It got through three waves before being capsized by a fourth.
The pair swam for about half an hour towards the north side of the river mouth.
When Mr Tutauha last saw Mr Symonds, he was about 15 m from shore and indicated he was okay.
But next time he looked Mr Symonds has disappeared and was later spotted 30m out to sea.
With the help of others Mr Tutauha managed to drag Mr Symonds ashore where CPR was performed. But he did not recover.
In Coroner Tim Scott's decision released this week he said the sea conditions were too rough for the relatively small boat.
"Probably because of relative inexperience (Mr Symonds) made a significant error if judgment in attempting to cross the Patea River bar when he did," Coroner Scott said.
"The two men however were wearing life jackets and accordingly they had a reasonable chance of survival even though the boat capsized on the river bar.
"It is not possible for me to determine exactly why (Mr Symonds) was unable to reach the shore although he had apparently given (Mr Tutauha) the thumbs up or an all is well signal when he was very close to it."
Coroner Scott made no recommendations and said nothing more could have been done to rescue Mr Symonds.
But he said "river bars especially on the west coast of New Zealand are inherently dangerous.
"A great caution is needs to be exercised when crossing them particularly if in a small boat and if relatively inexperienced in boat handling."