Authorities coming off a record-setting year for tragedies on the Potomac River say there is little mystery to why people are dying in high numbers.

"Boaters who do not wear personal floatation devices are much more likely to die," says Col. Robert K. Ziegler, Superintendent of the Maryland Natural Resources Police.

Deeply concerned, authorities from the NRP, US Coast Guard and National Park Service gathered on the eve of the Fourth of July holiday weekend to draw attention to the problem.

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There were 21 boating deaths in Maryland in 2017, which was a grim record. Seventeen of the deaths occurred on the Potomac River and its tributaries, including the sinking of a sport fishing boat in November that killed three men.

Fourteen of the boaters who died on the Potomac in 2017 were not wearing a personal flotation device.

"It doesn't work if you don't wear it," said Julie Brown, the Boating Education Coordinator for the Maryland NRP.

Brown demonstrated in a pool how it is nearly impossible to put on most styles of PFDs while struggling in the water after an accident.

"You're in a panic after you have just gone in the water," Brown said.

The boating industry has responded to boater complaints that many PFDs are too bulky, hot and uncomfortable to use in summer weather by introducing lightweight devices that automatically inflate when the wearer falls in the water.