The MV Butiraoi, a 17.5m wooden catamaran, was reported overdue last night after leaving Nonouiti Island, Kiribati on January 18. It was headed for Betio Tarawa, the largest township in the capital - a 260km journey expected to take two days.
Local authorities began searching for the vessel after it failed to arrive on January 20 as scheduled.
The Rescue Coordination Centre of New Zealand and the New Zealand Defence Force have joined the search.
Air Commodore Darryn Webb, the Air Component Commander, said a Royal New Zealand Air Force P-3K2 Orion aircraft left Auckland at 6am to help in the search following a request last night from the Rescue Coordination Centre New Zealand.
Webb said the Orion was expected to arrive at the search area around midday.
"We are always ready to play our part at home and in the region to help those in need," he said.
Local authorities said the vessel ran aground and underwent repairs to its propeller shaft before it left Nonouti Island. The boat was equipped with a high frequency radio but it was not known whether there was enough fuel or water on board.
Searchers were looking for a vessel with a dark blue hull and yellow accommodation quarters, with an estimated 50 locals on board.
RCCNZ Senior Search and Rescue Officer John Ashby says the New Zealand Maritime Operations Centre and Kiribati Tarawa Radio were broadcasting for sightings on maritime radio.
Contact was also being made with all islands along the route for sightings.
"We are doing everything we can to locate this ferry and its passengers. We understand the vessel underwent repairs to its propeller shaft just before it departed. This may have contributed to problems navigating the journey.
"The weather in that part of the Pacific is currently moderate with some swells."
