BERKELEY, Calif. — John Dinwiddie and Diane Brown own a house with twin engines.

It began its life as a Delta barge, later became a floating hot dog and beer stand, and finally a marina fuel dock, before being converted to its current use as a house — yes, an actual house, albeit one that’s tethered to a slip on at the Berkeley, California, Marina.

“Here are the engines,” Dinwiddie says, throwing open a trap door in his living room floor. The house bobs ever so slightly in the water as Dinwiddie, a lifelong boatman, shows off the vintage engines in the narrow crawl space. “They haven’t turned over in 30 years.”

The floating home — which cost $250,000, with bedroom, kitchen and swanky bath — sits atop what is essentially a floating box made of concrete and fiberglass. The whole setup may strike some as “kind of cuckoo,” Brown jokes. But it makes solid sense for her and the hundreds of other homeowners who live, often affordably, in dockside floating homes like this one or aboard their powerboats and sailboats in marinas throughout the Bay Area.

The sense of peace and quiet, of occupying vast spaces at the edge of the mad city, is priceless, they say. And in many cases, it is lighter on the wallet than the land-based equivalent.

In a region where the median home price is more than $700,000 and the typical rental of a two-bedroom apartment in Berkeley or Oakland tops $3,000, a floating home payment and slip fee of around $2,000 sounds reasonable, if not dreamy.

Sausalito, just north of San Francisco, is the region’s capital of aquatic living, with more than 400 floating homes, many palatial. But tucked throughout the East Bay are a couple dozen marinas catering to a variety of lifestyles and fostering a sense of community that harks back to another era. Their amphibious residents share a deep-seated love of the water, of course, as well as a penchant for DIY living — and views of the glittering bay and miles of sky, views typically associated with multimillion-dollar penthouses.

Dinwiddie, who makes his living as a harbormaster at a yacht club, and Brown, a hospital facilities manager who lived on her sailboat for a year in the Sea of Cortez, make monthly payments of $1,330 on their 600-square-foot floating home, along with a monthly slip fee of $660. “It’s not exactly cheap,” Dinwiddie says, likening the place — which he and his wife have torn apart for renovations — to a studio apartment. “But we don’t need a lot of room. We’re not much for sitting.”

In fact, they plan to sell the house in two or three years and sail to the South Pacific in their 38-foot sailboat.

It’s the life aquatic.

“Everyone’s trying to get back to their original water memories,” says Krista Lettko, office manager at the Emery Cove Yacht Harbor in Emeryville, north of Oakland, where she lives aboard the Ondine, her 40-foot Nova Sportfisher powerboat. She is 26, grew up sailing with her family and has lived on boats off and on since college, even though “a lot of things are so unglamorous. I’ll spend Friday nights in my engine room, or figuring out where the leak is coming from in the bilge.”

But, oh, the sunsets.

She and boyfriend Astor Kuiperi, a kite-surfing instructor from Aruba, where Lettko used to live, enjoy them from their back deck. They pamper a small herb garden and arrange a bouquet of sunflowers on the patio table. Often, the couple will pop into their backyard — the water — and paddle over for a glass of wine with Lettko’s sister Kelsey, who lives on her own powerboat, two docks away in the same marina.

Her monthly costs — $1,200 boat payment, $400 berthing fee, $250 liveaboard fee and maybe $50 for electricity — total about $1,900. “I’m paying the same thing as my friends who live in apartments in San Francisco,” she notes, “and I’ll own my own boat in a few years.”

One recent morning, Lettko and her boss — harbormaster Diane Isley, born in a boatyard in Indiana — toured a visitor through the marina. It is a “dockominium,” offering an unusual condo-like arrangement to the owners and renters of its 430 slips. About 10 percent of the slips are allotted to “liveaboards,” the folks who live, cook, sleep and even raise their kids aboard their boats.

It was a flawless day on the bay, with clear views to the Bay Bridge.

Lettko visited her friends Gordon and Lara Scriba and their children Logan, 5, and Osian, 2. The toddler was swinging from the overhead grab rails in the living quarters of the family’s 41-foot sailboat while Lara sliced bananas and strawberries for the kids.

Lettko also stopped by the deluxe Grand Banks yacht owned by buddy Wayne Goldman, a veteran of Silicon Valley startups. Goldman recently had been living on land in San Francisco’s SOMA district, but he “couldn’t wait to get back to a boat.”

And she dropped by the sailboat owned by friends Jennifer and Joseph Boyle, whose 2-year-old daughter, Ruby, was sound asleep, netted into her berth below while Ray Charles sang on the radio.

Jennifer and Joseph met while working as international travel guides, and learning to sail “makes marriage interesting,” Jennifer says, laughing. When they can’t figure something out, they check instructional videos on YouTube.

It’s a 20-minute drive from Emery Cove to Barnhill Marina, a hidden oasis on the Oakland Estuary, across from the city’s Jack London Square neighborhood. Built in the mid-1960s, Barnhill is its own neighborhood of 42 floating homes: squat or tall, resembling dollhouses or gingerbread Victorians, all unique and many boldly colored, with front doors opening onto creaking, gently rocking dock-ways alongside which are parked sailboats, kayaks and powerboats. Outside one front door in this bohemian enclave is a sign saying “H2OUSE.”

Another floating home has a “For Sale” sign in the window, but the sale is already pending, for about $390,000.

John Curley moved here nearly two years ago. From the rooftop deck of his two-story home, he can look across the water to the Transamerica Pyramid in San Francisco and the Oakland Tribune Tower. The neighborhood’s silence is broken only by the sound of a distant train whistle. What a setting: “Living around here is like being an expatriate and never having to leave the country,” he says.

He got a steal on the house and pays about $450 a month for its berthing fee, plus $12 in annual dues to the Alameda Floating Home Association. He leads “a sustainable life” in the charmingly ramshackle residence, painted a shade of turquoise that matches the trim of his cool little Donzi cuddy cabin speedboat. “I can go to Sausalito for lunch in my boat and be there in 20 minutes, and there’s no traffic.”

Formerly the deputy managing editor of the San Francisco Chronicle, Curley took a buyout in 2007 and has been reinventing himself. He has found success as a professional photographer and shoots weddings. Prospective clients come over for a glass of wine, sit for three or four hours and don’t want to leave.

He understands. He finds himself getting up early to watch the sunrise: “I wake up and I feel like I’m on vacation. Every day, the estuary looks different, the sky looks different. It’s the new life. It’s the life afloat.”