The pair had left Sumner and paddled to the Lyttelton Heads area where they fished for a while before deciding to paddle back.
But the wind had changed and they were unable to make headway in heavier seas. They capsized a couple of times and lost a paddle.
"They then decided that the safest option for them was to head over to the nearby rocks and to make landfall there and wait for the weather to change, which of course it didn't," Mr Penrose said.
He said the pair had been equipped for a shorter trip and the one they made may have been beyond their fitness levels and experience.
A communication device would also have been useful. "They have been well-informed of that. They also needed to make better intentions with their relatives because this was reported quite late at night which made our search much harder," Mr Penrose said.