The 20m-long boat left Picton a week ago, heading for Tonga.
They decided to go to Fiji last night because of an equipment failure, then activated a distress beacon at 4am after going aground on the reef.
Rescue Co-ordination Centre spokesman Keith Allen said earlier today efforts had been made to contact boats in the area by radio.
He said unfortunately the nearest boat they've been able to contact is about 200km away, can only sail at about seven knots and will take 24 hours to reach Jungle.
Weather conditions were good at the time of the yacht's grounding, with no heavy swells.