"It was an obviously deliberate act but not with a great deal of planning."
A probation report said Ray, who was diagnosed with depression and schizophrenia, had a high risk of re-offending.
Ray and Mr Kaipara, who were related through Ray's adoptive mother, had been drinking heavily and fighting with each other during the day leading up to the murder, Justice Venning said.
The fighting between the men had become serious leaving Ray temporarily unconscious and with a broken leg, before they both went inside to eat dinner with Ray's biological mother and 9-year-old nephew.
During the meal Ray moved behind Mr Kaipara and grabbed a carving knife from the bench.
He began to sharpen the knife before plunging it through Mr Kaipara's neck up to the hilt, extending the point of the blade on the other side, cutting his voice box and jugular.
As Mr Kaipara lay on the floor Ray continued to yell at him and stopped his mother from helping.
"Although you said afterwards you never intended to murder Mr Kaipara you must have known that a stabbing in this manner would kill someone," Justice Venning said.
Crown prosecutor Heidi Wrigley said the murder was highly deliberate and premeditated, and happened in front of a 9-year-old boy who had regarded Ray as a role model.
