Gerhard Wagner, 61, was last seen riding his motorbike on January 7, 1999 - after working on his beloved twin-masted 42-foot yacht at a Brisbane marina.

Neither his body nor the motorcycle has been found.

On Wednesday in the Brisbane Supreme Court, Gerhard's younger brother, Paul Kinter Wagner, said the boat was transferred to Robert James Wagner, 57, for "safe-keeping".

"He broke up with his girlfriend and he thought she might claim the boat because she helped him (paint it)," he said.

"He didn't want to lose any part of the boat (so) he put it in Robert's name."

Wagner is accused of killing Gerhard in the garage at his Brisbane home.

He denies it.

On Tuesday, a witness, who can't be identified for legal reasons, told the court Wagner confessed to him it was a premeditated killing about money.

He said Wagner used an axe, a hammer and a knife to murder and "chop up" Gerhard.

Wagner then took "skin and the guts" to a Brisbane river, he said.

The rest of the body was buried at Mount Tibrogargan in the Glass House Mountains National Park, north of Brisbane, he said.

The court has also heard Wagner, who was the executor for Gerhard's will, had also made changes to it in the months before his uncle's disappearance.

On Wednesday, Paul Wagner spoke lovingly about his brother, but said he lacked a solid understanding of financial matters.

"He was free and open about financial affairs. He didn't mind discussing it with anyone," he said.

The court heard Gerhard Wagner also worried his brother may not approve of who he had decided to leave his wealth to.

"He said my current will is such that in the event of my demise, Robert gets gifted the $300,000 he owes me," Paul Wagner said

The trial continues on Thursday.

Australian Associated Press