SAND ISLAND — In the middle of Casco Bay, between the picturesque cottages that line the shores of Chebeague and Cliff islands, an American flag rises from a sliver of land where the radio, tuned to Coast 93.1, was blasting from inside a vine-covered hut out onto a beach dotted with weathered picnic tables, plastic chairs and pairs of shoes.

Closer to the water, a horseshoe crab shell hangs from a sign with the rules of the island: take what you bring, stay off the sand dune, no digging holes.

Protecting this half-acre spot, just 8 feet above sea level, is one thing Scott Kern is serious about, but a lot of the time, he leans toward silly, his gray beard belying a youthful enthusiasm for the world around him — what he calls Planet Sand.

Wearing earmuff-style headphones with a built-in radio — a welcome distraction from his racing mind — he lifted his little dog, Lola, by the straps of her life jacket and let her scurry up the beach, then grabbed the anchor from his 14-foot boat and tossed it into the water.

“That’s how you drop an anchor like a boss,” he said, before coming ashore from a trip to Cliff Island one morning this month. He’s been making a series of YouTube videos with his pointers but needs someone to record him while he demonstrates.

It’s all part of his plan to save Planet Sand, both the land itself and the world he’s created around it, complete with its own gods, laws and units of measurement (“too much or not enough”), as well as a website and merch meant to help fund the work needed to protect it from very real-world environmental threats.

Kern, 47, knows that most people who fantasize about living on their own island aren’t picturing this — what his video editor Mark Dunton calls “‘Robinson Crusoe’ meets ‘Trailer Park Boys'” — but this is his dream.

“We are a 10 out of 10, private, all-inclusive planet,” Kern said, and he’s the Sandkeeper, in charge of beach services, search and rescue, and the fire department, as well as serving as judge, jury and executioner. “We’re not a democracy out here. We don’t have Earthly politics.”

Its inhabitants are the Maniac Men — their “gang symbol” is two Ms made with the three middle fingers on each hand, hanging down from outstretched arms — but there’s really only one.

The name is meant to reflect the particular brand of hardy people who are crazy enough to spend their life on the coast, Kern said, but it’s also a nod to the struggles with mental illness and addiction that dominated his life for decades, spent in and out of treatment programs, hitchhiking across the country, living under bridges and locked up in jail.

Sober for more than six years, Kern started coming out for camping trips that got longer each year until he was spending most of the summer on the island — a purchase that his parents, who both worked as corporate real estate paralegals, made with an another couple in the early ’90s after it came up over dinner one night.

Then, it was something cool to say and a destination for his family’s trips on their sailboat. Now, it’s a lifeline for Kern that’s helped him find serenity and purpose, and he’s determined to make sure it doesn’t go away.

“It’s just being out here, to be away from all the people and hubbub,” he said. “I just feel like I can take over the universe.”

GETTING THE WORD OUT

Magical thinking is part of his diagnosis, schizotypal personality disorder, but his fears about the environmental threat to Planet Sand are far from imaginary.

Big storms in recent years have taken a toll on the shoreline, and Kern spends much of his days hauling rocks out of the water (his way of reversing rising sea levels, he says) and building a wall to protect the land from further erosion.

“The gods of Planet Sand laugh at Earthlings,” he said about how much money is wasted on things like war. “If we used it on the environment, we wouldn’t have problems.”

To make sure Planet Sand lives on in perpetuity, Kern estimates he’d need “about a million billion dollars,” to pay for equipment or people to help him, and he’s trying to start working toward that by capitalizing on his unique lifestyle and personality through YouTube.

He’d already been posting rough videos of his life on the island when he met Dunton about three years ago, while they were both outside a facility in Old Orchard Beach, each waiting to talk to someone about a job.

Kern asked if he wanted to see pictures of his island and told him he was looking for help getting the word out about it. Dunton, who has a background in computers, offered to do what he could, setting up a website, editing some of his videos and, this summer, encouraging him to post shorts once a week while he’s out there.

“Now, we’re starting to get thousands of hits,” Dunton said, but with 452 subscribers this week, the channel was still short of the 500 needed to start making any money, let alone the amount Kern has in mind. Still, he wholeheartedly believes in the potential he has as a content creator.

“I’m going to be rich and famous,” he said. “I have to be to save Planet Sand.”

THE VIP TOUR

Kern’s biggest fans have come by way of Casco Bay — boaters who have spotted signs of life on the little island and been curious enough to ask to come ashore.

Repeat visitors include the Chebeague Community Sailing School, which stops by at the end of each of its two-week sessions for a picnic and awards ceremony for the kids, and, this summer, Ford Reiche, the Maine businessman with a passion for preservation who bought and restored Half Way Rock Light, 4 miles off of Harpswell.

