WINDHAM — A tinkerer from Westbrook ended up in jail Monday when his plan to work on a homemade boat turned into a weapons-of-mass-destruction alert for emergency responders.

Joshua Prokey, 30, an electrician, was driving north on River Road at 9:40 a.m., set to work on the project he’s been dabbling with for nearly five years. He planned to go to a friend’s home and add more than a dozen 120-gallon propane tanks onto his pontoon boat, for flotation.

By Monday afternoon, he was in the Cumberland County Jail — not for anything to do with terrorism. Turns out one of his tanks — the one he was using to power his modified van — was stolen, police said.

River Road was closed for more than four hours after Prokey was pulled over, and traffic was detoured around the area.

Prokey was stopped just north of Alweber Road. A driver behind him had called police to report that a propane tank fell off the trailer that Prokey was hauling with his van.

Fire officials said later that no tanks ever did fall off the trailer. What police said they did find was 13 of the tanks, welded together on the trailer. Prokey’s van, hand-painted black and with darkened windows, contained another tank.

“What’s that van look like to you?” Windham Deputy Fire Chief David Nichols asked the media assembled a few hundred yards from the scene. “We’re ready for bad things to happen.

“When we pull into something like this, the first thing that comes to mind is WMD (weapons of mass destruction) — post-9/11,” Nichols said. “We have to think of the worst and have all our safeguards and precautions in place.”

Officials said later that Prokey was very cooperative, but they couldn’t take chances with the potentially explosive tanks.

Firefighters from Windham and Gorham and members of the Presumpscot Valley Hazardous Materials Response Team set up nearby, and members of the Maine State Police commercial vehicle enforcement unit joined Windham police to investigate.

Prokey’s friend Daniel Tucker said Prokey was planning to put the tanks on the boat he has been building for years, off and on.

“This was parked in front of my house last night,” Tucker said of the trailer loaded with tanks.

Tucker said that several years ago, he and Prokey ran the watercraft down a stretch of the Saco River, from Lovewell Pond to the Hiram Bridge.

Prokey later added walls and a roof to what had been a large raft supported by 55-gallon drums, Tucker said. With the extra weight, the boat needed more buoyancy, he said, hence the propane tanks.

He said he heard about Monday’s incident and went to check on his friend on River Road, but couldn’t get to him because Prokey was in custody.

Prokey may be handy, and creative in a way that some Mainers would admire, but he’s not good about following rules, said state Trooper Charles Granger of the commercial vehicle enforcement unit.

“You name it, he violated it — just about every hazardous-materials violation we have,” Granger said of Prokey’s trailer load of fuel tanks. “It’s not safe at all. That’s why we have regulations and why we have companies haul hazardous materials, not (private) people.”

Granger said Prokey didn’t have the required licenses or display the required placards identifying the materials he was hauling, among other violations. “We could have had a catastrophic incident over here,” Granger said.

Most of the tanks had some propane in them, said Windham Deputy Fire Chief John Wescott. There was an odor of propane, but no unsafe readings on firefighters’ meters. Just in case, the Cumberland County Emergency Management Agency developed a response plan that included a model of where fumes would spread if the propane tanks started to leak.

Emergency personnel at the scene asked nearby residents to stay in their homes until the situation was declared safe, Nichols said.

Shortly before 3 p.m., workers with Shaw Brothers Construction of Gorham used a boom truck to hoist the trailer onto a flatbed, which was then driven to a gravel pit in Gorham.

Wescott said the remaining propane would be burned off under the direction of the safety team for Downeast Energy, the natural-gas utility.

Prokey was charged with theft by receiving stolen property for possessing a stolen propane tank worth $400, said Windham police Lt. David DeGruchy. He was released on bail later in the day.

Tucker said he spoke about the incident with Prokey, who thought the authorities “blew it out of proportion.”

He said he and Prokey had emptied the propane tanks and welded them closed, so they were safe. He said his friend is very intelligent and just wanted to put the finishing touches on his boat.

Staff Writer David Hench can be contacted at 791-6327 or at: [email protected]

Correction: This story was revised at 1:22 p.m., April 4, 2012, to correctly name the company whose safety team supervised the burning off of remaining propane. it was Downeast Energy, the natural gas utility.