Three men have set off on what they hope will be a record-setting journey paddling down the Mississippi River.

Kevin Eckelkamp, Nate Lastinger and K.J. Millhone left the river's headwaters at Lake Itasca in Minnesota on Thursday in their canoe, bound for the Gulf of Mexico.

To break the current record of 18 days, four hours and 51 minutes, they'll have to average about 6 miles (9.7 kilometers) an hour, night and day.

Lastinger tells Minnesota Public Radio News that one crew member will sleep while the other two paddle five hours at a time, straight through.

"We might stop for an hour a day," he said. "Tops."

Lastinger and Eckelkamp are from St. Petersburg, Florida. They got the idea after Eckelkamp's uncle, Steve, died unexpectedly last summer. At the funeral service, he met Millhone and heard stories about how Millhone and Steve Eckelkamp set the record for fastest paddling down the Mississippi River in 1980. Back then, the two men took a little over 35 days to accomplish the trip of more than 2,300 miles (3,701 kilometers).

Eckelkamp was inspired and decided to try to break the Mississippi paddle record again. He talked Lastinger and Millhone into going with him.

"I want to continue the legacy," he said. "Maybe get the family name back on the record."

Millhone was reflective before the trip began. He said his old record has been broken twice, and the trio will need to cut his previous time in half.

"For us to get the record now," he said, "we're going to have to average between six and eight marathons a day, for 18 days in a row. When I did it the first time, I lost 25 pounds in 35 days."

On Thursday morning, the trio ate breakfast and then walked a half-mile from their campsite to Lake Itasca. They slid the boat into the water, and paddled away at 6 a.m. sharp — hoping to be in New Orleans before the month ends.