Reiche first noticed the sign on Sand Island, with Kern’s website and phone number, this spring and sent him a message saying they were neighbors. He’s been back a half-dozen times since, bringing tools to loan or guests for a tour from Kern “because he’s such a good host,” Reiche said.

Among them was an intern from the University of New England marine sciences program to whom he wanted to show the work Kern was doing to combat the effects of Mother Nature on the uniquely exposed island.

“He’s calling attention to the cause,” Reiche said. “We all need to do our part, and every bit helps, and he’s making a difference on Planet Sand.”

If it’s a nice enough day, Kern can count on getting visitors, he said, and it’s never more than three days before someone stops by. Everyone who does gets a business card that’s good for a free ice cream at the Cliff Island Store & Cafe, where Kern refills his water jugs every couple of weeks.

“You just never know when something’s going to be happening on Planet Sand,” he said.

On that Tuesday in August, two kayakers came over from their family’s summer home on Chebeague Island.

He took them up a walkway, by street signs for Main and West Elm that stick up like an intersection in the middle of the dune grass. He found them at the dump in Yarmouth, the town where he grew up and his parents still live. He calls them every morning and night and sees them when he goes to the mainland for groceries every month or so.

Past what he calls Monarch Mansion, a patch of milkweed that attracts butterflies, is the Winch Tower/Religious Thing, a wooden structure adorned with buoys, ropes and chains that have washed ashore.

“Stay in the middle; there’s poison ivy on the sides,” he warned, and pointed out the bittersweet, too, an invasive plant that he believes is helping keep the ocean from encroaching further, and that Lola dodges in and out of.

The tour follows past a rotted-out work bench and a cove of poplar trees, around to Flat Rock Beach with its patches of sea lavender and eventually back to The Great Wall of Planet Sand, what he hopes will keep it all in place.

“What I’m trying to do is have a positive, fun experience,” he said about why it’s so important to him to preserve Planet Sand. “When people come out here, they make lifelong memories.”

Right now, the rock wall is primarily protecting the land around the hut where he sleeps — what he calls the Garden Shed Tree Fort, a temporary structure made of construction trash he collected on the mainland. As of Thursday morning, the town of Chebeague Island, where the property taxes are paid, said no one had raised concerns about the structure or Kern’s activity on the island, and Kern believes it’s fine for him to have it there.

Ideally, he’d like to extend the rock wall around the whole island. He just doesn’t know if he’ll have enough time, before the next big storm or ever.

ON SOLID GROUND

A “10 out of 10, 5-star, VIP triple platinum tour pass” gets access to the rooftop of the Garden Shed Tree Fort. Kern rarely goes up there himself, aside from on the Fourth of July, when he has a view of all the fireworks displays between Cape Elizabeth and Harpswell.

“We’re very friendly with the United States,” he said, explaining why there’s an American flag on Planet Sand. “We get a lot of American visitors.”

Kern doesn’t know yet where he’ll be going when he leaves the island sometime after Labor Day. Just before he moved out here in mid-June, he and his neighbors all got evicted from their building in Old Orchard Beach so the owners could renovate it. He had been living there for free in exchange for working as the building manager.

“I’m kind of homeless, I guess, right now,” he said.

He hopes to find another place in Old Orchard Beach, where he has a support system, including the United Methodist Church, a small congregation he started attending while he was in addiction treatment at Milestone Recovery, then quickly began helping in any way he could, trustee Karen Wade said.

That’s come to include mowing the lawn, hauling away snow, replacing light bulbs and fixing plumbing, roof leaks and crumbling foundations.

“He is always the first person we call on when we have questions or need something done,” Wade said.

The most he charges is the cost of materials. He sees it as a way to make amends for his past.

“I’m trying to make up for the damage that I caused,” he said.

After all the scary situations that addiction got him into, his parents couldn’t be more pleased to see him find a life and a place that make him happy.

“It was hell for us, hell for him, and now look at him. It’s like Jekyll and Hyde. He’s back to his old self,” said his mother, Brenda Kern, recalling the happy-go-lucky boy he was before the bullying started in high school and things went downhill from there.

Sometimes, when he speaks to other people in recovery about the role Planet Sand has played in his life, he said, they’ll ask, “So, what, do I need an island to stay sober?”

He explains that it’s a metaphor, that everyone has their own version of saving Planet Sand, whether it’s raising kids, being in nature or making art.

“If you don’t feel like you fit in anywhere, make your own thing,” he said. “That’s what I did.”