He said the kayaker was struggling just to stay upright and not capsize, as the conditions worsened.
Henshaw praised the kayaker's preparedness, saying it was "a tremendous example of how being prepared can save your life."
"In addition to the distress beacon, the kayaker was well kitted out with life jacket, VHF radio and a red smoke flare," Henshaw said.
"Being well equipped can really take the search out of search and rescue."
Four other vessels in the area, including the Interislander ferry Kaitaki, offered assistance after the alarm was raised.
Passengers on board the Picton-bound ferry from Wellington faced a short detour as the Kaitaki turned back and offered to help.
The kayaker and his gear were transferred to the police-launched Lady Elizabeth IV and he was given a ride home, to Wellington.