The send-off felt a little like the dawn of a new adventure, a trip to uncharted territory — a discoverer’s voyage to the new world or the Wild West. And the subject of the voyage is almost as mysterious and misunderstood, its public perception more determined by stereotypes than hard facts. The biology and behavior of great white sharks, the top predator in the Atlantic ecosystem, remains poorly understood.

A 126-foot research boat set out from Woods Hole at 2:30 p.m. on Tuesday afternoon under a bright blue sky, embarking on a rare opportunity for scientists to get up close and personal with these apex predators. The 31-day voyage will fish mostly in mid-cape Chatham waters, where an estimated 15,000 gray seals attract the whites to feed. The crew will add to the chum slick concentrated in this area in order to capture the sharks, temporarily hold them for research purposes, tag them, and send them on their way.

Led by OCEARCH, a marine research nonprofit which receives funding from major corporations, the project “will be the most in-depth study of Atlantic white sharks to date,” said Dr. Susan Avery, president of Woods Hole Oceanographic Institution, in remarks to the news media Tuesday afternoon in Woods Hole before the boat left the harbor. Below the deck, the engine room seethed with the noisy workings of several pieces of machinery provided by Caterpillar, one of the large corporations funding the OCEARCH expeditions.

By Wednesday evening the crew had attracted as many as three white sharks to the boat, since chumming began Wednesday around 8 a.m., said lead researcher Dr. Gregory Skomal, a former Vineyard resident. He said he can’t be sure about the precise number because it’s possible they saw the same shark twice. Though the sharks are somewhat shy, and hesitant to bite, crew members are pleased to have determined that they can attract the sharks, and that they are in fact present in Chatham waters.

“This is encouraging,” Mr. Skomal said. “There is a lot of excitement in the air.” The boat is anchored about a quarter of a mile off the coast of Chatham.

The expedition is part of the global shark tracking mission of OCEARCH, which has already completed 17 separate expeditions, most recently a 48-day voyage to Trinidad and South Africa. The 126-foot vessel is designed to accommodate the largest of the ocean’s predators, and has the tools to keep the sharks alive on board the vessel for 15 minutes, while scientists extract information for their research, all the while hosing down the animal to keep its gills supplied with oxygen. The vessel’s progress can be followed on the OCEARCH website, where shark-tracking information is uploaded in real time. Shark migration patterns are still much of a mystery, as are their mating, feeding and gestating behaviors.

The boat is equipped to catch, study and tag as many as 20 white sharks, a significant increase from the two sharks tagged in Cape Cod waters last year. Mr. Skomal, who works for the state Division of Marine Fisheries, said he’s confident there are at least six great whites in Chatham waters right now, and probably more.

In the 15 minutes the shark visits the vessel, scientists will extract muscle to be biopsied, perform ultrasounds on female sharks and measure the reproductive organs of males. They will also take fin clips, and study tissues to determine the content of the sharks’ food. The information will inform as many as 12 research studies on the fish. The tags applied to the fish may enable the scientists to track their behavior for three, four or even five years.

Atlantic white sharks are not a species currently protected by fishing regulations, but Dr. Simon Thorrold, a fish ecologist with WHOI, said they probably should be.

“White sharks are not listed as endangered in the Northwest Atlantic, but that is almost certainly because we don’t know enough about their population size,” Dr. Thorrold said. The species’ top spot on the food web means their demise would wreak havoc on the entire ocean ecosystem.

Ms. Avery called them “the polar bears of the ocean.” The expedition is focused on the white shark species partly because of its charisma, Mr. Thorrold said. Considering their fame, it’s surprising how little we know about them. “They’re the third largest fish in the ocean, they get all this attention, so if we don’t know anything about white sharks, that shows you how little we know about anything else in the ocean,” he said. The expedition aims to improve the public profile of the three-ton predators by gathering more scientific data about them and sharing it with the public.

“Once that data comes in, the tone of the conversation turns from the theme music of Jaws to one of curiosity,” said Chris Fischer, founder of OCEARCH. Patterns that emerge in terms of shark feeding behavior may inform beach safety regulations, he said.

Much of the local research on sharks in the past has relied on basic tagging tools and the harvesting of tissue samples from deceased sharks caught in tournaments and commercial fishing expeditions.

But Mr. Thorrold said studying dead sharks is a 20th century approach.

“Once you kill the shark, there is really only so much you can learn about them,” he said. “You can learn about what was in its stomach at that time, you can learn whether it was pregnant or not at that moment in time. [But with this new technology], we are putting a tag on it and we are learning about it two years later.”

OCEARCH will likely not return to Cape Cod waters for four or five years, Mr. Fischer said.

“We are going to maximize the 15 minutes we have with that shark,” Mr. Skomal said. “Me, I’m just super excited to get out on the water and start learning.”

In periods of down time, the crew rehearses the shark drill to make sure a “well oiled machine” greets the fish when the smaller boat, the Contender, tows in a shark, and he or she is heaved over the side of the vessel. “We have it all choreographed,” Mr. Skomal said.

When they are not preparing for a shark catch, the crew members spend a lot of their time “staring at the water,” Mr. Skomal said. “You can’t catch a shark until you know it’s here.” The team takes turns sitting on the highest perch with a pair of binoculars, looking out for sharks.

It’s hard to predict their behavior in relation to the boat when they do come around, said deck hand Alex Snow, because each shark has its own personality. “Some like to stay on surface, some stay below,” he said. “They’re all individual, they’re all different.” Mr. Snow is one of the seamen who’s signed up to “lay body parts on the line,” and go in for the catch, as Mr. Fischer described it. In fact, this is the first expedition on which he will join the crew in the Contender, a dinghy that goes out to catch the shark. Mr. Snow said the fishing isn’t much like Jaws; no exploding oxygen tanks, no shark cages.

He was hired for the expedition three and a half years ago, right out of college. He graduated with a degree in economics, but he has a strong love of the ocean and has been living on the boat ever since. “I’m a one in a million guy,” he said. “Very lucky.”