Updated

A certificate of inspection for the Missouri tourist boat that sank last month, killing 17 people, shows that it was on the lake at a time when the wind speed far exceeded allowable limits.

The Coast Guard on Wednesday announced it has convened a formal Marine Board of Investigation into the accident involving a Ride the Ducks of Branson boat. The vessel sank July 19 at Table Rock Lake.

The lake was calm when the excursion began, but weather turned violent and the boat sank within minutes.

The Coast Guard's certificate of inspection issued in 2017 prohibited the boat from being on water if winds exceed 35 mph or wave height exceeds 2 feet.

Investigators said the wind speed at the time of the accident was more than 70 mph.