The voyaging canoe was to sail from Tern Island before dawn today, after an emergency return to the island on Saturday. The canoe will continue its mission of sailing through the Northwestern Hawaiian Islands.

Thompson will remain aboard because a team of Honolulu physicians agreed by telephone with the canoe crew's doctor, Cherie Shehata, that he would be safer on his beloved twin-hulled vessel than aboard a small unpressurized aircraft — the only kind that can fly into the 3,000-foot coral strip at Tern.

The veteran sailor, non-instrument navigator and chairman of the Kamehameha Schools board of trustees suffered a back injury Saturday afternoon when he was thrown against the end of a thick wooden railing as he worked at the front of the port hull.

He said it was the first injury he has ever suffered aboard the canoe.

Shehata, speaking about Thompson's condition with his approval, said the injury initially appeared to be a severe bruise with a possible fractured rib or ribs. That is a special concern because a broken rib could puncture a lung, and Thompson only has one. The other lung was removed years ago because of injury.

"If it's fractured and it gets hit again, it could puncture the lung, and I don't have another one. I'm a liability on board," he said yesterday morning.

After Thompson was brought to Tern Island by a Fish and Wildlife Service boat yesterday, Shehata said four Honolulu physicians who reviewed the navigator's condition agreed that a significant lung puncture would have presented specific symptoms by that time, and such symptoms were not present.

But there was risk. Doctors said there might be a minor lung injury, and an unpressurized flight could cause more problems. The doctors said Thompson was better off on the canoe, as long as he was protected from possible further injury by resting and not being allowed to do physical work.

He can still navigate.

And by the time the canoe reaches Midway on June 9, he should be well enough to fly.

After Thompson was injured, Shehata ordered the canoe to return to Tern, where evacuation and other options would be available sooner than if the canoe proceeded the several hundred miles to the next island with an airfield, Midway.

Hokule'a was 60 miles northwest of French Frigate Shoals, which it had left Saturday morning. Canoe sailing master Bruce Blankenfeld, Thompson's brother-in-law, held a crew meeting at about sunset and reviewed what was known about Thompson's condition. He said the canoe would be towed by escort vessel Kama Hele, because it would take too long to sail into the wind to reach Tern.

"This is something that we're prepared for, something we plan for," he said.

It was already dark. The crew quickly prepared a tow line. Two large orange buoys were attached to the end of the tow line, and glow sticks were tied to the line every 12 feet, so that the escort boat could see the lay of the line.

Then the tow line was fed overboard and allowed to drift away from the canoe. The Kama Hele approached the lighted line and hauled it aboard with a boat hook. Shortly, Hokule'a was being pulled toward French Frigate Shoals at about 5 miles an hour.

Thompson was walking around the canoe, although gingerly and clearly in some pain.

Shehata immediately began contacting other doctors by satellite phone. She also called the crew's insurance carrier, Divers Alert Network; the Fish and Wildlife Service, which operates a wildlife station at French Frigate Shoals; the Coast Guard; and Thompson's family. Hokule'a was towed through the night, arriving at the French Frigate Shoals mooring at 11 a.m. yesterday.

After the decision was made for him to stay aboard, Thompson met with escort boat captain Tim Gilliom, Blankenfeld, Shehata and other crew members on Tern, and outlined a revised trip up the chain. They were expecting to arrive at Laysan Island Wednesday morning and end up at Midway by June 9.

Thompson said he regretted having to turn the canoe around, but felt he had to concur with the physician's decision.

"We as an organization by principle say safety is first. We bring a doctor on board as a resource, a specialist necessary to keep the voyage as safe as possible. To compromise that level of safety is simply not acceptable," he said.

Shehata said a well-developed emergency plan helped the process.

"It went smoother than I thought it would. Everyone organized themselves. Those who knew about the radio box gathered around it. ... People set about steering the canoe," she said.

The canoe carries extensive medical supplies in two large coolers and a large dry bag.

"It's like an outpatient clinic. I have antibiotics, pain medication, sutures, seasickness medicines, things to deal with colds, infections, sprains, casting material for bone breaks," she said.

Blankenfeld said the canoe has dealt with all kinds of medical conditions, including broken bones, cuts needing stitches, severe infection, people knocked unconscious. For medical problems and every other issue that might occur, the Polynesian Voyaging Society has tried to develop procedures, he said.

"There are procedures for every emergency down the line," Blankenfeld said. "Here we are, implementing the procedures."