A 56-year-old South San Francisco man whose body was found at the Oyster Point Marina on Thursday morning is believed to have accidentally drowned, police said.

The San Mateo County coroner's office on Friday identified the man as William Kahn. An exact cause of death is still pending.

South San Francisco police spokeswoman Sgt. Joni Lee said Kahn is believed to have gone out to his sailboat, which was docked at its slip at the marina, alone on Wednesday night.

Kahn apparently tripped on a rope and stumbled into the water, then got his foot caught on the rope and was unable to pull himself up, Lee said.

Another boat owner spotted Kahn's body at about 11:30 a.m. Thursday.