KAILUA — Rescuers yesterday found the body of a California man who fell off a rented kayak after it was hit by a wave off Lanikai on Monday.

Colleagues identified the body as that of 49-year-old Johnny Yu, an Air Force reservist who was in Hawai'i with his unit for training, said Capt. Emmit Kane, spokesman for the Honolulu Fire Department. No official identification by the military or other authorities was given yesterday. An autopsy was scheduled to determine the cause of death.

Yu and a 26-year-old woman from the same Reserve unit rented a tandem kayak from Hawaiian Watersport on Monday morning, and were with a guide when a wave capsized their kayak as they returned from the Mokulua islets, Kane said.

The woman swam safely to the guide's kayak, and they returned to shore.

The woman said neither she nor Yu were wearing life jackets when the accident occurred, according to Kane. Yu's body was found within 150 yards of where he was last seen, near reefs on the Kane 'ohe side of the Mokuluas, Kane said. There was no life jacket on the body, which was 15 to 20 feet below the surface, Kane said.

Kane couldn't say if a personal flotation device would have saved the man's life, but said history shows that wearing them helps people survive.

"The water environment is very unforgiving," Kane said. "PFDs (personal flotation devices) are always a good idea."

The vests are designed to turn people face up, and that keeps airways open in case of an injury that renders a person unconscious, he said.

Coast Guard Petty Officer Michael De Nyse said vessels such as the rented kayak are required to have life vests aboard. He said children 13 and younger are required to wear them. For people 14 and older, wearing the life vest is discretionary, but people are urged to do so, he said.

"We strongly recommend that everyone aboard such a vessel wear a life jacket," De Nyse said yesterday.

Hawaiian Watersports would not discuss its rules for wearing life jackets, but said it follows the same procedures as other kayak rental companies.

Kailua Sailboards & Kayak owner Egmar Klemmer said he absolutely requires his customers to wear Coast Guard-approved flotation devices when they are accompanied by a guide. Klemmer also said that the area where the body was found is off limits to his renters. He said his company considered it too dangerous to go past the reef into the heavy waves.

"I can tell you none of our guides would go where they went," he said.

Kane said rescue teams returned to Lanikai at daybreak yesterday. That included the HFD Air One helicopter, and rescue specialists from Bellows Air Force Station.

A Bellows rescuer found the body in a crevice in a reef at about 11:45 a.m., Kane said.

The rescuer was being towed by a powered watercraft over the search area when he spotted the body. Using scuba gear, he was able to pull the body through a hole in the reef and bring it to the surface, where it was taken to the Kailua Beach Park boat ramp, Kane said, adding that a colleague identified Yu's body at the boat ramp.

Local Air Force officials deferred questions to Travis Air Force Base, Calif., where the reservist's unit operates from. No comment was available.

Kane said the man's wife has been notified.

Reach Eloise Aguiar at eaguiar@honoluluadvertiser.com.