Video review of the incident revealed that the rudder shaft, though already broken, held together until the team went around the mark where it separated causing the race boat to abruptly leap into the air before slowing to a crawl, forcing the Americans to retire from racing.
SailGP's on-water Marine Mammal Observation team went back to the area and after an extensive search found no evidence that marine mammals were involved in the incident.
"Some things are just out of your control," said Spithill. "You can't control having a significant impact under the water. These things will happen."
The unfortunate result left fans in shock after a standout event from the US SailGP Team, who won two races and guaranteed their place in the final podium race before the end of qualifying.
Prior to the incident, the team had won the start of the three-team final race and extended its lead around the racecourse, averaging approximately 10kp/h faster than rivals Japan and Spain who also qualified for the Finals.