NORTH BEACH HAVEN, N.J. - The front door establishes the whimsical humor to be found inside: "Poor Helen," reads the sign that greets visitors to Helen and Thom Sweeney's tiny seashore home on Long Beach Island.

It's a reminder of the "home" that preceded this one. Poor Helen was the apt name of a 34-foot boat on which the Sweeneys and their three sons vacationed each summer. And, yes, it was mighty crowded, with amiable Helen Sweeney handling the daunting domestic side of things.

So Helen and Thom's 1981 purchase of what has now been fondly dubbed "The Shack" was a big step up. The place was, in their words, "a total wreck." But Thom, an artist, a designer, and a former adman, saw what this old net house of a historic island lobster fishery could become.

The history of the place, which proudly bears a historical marker from the Long Beach Island Preservation Committee on its porch, is murky. Some suggest it may have been the bunkhouse for the lobstermen; others recall it as strictly the place where lobster nets were stored. While no one is sure of the year it was built, the net house is believed to have come along from about 1915 to the early '20s.

When a major storm hit Long Beach Island and the fishery was destroyed, the little net house survived. Decades later, it even made the pages of Island Album: Photographs and Memories of Long Beach Island, a look at LBI's architectural history by Margaret Buchholz.

But its location, even more than its history, won over Thom and Helen when a friend advised them that the 12-by-24-foot cottage was for sale. Situated literally on the bay with sweeping views, it is, Thom suggests, a bit like living on a houseboat - without the rocking.

"Before the Realtor showed us the house, she warned us wearily that she'd shown it about 300 times to disappointed potential buyers who couldn't imagine actually living in that space," Thom recalls. "She warned us that it was like buying a single hotel room on the water."

The Sweeneys, year-round residents of Southampton, Burlington County, recall what they saw on that first visit, and it was hardly irresistible. They saw a drop ceiling, the decks were upended from ice storms, the floor was orange linoleum, and the place was . . . incredibly small.

But Thom went home that day and started sketching. And by midweek, he assured Helen, a bit less enthusiastic but still willing, that this would be a terrific summer place.

"When I called the Realtor, she told me it had already been sold. I was devastated, but gave her our number just in case the deal happened to fall through," Thom says. "Two weeks later, it did."

So the Sweeneys became the proud owners of what is believed to be the smallest dwelling on Long Beach Island. And they went to work "charming it up."

Windows were replaced, the ceiling was raised, a loft space was created, and wraparound decks were repaired. A soft gray paint on its cedar-shake exterior replaced the brown that had grown dark and damaged. Window boxes and white fencing set off the facade, and wooden lobster buoys turned up on decks and even in flower pots.

The Sweeneys set out to make The Shack's interior as inviting as the space allowed. They succeeded.

In a color palette of cheery blues and yellows, the interior has an open-flow living space, a dining nook with white table and chairs, and a compact kitchen with a dishwasher. Every inch is accented by items with a nautical tilt.

An antique turtle decoy found by Thom, who scours flea markets in his spare time, dominates one wall. An oversize replica of a soft ice cream cone sits on an end table. Nearby are a neutral love seat and a sofa bed covered in a fish-theme fabric. The tiny bathroom, in the spirit of The Shack, sports monogrammed towels that read "Poor Thom" and "Poor Helen."

As a conversation piece, the Sweeneys framed a 1942 newspaper notice about trash pickup on the island.

The loft space above one end of the cottage holds overflow. Outside, three Sweeney boats bob in the bay.

Brad, their youngest son, admits that The Shack was "every kid's dream" for the brothers. "I can't imagine any place in the world that could be more fun for boys growing up," he says during a visit with his dog, Casey, who is clearly at home in the cottage and on its decks.

"Close quarters, close family," he says.

Brad also has contributed his handcrafted wooden fish accessories, including his favorite, affectionately called Mahi Lisa, carved of cedar and painted in bright colors. A wallpaper border around the house features signal flags.

For Thom, a partner in the upscale design firm New Home Interiors in Lakewood, coming to The Shack is always pure joy.

"I spend most of my working life surrounded by formal things, so I enter a different zone when I come here and sit by the bay. It's my Zen," he says.

And for Helen, who has officially retired from the rigors of rearing three spirited sons, there is a different bonus: "The kitchen down here is basically closed. We do breakfast and lunch, but it's mostly out to dinner. And that's perfectly fine with me."