The father of a novice boatie who died in the cold waters of a Southland lake pleaded for a licensing system for people who own or are in charge of boats.
Jason Bradley Burford died on August 25, 2014, aged 19, when the boat he and two friends had taken out onto North Mavora Lake sank.
His two friends made it to shore, but he died in the cold water.
Coroner Richard McElrea released his findings after an inquest into Mr Burford's death.
Mr Burford had only recently acquired the boat and had no prior experience with boating, the coroner said.
He had taken the 4.42m home-built fibreglass recreational boat out on to the lake about mid-morning for some fishing with his friends.
The boat was powered by a 115 horsepower outboard motor, but the motor not had not started that morning so the group attached a 25 horsepower auxiliary motor to the rear of the boat.
The motor was too powerful for the boat and came away from the bracket, leaving a hole in the boat.
The boat filled with water quickly and sank.
Mr Burford was wearing a lifejacket when the boat began to sink, and his two friends had time to put on a lifejacket before they entered the water, which was about 7C.
They began swimming to the nearest shore about 600m away.
A passer-by heard shouting from the lake and could see "dots in the water". She had to drive 30km to get cellphone reception and call 111.
Mr Burford's body was recovered from the lake at 5pm, after search and rescue personnel found the two friends on the shore.
Coroner McElrea concluded that the auxiliary motor was too big, in terms of weight and power, for the boat and the bracket it was attached to.
Mr Burford's father Leigh Burford made a plea for a licensing system for persons who own or are in charge of boats; a requirement for a warrant of fitness for boats or watercraft to demonstrate seaworthiness; and for any modifications such as heavier more powerful engines to be certified.
Bruce Derek McLaren, senior specialist maritime officer at Maritime New Zealand said recommendations like Leigh Burford's were frequently asked in circumstances like this, but they did not reflect the current views of Maritime New Zealand or of the wider recreational community.
He said that the primary safety learning arising out of this death was that it was essential for owners and skippers to ensure their vessels were properly maintained and suitable for the activity being undertaken.