Coley had a heavy crash during his first qualifying run of the day but managed to get the boat running again.
By the time the finals began, the sun was so low the reflection off the water was causing the crews headaches.
Drivers started gauging where the turns were by the sight of the reeds on the water's edge, while taking pot-luck as they gunned it for the visible one out of the two course-end flags that they were heading into the finishing bay and not the wall.
Minnell described it as the hardest racing he had been involved in.
"The track was very dangerous, lots of spills," he said.
"It was 'he who had the biggest nuts'."
In the final eliminator Caughey clipped a few banks and lost valuable time, whereas the Minnells drove smoothly to finish in 50.236, beating the Cantabrian by 0.601 of a second to take their first win of the season.
Like Shelter View, Minnell held back during the day with modest 51-second drives before pouring it on from the Top Five eliminator onwards.
Former Wanganui driver Steve Bron, now based in Feilding, took third place with a 52.928.
Current Australian Superboat champion Greg "Crusty" Mercier had mechanical problems and didn't get into his stride.
Hamilton's Sam Newdick and Glen Mason won their second final in a row in PSP Group A with a 53.65 time using the reeds as a guide when they couldn't see the corners.
Aussie Paul Gaston came home narrowly in second place (53.91), with Wanganui's Richard Murray literally putting across the finish line with a broken coil lead to take third.
In the entry level JetPro 400 class, Piopio's Brett Thompson and Megan Brodie also took out their second final in a row in 58.41 seconds, ahead of Taupo's Warren Farr (58.87) and Otorohonga's Patrick Haden (59.35).
Wanganui's Gerry Linklater ended up out of the water during the elimination runs.
The third round is at the Meremere Sprint Bowl on Sunday, February 24.
Points after Round Two
Suzuki Superboat Championship:
1. Peter Caughey (Canterbury) 59; 2. Leighton Minnell (Wanganui) 58; 3. Steve Bron (Feilding) 54.
PSP Group A Championship:
1. Sam Newdick (Hamilton) 60; 2=. Richard Murray (Wanganui), Paul Gaston (Queensland) 57; 4. Bevin Muir (Thames) 52.
JetPro 400s:
1. Brett Thompson (Piopio) 60; 2. Warren Farr (Taupo) 55; 3=. Gerry Linklater (Wanganui), Patrick Haden (Otorohonga) 53.