British Open champion Brian Harman says he will celebrate his first major win at Hoylake by jumping on his new tractor, joking that he is a man of many layers "like an onion".

The 36-year-old American returned a score of one under par in his final round on Sunday for a 13-under total, finishing six strokes clear of the chasing pack.

As the rain lashed the Royal Liverpool course, Harman, a passionate bow-and-arrow hunter, plotted some down time back in the United States.

"I had a nice week a couple weeks ago and I bought a new tractor for my hunting place, so I'll get home and I'll be on the tractor mowing grass in the next few weeks, so I'm excited about that," he said.

"Just put my phone away and go get on the tractor."

Harman said he had not yet told his wife how much his new orange Kubota machine cost -- but he certainly has his work cut out.

"We've got about 25 acres of food plots that need, and, gosh, I don't know how many miles of roads, but I'd call it probably 40 acres total that needs to get mowed," he said.

A reporter said he had never known an Open champion celebrate by mowing grass on a tractor.

"I've got a lot of layers, man," he replied. "I'm like an onion."

Harman, ranked 26th in the world, has previously won just two events on the PGA Tour, though he finished tied for second at the 2017 US Open.

He described the soaking wet conditions at the course on England's northwest coast on Sunday as "Armageddon".

"It was bad, it was really tough," he said. "I haven't historically done very good in the rain. It's just always bugged me. I was really proud of the way that I struck the ball in the rain today."

Despite his generally solid performance, Harman said he had "fleeting" doubts during his final round, though he tried not to let them into his head.

"I really honestly didn't think about winning until I had the ball on the green on 18," he added.

"I've always had a self-belief that I could do something like this. It's just when it takes so much time it's hard not to let your mind falter, like maybe I'm not winning again.

"I'm 36 years old. The game is getting younger. All these young guys coming out hit it a mile and they're all ready to win. Like when is it going to be my turn again? It's been hard to deal with."