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– When the Conception first hit the water in the early 1980s, the personal electronics revolution was decades away.

Divers who boarded the 75-foot boat for excursions in the Channel Islands brought film cameras. There were no smartphones to plug in, or other electronic devices.

But when the vessel set off decades later on its fateful Labor Day voyage, those on board needed power — a lot of it. And they plugged their equipment into a series of outlets concealed in the back of foam-filled L-shaped benches in the ship's galley.

Those outlets are now the focus of an intense investigation as federal officials try to determine the cause of the worst maritime disaster in modern California history, a fire that swept through the dive boat and killed 34 people.

The Conception was raised from the depths of Platts Harbor and is now at the Port Hueneme naval facility, where the Bureau of Alcohol, Tobacco, Firearms and Explosives' national incident team of leading fire experts is examining the power, fuel and electrical systems, federal officials said.

As the investigation continues, the U.S. Coast Guard took the unprecedented step of recommending that owners of passenger vessels immediately urge crews to "reduce potential fire hazards and consider limiting the unsupervised charging of lithium-ion batteries and extensive use of power strips and extension cords."

Divers and others in the boat world said the electrical systems of boats such as the Conception have been put to the test in recent years as the number of electronics brought on board has increased.

Competing for limited plug space are batteries for strobe lights, digital cameras and underwater light rigs, video camera power packs, GoPro chargers and lithium-ion batteries for phones and tablets.

"People have rechargeable everything these days," said veteran diver Ben Wolfe, a retired fire captain who dived off the Conception two weeks before its fiery demise. "I had a battery like a TV camera battery that powered my underwater scooter plugged in each night."

Preliminary investigation has suggested the fire did not start in the engine room, and there are growing signs the origin was in the galley area. On the morning of the fire, one crew member told a rescuer he thought the fire started with electronic devices charging in the galley.

One of the crew members, Ryan Sims, has filed a lawsuit against the Conception's owners, alleging that Truth Aquatics Inc., Worldwide Diving Adventures and boat owner Glen Fritzler failed to properly train crew members, give adequate safety or medical equipment and provide safety rules.

Sims said in court filings that he was awakened by loud noises to discover the already raging fire. He jumped from the top deck, where he had been sleeping, and broke his leg, before joining four other crew members in a dinghy they took to a nearby boat to call for help.

Some of the crew returned to the Conception, but the boat was engulfed in flames and no one else aboard, including another crew member, could be saved.

Statistics gathered by insurers and industry watchdogs show that about 55% of shipboard fires in small vessels are related to electrical systems.