HONOLULU - The U.S. Coast Guard said Monday that the two Hawaii women who were lost at sea for five months had an emergency beacon aboard their sailboat that was never activated.

U.S. Coast Guard spokesman Lt. Scott Carr told The Associated Press that their review of the incident and subsequent interviews with the survivors revealed that they had the Emergency Position Indicating Radio Beacon (EPIRB) aboard but never turned it on.

Parts of their story have been called into question, including the tropical storm the two say they encountered on their first night at sea in May. National Weather Service records show no organized storms in the region in early May.

When asked if the two had the radio beacon aboard, the women told the AP on Friday they had a number of other communications devices, but they didn't mention the EPIRB.

The device communicates with satellites and sends locations to authorities. It's activated when it's submerged in water or turned on manually.

During the post-incident debriefing by the Coast Guard, Jennifer Appel, who was on the sailboat with Tasha Fuiava, was asked if she had the emergency beacon on board. Appel replied she did, and that it was properly registered.

"We asked why during this course of time did they not activate the EPIRB. She had stated they never felt like they were truly in distress, like in a 24-hour period they were going to die," said Coast Guard spokeswoman Petty Officer 2nd Class Tara Molle, who was on the call to the AP with Carr.

Carr also said the Coast Guard made radio contact with a vessel that identified itself as the Sea Nymph in June near Tahiti, and the captain said they were not in distress and expected to make land the next morning. That was after the women reportedly lost their engines and sustained damage to their rigging and mast.

Experts say some of the details of the women's story do not add up.

A retired Coast Guard officer who was responsible for search and rescue operations said that if the women used the emergency beacon, they would have been found.

"If the thing was operational and it was turned on, a signal should have been received very, very quickly that this vessel was in distress," Phillip R. Johnson said Monday in a telephone interview from Washington state.

Emergency Position Indication Radio Beacons, or EPIRBS, activate when they are submerged in water or turned on manually and send a location to rescuers within minutes.

The beacons are solid and built to be suddenly dropped in the ocean. "Failures are really rare," Johnson said, but added that old and weak batteries also could cause a unit not to work.

It's not clear if the pair had tested it before the journey.

The women also said they had six forms of communication that all went dead. "There's something wrong there," Johnson said.

He knows of cases in remote Alaska where a ship in distress just using one form of beacon brought a fairly quick response from nearby fishing boats and the Coast Guard.

"I've never heard of all that stuff going out at the same time," he said.

And there's more that doesn't add up.

Key elements of the women's account are contradicted by authorities, weather reports and the basic geography of the Pacific Ocean. The discrepancies raised questions about whether Appel and her sailing companion, Tasha Fuiava, remember the ordeal accurately or could have avoided disaster.

The Hawaii residents reported that their sailing equipment and engine failed and said they were close to giving up when the U.S. Navy rescued them last week, thousands of miles off course. They were taken to Japan, where they didn't immediately respond to an email and call seeking comment Monday.

The Navy said they do not investigate incidents like this and they were only there to render assistance. The Coast Guard said its review of the case is ongoing, but that there is no criminal investigation at this time.

The two women met in late 2016, and within a week of knowing each other decided to take the trip together. Fuiava had never sailed a day in her life. They planned to take 18 days to get to Tahiti, then travel the South Pacific and return to Hawaii in October.

On their first day at sea, May 3, the two U.S. women described running into a fearsome storm that tossed their vessel with 97 km/h winds and 9-metre seas for three days, but meteorologists say there was no severe weather anywhere along their route during that time.

After leaving "we got into a Force 11 storm, and it lasted for two nights and three days," Appel said of the storm they encountered off Oahu. In one of the first signs of trouble, she said she lost her cellphone overboard.

"We were empowered to know that we could withstand the forces of nature," Appel said. "The boat could withstand the forces of nature."

But the National Weather Service in Honolulu said no organized storm systems were in or near Hawaii on May 3 or in the days afterward. Archived NASA satellite images confirm there were no tropical storms around Hawaii that day.

The pair said they thought about turning back, but the islands of Maui and Lanai didn't have harbours deep enough to accommodate their sailboat. At 15 metres long, the vessel is relatively small, and both islands have harbours that would have accommodated them. Plus, the Big Island - the southernmost island in state - has several places to dock.

"I had no idea that we were going to be in this thing for 80 solid hours," Appel said of the storm of which there is no record.

Still, they pressed on.

Days later, after parts of their mast and rigging failed, they sailed up to another small island, still with a working motor, but decided against trying to land, believing the island was mostly uninhabited with no protected waters.

"It is uninhabited. They only have habitation on the northwest corner and their reef was too shallow for us to cross in order to get into the lagoon," Appel said.

But Christmas Island, part of the island nation of Kiribati, is home to more than 2,000 people and has a port that routinely welcomes huge commercial ships.

"We could probably nurse it down to the next major island in Kiribati," Appel said. Then we'll be able to stop there and seek safe haven and get up on the mast and fix it."

The island has at least two airfields, and women had flares aboard to alert people on land. Plus, its widest point spans about 48 kilometres, a day's hike to safety from even the most remote area.

When asked if the small island would have been a good place to land and repair their sails, Appel said no. "Kiribati, um, one whole half of the island is called shipwreck beach for a reason."

Christmas Island has a place called Bay of Wrecks on its northeast side.

So, instead of stopping for help, they say they set a new destination about 1,609 kilometres away and a few hundred miles beyond their original target of Tahiti. They were headed to the Cook Islands.

"We really did think we could make it to the next spot," Appel said.

Then, they say, another storm killed their engine at the end of May. More than five months after they departed, they were picked up in the western Pacific about 1,448 kilometres southeast of Japan and thousands of miles off course. The two women and their dogs were all in good health when picked up by the U.S. Navy.