Oli is an "ordinary" moggie, a mate and now a cat with a Sydney to Hobart yacht race to his name.

Owner Bob Williams and his feline friend completed the 628-nautical-mile bluewater event on Wednesday morning on board Sylph VI alongside co-skipper Chris Warren.

The trio were the last of 85 finishers, with a time of seven days, 19 hours, 26 minutes and 15 seconds.

Their arrival at Hobart's Constitution Dock was met with cheers and supportive signs, as well as cat treats and toys from loved ones and casual observers gripped by Oli's tale.

Williams, who has sailed with 10-year-old Oli for about five years, was emotional.

"I am just a bit. I don't know why. I think it's the cat," he said.

"It's quite amazing how people have taken a shine to Oli. It is not something I expected.

"For me, Oli is part of my crew, part of the boat.

"He's become quite an international celebrity apparently. He's just an ordinary little moggie, my friend and mate."

It was a first Sydney to Hobart for Williams and the 10th for Warren, who celebrated crossing the finish line on his birthday.

Warren said Oli was very comfortable in the open water, had strong sea legs and came up onto deck as the River Derwent end neared.

"He just tucks downstairs and jumps in the bunk. He's spent half his life on the boat," Warren said.

"Every time Bob is in the bunk he just jumps straight up and cuddles up (with him)."

Warren said the sailing was "pretty tough going" with seas of four-to-six metres in Bass Strait when a gale passed through.

There was also light air and headwinds which slowed their progress.

It appears Oli was not the first of his kind to feature in the Sydney to Hobart, with a media report pointing to a cat being on a yacht in 1947.

Williams has sailed Sylph VI, the oldest boat in the 2023 race, around the world two-and-a-half times since buying her in 1997.

He had finished a non-stop solo circumnavigation last year when his sister's suggestion of a Sydney to Hobart attempt piqued his interest.

"(The race) means a lot to most Australians - most Australians know about it," he said.

"For sailors, it's something you've got to do if you can.

"Not everyone is privileged enough to have that opportunity. I am very privileged to have this old boat."

Williams said he and Oli would explore Tasmania's waterways over the coming days.

"I wasn't expecting this much attention," he said.

Supermaxi LawConnect took out line honours for the race on December 28 in a nail-biting finish, while Alive was crowned handicap winner for the second time.