With inclement weather forecast in New Plymouth for Sunday, two rounds will be played on Saturday to ensure the tournament is completed as a 72-hole strokeplay event.
"It is going to be a challenge playing 36 holes in a day and I am sure the guys are going to attack my lead," Ratcliffe said. "I just have to keep doing what I am doing. It has got me this far and if I play my natural game then I will be attacking."
Jim Cusdin's round was the talking point. The Waikato professional, who is aiming to win consecutive Charles Tour titles, was five over after his first nine holes and then came home with a sparkling seven-under 29, including a hole in one, to post the then-clubhouse lead at seven under.
"It was unreal golf," said the 26-year-old. "I was in a bad position after making some really stupid mistakes on my front nine and I was ropable so I stopped and had a few words with myself. The first goal was to get back to even par but it ended up being a ridiculous round of golf where everything started going in.
"The best thing is that the back nine has got me back in contention, I was getting pretty down on myself but it is a good feeling to walk off the course with a two under par. That has to be one of the best recoveries I have ever had. It is a special feeling.
"I have given myself a chance, now it is a matter of not getting ahead of myself and staying patient out there. Today shows that anything can happen and you should never give up."
Defending champion Troy Ropiha was disappointed with his two-under-par 70 that got him to six under for the tournament and five shots back from the lead.
Waikato professional Mark Purser, a two time winner on the Charles Tour, had a second successive three under 69 to also be five shots back.
Dominic Barson had a four under par 68 to get to five under for the tournament and within striking distance.
In the women's field, Waikato Emily Perry continued her resurgence, with a four-under-par 68 to establish a four-shot lead over professional Charlotte Thomas at the halfway stage.
The New Zealand representative made four birdies, a double bogey and an eagle as she chases back-to-back Charles Tour titles.