Zac enjoyed the Cocos Keeling Islands in the Indian Ocean, halfway between Australia and Sri Lanka, and he loved his three-week stay in Cape Town, South Africa.
"It's not negligence," says Marianne, a mother of seven, who points to her eldest son's extensive sailing background and adventurous spirit. "It's just that we're not accustomed to living inside the box. We pay our taxes and do things legally, but what's the harm in letting a kid pursue his dream?"
Sunderland set sail after his sophomore year at Grace Brethren High School in Thousand Oaks, intent on breaking a record held by Australia's David Dicks, who completed his circumnavigation when he was 18 years and 41 days old.
Sunderland turned 17 on Nov. 29 in the Indian Ocean. He celebrated with a just-add-water microwaveable cake. It was a lonely experience, but he was becoming worldly beyond his years.
However, a middle-class American teenager matures only so fast. During an extended stay for repairs on St. Helena, a flyspeck in the South Atlantic about midway between Africa and South America, he became cranky and complained on his Facebook page that he was "stranded on a deserted island."
Irked by his attitude, his mother vented publicly on his blog: "There are times when he seems far older than his years and others that just make you scratch your head and wonder if this is the same kid who just sailed halfway around the world."
The adventure has taxed his parents. Laurence has tried to keep to a work schedule but has routinely flown off to tend to Zac's injured vessel. Marianne, with a house full of home-schooled children, has been working full-time on logistics.
The trip has been partially funded by Clearpoint Weather, a provider of digital weather information for sailors and pilots; Bandacorp, which designed and maintains Zac's website (zacsunderland.com); and Produce for Kids, a nonprofit that promotes healthy diets for children. Still, Laurence says the family has spent $150,000 and hopes to recoup some from the sale of a DVD that will feature footage from Zac's journey.
But neither parent expresses regret. On the contrary, Laurence says, "this has meant something far bigger than words can express.
"I don't think Marianne or myself have realized until now how much of us has been out there with him. But it'll be a big day when he gets back and we'll be very proud, because Zac will have achieved something that very few people will ever be able to achieve, and it has changed him and it'll be with him the rest of his life."
Zac sails into Puerto Vallarta's vast Banderas Bay with a mast braced by his handiwork with halyards, just as Tropical Storm Andres is upgraded to a Category 1 hurricane.
The sea is jumbled, and driving rain and wind hamper visibility. David Ramirez, aboard a skiff from Paradise Village Marina, arrives to guide Sunderland to dock.
The sailor disembarks looking disheveled and with squinty eyes, but that's been his look at almost every stop: as if he just woke up after a late night out with friends.
A day later, during an interview, he talks about a recent string of setbacks along the Mexican coast -- he had most recently ducked into Manzanillo to dodge the tropical depression.
But he does not complain about the storms or the previous two weeks, spent in a windless swelter, where the ocean and air and the water he drank were 90-plus degrees.
Instead, he talks about grabbing his surfboard and tackling the 25-foot waves breaking around the point. He offers a reporter his second board, then remembers it broke in two somewhere on the planet.
Laurence has begun rebuilding the bulkhead, while Zac explains that were it not for this misfortune, he might have continued on a northerly course and been swept up by Andres.
A day later, the storm has spun to the west and dissipated. Intrepid has a clear weather window, a new bulkhead, a scraped hull and tuned sails.
That late June evening Zac is underway, hoping to arrive home in two weeks. The boat is faintly visible from the north end of Banderas Bay. The pale white triangle looks like part of a painting, subtly contrasting with a dusk sky swathed in pink and orange.
Then it glides between two of the coal-colored Tres Marietas Islands, and it's gone.