They paddled across to where the boat was moored but Amie lost her grip on the board and was pulled towards the side of the boat before going underwater.
Her board was swept to one side of the boat while she was stuck under the boat on the other side unable to free herself, likely due to her leg rope becoming wrapped around the boat's keel.
In his report Mr Matenga said: "The force of the current was pushing both Amie and the [stand-up paddleboard] in the same direction. With Clara's keel as an underwater obstruction, Amie was effectively trapped under water. The pressure of the current and the tension created by the rope made it impossible for her to release the ankle strap."
By the time others managed to free her and get her to the surface she was unresponsive.
Mr Matenga found that the leash, which Amie attached to her ankle to keep the board close because of the current and boat wakes, contributed to her death.
"This style of leash is not recommended to be used in fast-flowing water due to the risk of the leash being caught on an obstacle and the paddler not being able to release the leash because of the strength of the current, as happened in this case. The quick-release leash, a leash which attaches to a quick-release strap around the paddlers waist, is recommended for use in white water, rivers and bodies of water which have a strong current ... the release mechanism is usually at waist level and so more easily accessible to the paddler.
"If Amie were using the quick release it is most likely that she would have survived."
Mr Matenga also recommended appropriately placed signage around the harbour which was targeted at stand-up paddleboarders and warned of "the dangers of the fast flowing current in the harbour and the need to be cautious concerning unseen obstacles, especially around moored boats" but he acknowledged the limitations of this. He also recommended stand-up paddleboarders use a personal flotation device "appropriate for their activity".
Amie was wearing a bum bag style lifebelt which must be unzipped and pulled over the head before it is inflated by pulling a cord.
Mr Matenga found the type of lifejacket worn by Amie would not have changed the outcome for her but warned others there may not be time to unzip a lifebelt, put it on and inflate it if you were to get into trouble while paddleboarding.
