"Finally at 4am, a gust blew out the sail and torn fabric filled the air with a swooshing sound.
"It was dark and there was nothing I could do but watch the sail self-destruct."
At dawn, he began the long process of getting the sail down and on deck before stuffing it away below.
It was a task too dangerous to do at night, he said.
While pulling on pieces of sail stuck in the shrouds, a piece suddenly gave way and Dr Paris fell flat on his back on to a stainless steel dorade - a small box-shaped extrusion on the deck.
"The pain just below my left scapula was as much as any pain I have ever experienced.
"I lay still for a few minutes testing my lungs and then started to get going.
"I could feel a rib cracking in my back.
"Crawling was out [of the question] as my left arm could take no weight.
"A few more actions and I collapsed for several hours in the cockpit."
Yesterday, he said he was feeling better but was very limited with what he could do with his left arm.
"It's getting better and will take a few more days before some of the needed tasks on the boat can be attended to."
He is now about a third of the way between South America and South Africa, and said he was sailing "conservatively and gently" until such time as he was ready for the full rigour of daily duties again.
"I shall be fine - I just need to take it easy as best I can for now."
His son Alan said he had been in touch with Dr Paris, and believed based on his description of the pain, he had "fairly significantly" damaged his ribs where they connect with the spine.
Mr Paris said his father had no lung capacity issues or blood in the lungs, so he believed he was probably past the worst of it.
"He's a tough old Kiwi bugger."
Dr Paris left St Augustine on the east coast of the United States on December 3 in his purpose-built yacht Kiwi Spirit, and his official record attempt began in the northern hemisphere, near Bermuda on December 7.
Once he reaches South Africa, he will sail through the Southern Ocean past Australia, New Zealand and South America, before heading back to Bermuda.
He hopes to do it all within 120 days, which will be 30 days quicker than the late Dodge Morgan's solo Bermuda-to-Bermuda record, set in 1986.