The Ethan Allen was in violation of state law during its sightseeing cruise on Sunday, officials have told ABC News.
New York regulations say that any commercial boat carrying between 21 and 50 passengers must have one crew member, in addition to the boat's operator. According to officials, that applied to the Ethan Allen and its 47 passengers. The tour boat capsized on Lake George on Sunday, killing 20 people.
"Under the license for the vessel, they are required to have a crew member in addition to the operator for 21 to 48 passengers," said Wendy Gibson, spokeswoman for New York's Office of Parks, Recreation and Historic Preservation. The operator was the only crew member aboard during the cruise.
"If that's the case, there's going to be a problem, and it looks like that's the direction this is headed in," Warren County Sheriff Larry Cleveland said.
State regulators have suspended licenses for all five vessels belonging to Shoreline Cruises, the company that operated the tour, officials told The Associated Press.
Experts say extra crew can be critical in an emergency. "To direct people to where to find life jackets, to help them put the life jackets on, if they had to leave the vessel, how to get off the vessel safely, yeah, very important," said retired U.S. Coast Guard Commander David Smith.
State officials said the boat's captain had a valid master's license issued by the state and that the boat was inspected in May and passed.
A key question is whether the state did a stability test on the Ethan Allen before the boat was licensed to test how far the boat would list or lean if weight shifted to one side.
U.S. passenger ships -- including everything from sightseeing boats to fishing charters to ferries -- carry 200 million passengers a year. Commercial shipping is considered a relatively safe industry.
Last year, there were 757 boating deaths, most from recreational boating -- just 17 were commercial passengers.
Those killed are often not wearing life jackets. The Coast Guard says 85 percent of those who drown in boating accidents would have survived if they'd been wearing life jackets.
The Passenger Vessel Association is in early talks with the Coast Guard about revisiting life jacket regulations.
ABC News' Lisa Stark contributed to this report.