MIAMI (Reuters) - The 12 Cubans who tried to sail a 1951 Chevy truck from the communist-ruled island to the United States got no marks from U.S. authorities for their creativity.

The would-be emigrants were sent back home.

Since Fidel Castro's 1959 revolution, Cubans have tried to leave the Caribbean island on rudimentary rafts, on giant truck inner tubes, in stolen boats and planes, even by windsurfer.

But no one remembers anyone attempting the 90-mile crossing of the Florida Straits in a floating flatbed truck with 55-gallon (250-litre) drums strapped to its sides, tires still in place, a propeller attached to its drive shaft and a driver behind the wheel.

"We've seen surfboards, pieces of Styrofoam, bathtubs, refrigerators. But never an automobile," Coast Guard Petty Officer Ryan Doss said on Thursday.

A U.S. government plane spotted the bright-green truck chugging through the water at 8 mph (13 kph) on July 16 about 40 miles south of Key West, just over halfway from Cuba to Florida. The Cubans had fashioned a makeshift, bright yellow shelter on the truck's bed.

"The truck's engine was actually running, propelling it through the water," Doss said.

The Coast Guard picked up the 12 Cubans from the vintage vehicle and took them back to the island on Sunday.

The truck was deemed a hazard to navigation and was sent to the bottom.

Under the U.S. immigration policy known as "wet foot, dry foot," Cubans who manage to set foot on U.S. soil are usually allowed to stay while those stopped at sea are routinely sent back to Cuba.