Waterford - With a purple striped towel for a landing pad, a Ziploc food container protecting the engine and four palm-sized propellers spinning, the vehicle variously called a small unmanned aerial system (SUAS), a quadricopter - or simply a drone - flew over a nearly deserted Waterford Town Beach Thursday on a timely environmental mission.

"I'm using this to document shoreline change," said Joel Stocker, owner and operator of the 2-pound craft, fixed with a 14-pixel point-and-shoot camera programmed to photograph the beach at points on a grid set up to match GIS coordinates. "I've done a lot of stuff at Harkness Park and Griswold Point (in Old Lyme). If it's off season, I'll go to any beach I can find."

Stocker, assistant extension educator at the University of Connecticut's Middlesex County Extension Center and a former commercial pilot, started flying a model airplane drone about four years ago, then switched to the quadricopter about two years ago, motivated by scientific curiosity and a tinkerer's enthusiasm for making practical use of a new kind of gadget.

With sea level rise and more frequent severe storms accelerating the pace of change along the state's coastline, Stocker realized that a series of aerial photos from small drones, stitched together and laid over existing aerial maps, would show exactly how the shoreline was being altered.

"I share the information with towns and the state," he said. "I do this because I want to, not because I have to do this for my job."

At Waterford beach, a short distance from his home, he directed the drone to point the camera at the section overwashed during Superstorm Sandy in 2012 and since repaired by the town. For one of the few drone projects he has done as part of his job - which required UConn to obtain Federal Aviation Administration authorization - he took aerial photos of Great Gull Island, a nature preserve in Long Island Sound, and matched them to an aerial image to map the vegetation and reveal the extent of erosion at one end of the important bird-nesting area.

Stocker said he's very sensitive about not arousing any concerns about his drones, staying away from beaches when too many people are around. And he's careful to keep the quadricopter within the range where he can adjust its movements at any time and stay within FAA regulations. That means flying under 200 feet - even though the FAA allows him to go up to 400 feet - and not out of eyeshot.

"Legally, I can't fly it beyond unaided sight," he said. "And the FAA requires I have to have control of it at all times."

He built the drone himself, using a kit he modified and the help of friend and fellow drone user Don LeRoi of Old Lyme. He has taken it apart and put it back together several times, he said. It carries an 11.1-volt lithium polymer battery and wireless transmission equipment that receives information on the intended flight path he programs into his laptop. A typical flight lasts 10 to 15 minutes before the battery needs recharging.

"I used to fly real airplanes, and this makes me more nervous, because you put so much into making it," he said.

As he flew the drone at Waterford beach, it was easy to understand why this would be a valuable tool for environmental monitoring. The soft purr of the engine wasn't loud enough to scare most wildlife, and it could be set up in remote locations in a few minutes. For the Thursday outing, he carried all his equipment in a couple of backpacks.

"OK, now I should be able to fly it," he said, as he finished inputting the commands on his laptop. "It's going to fly right in front of us, then down the beach and back. Here we go."

The propellers whirled it over a stretch of dunes before it turned and headed back.

"Now, this is going to be our selfie," Stocker said, as the drone passed overhead, snapping a photo.

j.benson@theday.com