A re-energized Poulter relished the links test, making three birdies in his first seven holes before battling the worst weather of the week on his back nine to shoot a 1-under 71.
"It was a job just to hold the umbrella," said Poulter, who is hitting top form a week before playing the British Open at Royal Birkdale, where he was tied for second the last time it was staged there in 2008.
"There's life in the old dog yet," Poulter added, with a determined smile, "and I'm relishing the opportunity tomorrow to go out and get stuck in."
The last of Poulter's 14 global victories was in November 2012 at the WGC-HSBC Champions in China.
The Scottish Open is seen as an ideal tune-up for the British Open. Players probably could have done without conditions like they were on Saturday, though.
The tee times were brought forward by about three hours because of high winds forecast for late afternoon. The bad weather arrived a few hours earlier than expected, just when Poulter and the other lead groups were coming in.
"No. 12 was about as tough as I've ever seen in terms of wind and rain," Poulter said, holding a cup of tea to warm his hands.
American player Matt Kuchar said a 6-iron went 127 yards.
"I was out there thinking what my friends back home would be doing," said the Florida-born Kuchar, who shot 73 and was four shots off the lead.
Fellow American Rickie Fowler struggled to read the greens and was off line with his wedges in shooting 74. He was level with Kuchar, who dueled with Fowler for the Scottish Open title at Gullane in 2015. Fowler won with a birdie at the last.
Padraig Harrington, who has a reputation as a good player in bad weather, struggled more than most. Starting in a share of the lead, Harrington missed two-footers for par on Nos. 1 and 4 and had six bogeys and double in a 79, which dropped him to a tie for 23rd.
Poulter, known best for his Ryder Cup exploits with the European team, is playing with "pressure off my shoulders," three months after thinking he'd lost his U.S. PGA Tour card.
He played just 13 tournaments in 2016 because of a foot injury and didn't earn enough FedEx Cup points or money in early 2017 to remain fully exempt. When Brian Gay alerted officials to a discrepancy in the points structure used for players competing with a medical exemption, Poulter got a reprieve.
"There's no question I feel better because of that," Poulter said. "I can just go out and play golf."
On a day when pars felt like birdies, Poulter was delighted to just make one bogey on his back nine.
"You can beat yourself up before you get on the golf course," he said. "You know it's going to be tough. You know it's links golf."
Shinkwin and Dodt are in a good position to claim two of the three Open places available for non-exempt players who finish in the top 10.
Dodt is due to fly to New York with his wife, Ashleigh, on Monday for a holiday. Those plans might have to be scrapped if he makes it to Birkdale for his first major.
Shinkwin, the world No. 405, has had more disqualifications (two) than top-25 finishes on the European Tour this season. A tap-in eagle putt on No. 14 came between two birdies on a fighting back nine.
"I don't think I've played in wind and rain like that before," he said.
