Pictures of the boat, taken by a Quantas jet chartered to find the teenager, show the mast snapped off at the deck.
By radio, Abby said she had been knocked down four or five times before losing the mast in 50 to 60-knot winds and 35-foot seas.
"Now that she's made contact with rescue officials she knows helps on the way and she just needs to -- like we've always said -- take care of yourself, take care of the boat," said Abby's mother, Maryanne Sunderland.
"It's so large, the fact they found her is marvelous," said retired U.S. Navy Adm. John Bitoff of San Francisco.
Bitoff knows the Indian Ocean well and says with its unpredictable, brutal storms it's no place for a teenager.
"If I were her father, I would have done everything I could have possibly done to not let her go, but I'm not her father," said Bitoff.
The Coast Guard station in Alameda was the first to report the emergency beacon, or EPIRB signal, from Abby's yacht. It came in at 5 a.m. Thursday morning, launching the rescue effort.
"The beauty of this case is she had EPIRB and the Australian -- the Quantas airline that they chartered -- flew directly to her position and established communications," said Douglas Samp with the U.S. Coast Guard.
Abby was following in her brother's footsteps. He sailed around the world at the age of 17.
"I know Abby is very capable and we're sure she can handle the situation she's in," said Abby's brother, Zac Sunderland. "But at the same time, it's weird being on the waiting game side over here."
Abby was attempting to break the world record to be the youngest to sail solo around the world without stopping. Her parents have come in for a good deal of criticism for allowing the 16-year-old to make such a potentially dangerous voyage.
"I don't know what she's doing in the southern ocean as a 16-year-old in the middle of winter, it's just foolhardy," said Australian round-the-world sailor Ian Kiernan.
Abby's father, Laurence Sunderland, bristled when asked how he is handling that criticism.
"Listen, how many kids die in car accidents every year, teenagers?" he asked. "Should we stop every kid from driving a car? I mean the sort of logic that they're using is just ridiculous."
"The fact is that Abby is an accomplished sailor," said Marcus Young, commodore of the Golden Gate Yacht Club. "She's not a novice, she's definitely young, but she's not a novice. This isn't something that is necessarily out of the norm, and I think it's going to be different for every kid."
Kalin is the sailing director at the St. Francis Yacht Club in San Francisco. He's worried the next kid to try this will be 15 years old. He says it's time to regulate who can set sail alone.
"You don't want to open this up as a contest right? If every parent who wants their kid to achieves something great goes and does this, there's a good chance we'll lose a lot of kids in the ocean," said Kalin. "Eighteen is like the legal limit for a lot of things, so probably to do same thing like this, I think it is probably more appropriate that 18 is the limit."
In the Netherlands, a 13-year-old announced she was going to try to become the youngest person to sail around the world, but the government there passed a law prohibiting her from making the trip.
