Mark Mulcare is totally blind. He's also a three-time world champion helmsman.
The ability to see might seem essential when steering a yacht - and Mulcare can't operate totally on his own - but the Aucklander sails largely on feel.
"I work off how the boat feels and how it seems to be going through the water," he says. "I can gauge the heel of the boat and sense what the breeze is doing."
It's an innate ability that has served him well, winning three world titles, and he will chase his fourth when the blind sailing world championships get under way on Lake Michigan in the United States on Tuesday NZ time. Competition starts Wednesday.
Blind sailors are graded on their sight: B1 sailors are totally blind, those categorised B2 have some light perception and B3 individuals have about half the vision needed to be able to obtain a driver's licence.
Mulcare is B1. He lost his sight totally in his early 20s through a degenerative condition so has some understanding of colour and remembers family holidays as a child in the Bay of Islands when he fell in love with boats.
He "just decided to buy a boat one day" and soon got involved with racing.
"It was pretty easy to get involved. You basically bought a boat and went sailing. A few say, 'that's interesting' when I tell them what I do for fun but, overall, there's very little resistance to the idea of blind sailing."
Mulcare needs one sighted person on board and he and his brother Kevin have completed a number of two-handed races together as well as the Coastal Classic.
Kevin was on board for Mark's three world titles but will be missing this time around, with Tony Holmes, Terry Valder and David Steffensen travelling to Wisconsin.
There are strict rules on what each individual can do. Holmes is also totally blind and will operate the mainsheet, Valder is tactician but not allowed to do anything but talk and Steffensen is crew but can't steer the boat or trim the main.
Things can get a little hairy from time to time but not any more than with fully-sighted sailors - Emirates Team New Zealand were less than impressed when Ben Ainslie gave them a "love tap" in practice racing ahead of the America's Cup and bumps are commonplace in fleet racing at all levels.
"I haven't had any prangs," Mulcare says, "at least nothing serious. Just the bumps that happen.
"You can sense when other boats are around, and there's plenty of advice coming off other boats. It can be a bit nerve-racking, especially going around the marks, and it makes me grow old."
Mulcare has missed the past few world championships - his last world title was in 1999 - but he finally succumbed to the harassment of fellow sailors to compete again.
"I'm pleased I did," he says. "I've got the itch back again."
They will be the only New Zealand team competing in Lake Michigan and have been training on the 7m Sonar yacht Rick Dodson, Chris Sharp and Andrew May used at last year's Rio Paralympics.
"I've been out of it too long to have a really good handle on how everyone goes. But I like how our preparation has gone so far. It's not been perfect but there have been a few positive signs.
"We'll know where we stand in the next couple of weeks."