Two late tries from Rob Stapley triggered a Rams comeback to clinch maximum points for the fourth successive National 3 South West game.
Rams, up at the break, suddenly found themselves 23-17 down midway through the second half.
Head coach Mike Tewkesbury found it hard to explain the third quarter collapse.
He said: “It was odd. After half-time we lost concentration and made the sort of mistakes I haven’t seen before nor want to see again.”
“Exmouth have some very useful backs but when we switched to a forward orientated game we took control again.”
“It was a decision managed by the players themselves. I felt they showed a great attitude, the front row doing particularly well.”
Two Jevon Marsh tries - taking his seasonal tally to nine - plus a Shaun Brown conversion gave Rams a flying start and it looked likely to be a cakewalk
But for the rest of the half the Sonning men saw very little of the ball despite winger Joao Costa speeding away on the blindside just before the break to make it 17-6.
Then Gensians conceded a couple of tries in the first four minutes of the second half to Ross Morshead and Tom Kill and Andy Powell added a conversion to his two earlier penalties.
Rams looked in disarray when Ben King crossed for a third touchdown. However they finally got their act together and the pack started to hammer the Exmouth line.
After 68 minutes they were rewarded with a Stapley pushover try before he finished off more superb driving play by the pack - Brown adding the extras twice.
In the closing minutes Rams kept up the pressure to run down the clock and finish well in charge.

Marsh; Costa, Reynolds, Aaron Hopkins, Gosling (Flynn 58); Brown, Raitt; Baker, M Clarke (Fisher 75), Rumble, Root, Turner, Amor (Davies 43), Azza Hopkins, R Stapley.