Kennedy said the accident had occurred.


Kennedy claimed he accidentally turned right

into the dirt road leading to Dike Bridge, even

though he intended to follow the paved

road to the ferry.



Kennedy said he was disoriented after the accident and ran back to the party to get help. He then said he swam across the ferry crossing to his hotel in Edgartown. Next morning, after "he fully realised what had happened," he reported the accident to the police. However, before he did he is alleged to have made a number of phone calls to attorneys and others. Most of the party goers were whisked off the island as quickly as possible without reporting to the police, who remained unaware of who might have been involved until several days later.

In the books listed below there are many theories. One is that Mary Jo was the driver. Another is that there was a second companion, and that Mary Jo was asleep on the rear seat when the accident occurred.

The incident raises some interesting physics questions. The vehicle fell about 6 feet off the bridge into the water and ended up about 20 feet from the point of departure. When found, it was lying on the bottom upside down. The roof was badly dented, the front windscreen was shattered and both passenger side doors were deeply dented. According to the diver, this damage occurred before the vehicle was extracted from the water. There was no other damage of any significance. The question is, could the water have caused all that damage? If not, what did? 

The police presented an accident sketch at the exhumation hearing, indicating that the left skid mark was 33 ft 2 in long and the right skid mark was 18 ft long, both starting at the start of the bridge and continuing straight to the edge, parallel to each other. However, the official inquest photo shown above does not appear to show two tracks – it appears to show just one which stops short before it reaches the rub rail. Moreover, the bridge was 10 ft 6 in wide. The tires on Kennedy’s Oldsmobile were 5 ft 3 in apart. It would be impossible to fit two parallel lines of those lengths and widths diagonally across the bridge. Therefore, either the police made a mistake, or the car was spinning and the two tire marks converged. There was no mention of converging skid marks at the inquest.

At an author’s request, I was asked to study the accident. The author, Bill Pinney, a former investigative reporter, had found a new witness whose testimony seemed to imply that the accident occurred in a far different fashion than most have previously supposed. My analysis has taken more than two years to complete. Along the way, a large quantity of previously unpublished photographs of the accident scene were uncovered which helped me determine how the accident must have occurred. Among other things, I have concluded that the accident scene diagrams drawn by the police chief and State accident inspector, presented at an exhumation hearing and subsequent inquest, appear to have been deliberately fudged. 

My analysis of the accident, with original photos and diagrams, can be found in Pinney's book, Chappaquiddick Speaks, now available at


The background to the book is described on YouTube at


Included in the book are simulations of the accident using model cars. The videos below show how the accident might have occurred. Two slow motion movies were taken of a toy vehicle pitching forward into a container of water. In one case, the vehicle hit the bottom of the container on its front end. In that case, the front of Kennedy's vehicle would have been badly damaged. There was no damage to the front end at all.


In the other case, the toy vehicle rotates rapidly in the water and lands on its roof. That would explain the damage to the roof and windscreen, and the absence of any damage to the front end, but how come the passenger doors were also dented? If the vehicle landed on the passenger doors, then how come the roof was dented? If the vehicle landed on its side and dented the doors then it would have sunk slowly to the bottom. There is some interesting physics in those questions, involving the way that the drag force acts on a rotating object, and the magnitude of the drag force.





At least a dozen books and 1000 articles have been written on the accident. None of them analyse the accident itself in terms of the physics. Here are the main book references:


     Don Hastings, The Ted Kennedy Episode, Reliable Press, 1969

     Jack Olsen, The Bridge at Chappaquiddick, Little, Brown & Co., 1970

     Zad Rust, Teddy Bare: The Last of the Kennedy Clan, Western Islands, 1971

     Robert B. Cutler, You, the Jury, self-published, 1973

     Malcolm Reynold, The Inspector's Opinion, Saturday Review Press, 1975

     Richard and Thomas Tedrow, Death at Chappaquiddick, Pelican Publishing Co., 1976

     Robert Sherrill, The Last Kennedy, Dial Press, 1976

     Larryann Willis, Chappaquiddick Decision, Better Books Publisher, 1980

     Leo Damore, Senatorial Privilege, Regnery Gateway, 1988

     Kenneth Kappel, Chappaquiddick Revealed, What Really Happened, Shapolsky Publishers, 1989

     James Lange and Katherine DeWitt, Chappaquiddick, the Real Story, St. Martin's Press, 1992

     Leslie Leland and J.B. Shaffer, Left to Die, Strategic Book Publishing, 2009

     Donald Nelson, Chappaquiddick Tragedy: Kennedy's Second Passenger Revealed, Pelican Publishing Co., 2016