His troubles worsened eight days ago, as violent winds tore part of his front sail rigging loose. He worked through the night on deck in 12-foot seas, strapped into a harness, water cascading all around, trying to furl the sail and gather its rigging.
"I've been telling my friends to pray for him because the next four days could be a long four days," Marianne Sunderland said Monday, in reference to her son's push toward Mauritius.
"It's hard because I know how tired he is. He's not eating right. He can't cook or even clean up when it's rough."
Persistent problems prompted a detour to a nearby island, further delaying his arrival at Mauritius, where his father, a shipwright, awaits with tools and a new boom.
Steady as he goes
Remarkably, when Zac was reached Tuesday evening -- Wednesday morning in the Indian Ocean -- he sounded as calm is if he were at home on the sofa.
He confessed to eating cold meals from a can, to not having energy to wash after so much work, and to missing his family, whom, with the exception of his father, he has not seen since July in Hawaii.
But he has visited so many amazing places, made so many unforgettable friends.
Sadly, he'll spend Thanksgiving and his 17th birthday, Nov. 29, hurrying to Durban, trying to beat the storm season.
What he may not know is that he'll take from Mauritius dozens of birthday presents and "a microwave cake complete with candles," his mother said.
With luck, he'll have some leisurely moments to savor them.