The temperature hovered around 20 degrees one recent morning, and ice shards lay like broken windowpanes along the edges of Boston Harbor. But inside his 36-foot powerboat, Rich Westcott was toasty.
With just a light blanket and a single electric heater, his sleeping berth was warmer than many Boston apartments.
“The boat stays warm no matter what the temperature drops to,” said Westcott, a 65-year-old civil engineer who has lived on his boat about five years.
Throughout this brutal winter, as Bostonians awoke and tromped out to shovel sidewalks and clear cars of snow, a hardy band of outliers such as Westcott has been greeting the days from inside cozy rooms that bob gently with the current.
At Charlestown’s Constitution Marina, about 150 men and women, and a handful of children, live year-round on sailboats and powerboats, most built for warmer latitudes and part-time residency.
But these self-described “live-aboards” say modest modifications afford them a lifestyle uniquely in tune with the natural world and their marina neighbors. Some insulate the hulls of their boats or install propane heat, while others trust in modest electric radiators to stave off the chill.
During the winter, almost all boats in the marina are shrink-wrapped in thick plastic to keep out the elements, creating a greenhouse atmosphere on sunny days that makes decks hospitable while other outdoor spaces are frigid.
“I’ve been warmer this winter than I was in our big apartment in Somerville last winter,” said Michael McLinn, 35, who has lived in the marina just a few months. McLinn relies on two electric heaters aboard the “Gaia,” the 42-foot sailboat he shares with girlfriend Kirsten Sward.
What McLinn and Sward see through the shrink-wrap around their deck is a big part of the marina’s appeal for them and other live-aboards. With the marina nestled between the Charlestown Bridge and the Navy Yard, the couple can look across the harbor to the North End and gleaming towers of the Financial District, where some boat dwellers, including Sward, work.
“You can’t get cheaper waterfront property,” said Sarah Garant, who lives on a 45-foot sailboat with her husband and their daughter, Maya, who will turn 2 in June.
Parenting on the water presents challenges, but the Garants are engineers and amateur carpenters, and they have built a custom gate that turns a sleeping cabin into a combination crib and playpen for Maya.
The cabin is already child-friendly, Garant said. Corners are rounded, cabinet doors latch shut for safety on choppy waters, and the space makes an inviting play area for a curious toddler.
“It’s a big jungle gym for her,” Garant said. “She just learned how to climb up in the bed, and she loves that.”
For adults, too, living on the water requires adjustments and sacrifices, in any weather. Westcott, a self-described pack rat, gave up his flea market habit as a concession to tight quarters. Still, like most, he rents off-site storage.
The boats require regular maintenance, some of it done by Dave Nelson, 38, a handyman who has lived in the marina for six years. He warned that a floating home is not for everyone.
“You have to bring everything into the boat, and you have to take everything out of the boat,” said Nelson, who lives with his girlfriend, medical student Christina Carr.
That includes trash and “black water” — sewage — which marina staff empties regularly into a pump-out boat.
There can be perils. A leak concealed below the waterline caused a 49-foot Gulfstar owned by live-aboards Jeff Doretti and Walter Hope to sink last month, and late Wednesday an uninhabited 24-foot boat burned in a fire whose origin is so far unknown.
Such calamities bring resident closer together, they say.
Doretti said neighbors helped raise more than $16,000 to aid him and Hope through the GoFundMe website.
“The minute it happened, they offered their food; they went and got clothes out of their boat,” Doretti said. “In 10-degree weather, they stood on hours on end just to be there.’’
Doretti also praised marina co-owners Peter Davidoff and Tom Cox, who help foster that community while making sure docks are kept clear of snow and that residents have electricity, clean water, and facilities for showering and laundry.
“I think this is one of the last communities where people actually know their neighbors,” Cox said.
Marina residents also came to Nelson and Carr’s aid, taking a collection to cover their slip fee when Carr’s mother died and they had to travel to attend the funeral, giving up several days of work.
Despite that hospitality and the pleasures of life on the water, at least one live-aboard has had her fill of coming home to an ice-cold boat. Kate Welti, a resident for three years, relies on a diesel heater with a flame that she cannot leave lit when she goes to work as a lawyer for a downtown firm.
“This year, it’s just been too much to endure,” Welti said of the long winter.
Welti had a proposition for a stranger she met on the dock: “You want to buy a boat?”