He had been preparing, as had everyone else living in the barracks, for the morning routine inspection when a call came in about the Wahine ferry in trouble.
"About 9 or 10 o'clock we were told by our instructor… to get our rain gear, warm gear and boots.. So we did all that," he says. "We were loaded onto a bus and we were driven to Eastbourne. No one knew anything [about] what was happening."
He could still remember the horrific conditions they were confronted with.
They got to a farmer's gate which he remembers had been pried open by Lower Hutt police officers who'd got there a short while earlier.
He says they hiked for about a mile or two through muddy slips to catch up with them.
"We were walking along and the wind was pounding at us. You couldn't even talk without turning away from the direction it was coming in," he says.
"The seas were so high.. I'm not exaggerating when I say they were 20 or 30 feet high in the harbour."
Blackie says he remembers seeing the ferry out in the harbour but being unable to see through to the other side of the harbour due to the mist.
He says there were about 30 to 40 locals from the area who had come down to help.
"They really dug in.. I can't remember anyone ever sort of congratulating them for doing a good job. I don't know how we would've managed without those guys."
He remembers seeing people's heads bobbing in the water, and one officer in particular, Constable Joyce, who he'd met once before, lying on the pebble beach.
"He was absolutely soaked. He was missing his raincoat, his tunic, his helmet. He was shivering there, he was laying on the ground... Obviously suffering from exposure."
Blackie says he saw some of the volunteers in the sea, pulling some of the bodies out.
Some of the survivors couldn't walk, he says.
Blackie also remembers the dead, mostly elderly, being loaded onto a grey Land Rover.
He says he can't shake the image of the survivors wearing life jackets.
"It was the one thing that struck me about the whole thing. They were safe on land and none of them threw off their life jackets. They wore them right out to the gate. It was unbelievable," he says.
"Some of the women were in dresses... some guys were in suits. They were taking a ferry ride. No one was expecting this. They certainly weren't dressed for what happened to them."
Blackie has never spoken about his experience - not to his colleagues or even his two sons.
"I've thought about this probably on and off for 50 years and I think.. in my opinion, I was amazed the casualties were so low. Given the horrific conditions and the wind and the beating of those waves, I don't know how any of them survived," he says.
"It was amazing… It should've been ...at least 100.. 150 people dead."
Blackie went on to work in the police until 1973, before moving overseas to work in the United Kingdom and then on to Canada, where he's lived since.