The area is popular with tourists for shark spotting and Nicholson's team made their way in pitch darkness.
The A$10 million ($12.8 million) boat is believed to be a near write-off and still lies stranded high up the reef, having struck it at 19 knots.
"We're essentially shipwrecked," Nicholson said . "My major concerns are obviously for the well-being of my crew, and also everyone who may actually have felt for them last night as well.
"I've been making lots of calls on the sat-phone."
The grounding happened as Nicholson and his crew were making good progress in fifth spot in the 5200- nautical-mile second leg from Cape Town to Abu Dhabi.
Nicholson said abandoning his boat had been a very painful choice.
"When you talk about the tough decisions you have to make in life, I have to say that was number one for me, and it's one of those ones where, okay, we hit the rocks and we had massive damage.
Kiwis Rob Salthouse and Tony Rae.
"The immediate concern was just for people to be able to hang on to the boat and buy time until the situation got better.
"But the situation did not get better. I can't begin to describe how hard it was literally just to hang on. We had to spend seven to eight hours trying to hang on till daylight."
Nicholson said he had practised escaping the boat 15-20 times with the crew "without thinking we'd have to do it".
"And then towards daylight, like two hours just before daylight, the [keel] bulb broke off and the boat leaned over heavily. While that was happening, I made the decision that we were getting off."
Race organisers said a ferry service or supply boat would pick up the crew from the remote island within 48 hours and take them to Mauritius.
For more on the rescue click here.
- additional reporting NZME.
