Abby Sunderland rounds Cape Horn

Rain driven by freezing wind pelted her 40-foot sailboat, but Abby Sunderland was in remarkably good spirits early Wednesday afternoon.

That’s because the 16-year-old from Thousand Oaks, while friends back home were coming off a refreshing spring break, had just rounded Cape Horn between South America and the Antarctic Peninsula.

She had safely traversed a passage known as the Mt. Everest of the yachting universe, a mariners’ graveyard fraught with unpredictable gales and gargantuan waves.

“It’s the milestone I’ve been waiting for,” the budding adventurer said, when reached via satellite phone, minutes after she had crossed from the Pacific into the Atlantic. “It’s pretty much the hardest part of my trip, and now it’s over so it’s really great being here.”

That might not be true. Sunderland’s controversial bid to become the youngest person to sail around the world alone, nonstop and without material assistance, could become significantly harder.

It’s a journey similar to that of Australia’s Jessica Watson, who is five months older than Sunderland. But whereas Watson began at an ideal time in mid-October, and is currently in the Indian Ocean on the home stretch, Sunderland left on Jan. 23, almost two months later than planned, because of boat issues.

And it has taken nine weeks to reach Cape Horn, so she’ll begin the Southern Ocean portion of an easterly journey, which entails crossing the Atlantic and Indian oceans beneath Africa and Australia, with the onset of the Southern Hemisphere winter dangerously close at hand.

“My biggest hope is that she has the maturity to wait out any nasty weather rather than push too hard for a record and risk getting into trouble,” said Charlie Nobles, executive director of the American Sailing Assn.

Don McIntyre, a renowned Australian adventurer who has solo-sailed around the world, added: “I think the biggest question mark will not be the Horn. It will be the Indian Ocean and under Australia. It can be worse there, especially late in the season, and she will be close to winter then. This will be Abby’s biggest challenge.”

Weather experts are helping to guide Sunderland, who embarked five months after her older brother, Zac, completed a westerly solo circumnavigation at 17, after 13 months and multiple stops. Her parents have vowed they’ll persuade Abby to dash to the nearest port if conditions warrant.

Meanwhile, Laurence and Marianne are deeply proud. “Abby has amazed me with her attitude and everything else, so I know she has the stamina to do this,” Marianne said.

During the interview, Abby spoke of a blustery gray universe and being unable to heat her cabin above 50 degrees. She often forgets what day it is.

Asked what she misses most, she responded, as if dreaming of it: “Warm showers ... warm, freshwater showers.”

Nothing stays dry, so she sleeps, mostly in catnaps, in foul-weather gear. She drinks desalinated seawater and subsides exclusively on freeze-dried food, which she consumes from a bag in which she pours hot, desalinated seawater.

Back home, nobody misses Abby more than her 5-year-old sister, Katherine. The two have always shared a bedroom and Katherine has refused to sleep in the room since Abby left.

Then there’s Zac, who has reminded Abby, teasingly, that so far there is still only one successful solo circumnavigator in the family.

Though that’s true, Zac chose the Panama Canal instead of treacherous Cape Horn, and that’s something Abby will point out the next time they talk.

sports@latimes.com