As the boat sailed eastward, David Aalhus spotted the whale about 30 metres ahead, its nose pointed toward them. A minute later, the boat shuddered and nearly lifted out of the water.

The banging sound from below was Luna playing with the rudder.

For four hours, Mr. Aalhus and his son tried everything to lose the whale, but it was having too much fun. “It was like he was playing with us, like we were toys, like he didn’t know his own strength,” David, 38, said.

When the whale wasn’t underneath the boat, it splashed alongside it, looking eerily human.

“What kind of a whale interacts with boats and humans?” David asked. “You should have seen him lying beside our boat, looking up at you with his eyes, like he wants you to pet him.”

Luna’s knocks against the rudder disabled the steering. Eventually, a packer heard Mr. Aalhus’s distress calls and towed the Wendy-Lynn to a nearby bay, where the two men spent the day repairing the steering.

That afternoon, they sailed north to a fishing ground in Tlupana Inlet, more than 10 kilometres from where they last encountered Luna. As they slowed their boat, Mr. Aalhus’s heart sank as the whale’s distinctive outline appeared on the horizon. Luna was back for Round 2.

This time, Luna pushed the rudder loose and turned it around so that it hit the boat’s propeller blades, disabling the Wendy-Lynn. Luna was pushing the boat toward a rocky beach. Mr. Aalhus went to work on the rudder with a pipe wrench. At that moment, Luna rammed the broken rudder again, pinning Mr. Aalhus to a fuel tank with the wrench.