Since he pulled 13 survivors out of the water near Tofino, B.C., on Sunday, Ken Brown has thought a lot about what would have happened, if he hadn't seen the flare from a whale-watching boat in trouble.

Brown and his partner, Clarence Smith, were fishing grounds they had never fished, facing Vargas Island off Tofino.

As they were pulling in their halibut longline, Brown happened to turn around, and saw in the sky a single flare — the only signal anyone could see from the capsized wreckage of the MV Leviathan II, which flipped so quickly there was no time to send a mayday call.

"I knew what it was right away. I knew people were in distress and somebody needed help," said Brown, an Ahousaht fisherman.

He yelled to Smith, who saw the rocket flare falling, and the pair pulled in some 200 metres of fishing line to scramble to the scene.

The TSB revealed Tuesday at a news conference that two hand flares and a rocket flare were sent from the vessel before it sank.

'Get this lady out of the water — she's pregnant'

What Brown didn't know was the scale of the emergency. At first, the triangle shape on the horizon looked like a sailboat, grounded on a reef.

MV Leviathan submerged Albert Titian

This photograph of the MV Leviathan II was shot by Albert Titian as Ahousaht First Nation boats scrambled to help those forced into the water by the sinking ship. (Albert Titian/Facebook)

As they got closer, five or 10 minutes after seeing the flare, the pair realized what they were seeing was the bow of the 20-metre Leviathan, one of the biggest tourist vessels in the area.

"There was people screaming, you could hear a lady screaming on the rocks," said Brown.

Three people waved from an inflatable emergency raft that bobbed in the water, one waving a paddle in the air, as waves continued to crash.

As they reached yelling distance, those on the raft screamed to the rescuers to help people still stuck on the wreck.

"Go help them! There's people, they need your help!" Brown remembers them saying.

One man, his ankle wrapped in green fishing line that was dragging him into the water, was "hanging on for dear life" to the vessel, he said.

Brown and Smith threw the man a float, and grabbed his belt buckle to heave him on board. They then cut him free from the line.

"If we didn't get that guy, that line that was wrapped around his ankle, he wouldn't have been able to free himself from that boat. I said I don't think that guy would have made it."

Two women were swimming between the capsized boat and the life-raft, and the one with a life-jacket told them to help the other woman first.

"She said 'this lady is pregnant and my leg is broken, but I want you to get this lady out of the water — she's pregnant.'"

21 survivors rescued

Ten others piled onto Brown's boat from the emergency raft, making 13 soaking survivors on the six-metre fishing vessel.

By then, larger boats responding to the fishermen's distress call had arrived to help rescue a total of 21 survivors, and pull the bodies of five people from the water.

Brown and Smith covered the quiet, shivering people with every piece of clothing they had on their vessel.

He's thankful his partner "twisted his arm" to fish that area, that day.

And that he turned around, at the very moment the single flare — scrounged from that emergency raft — was in the sky.

Does he think about what might have happened, if he hadn't?

"Yeah, I had all night to think about it," he responded.

With files from Skye Ryan and All Points West