But what the talented fly-half had not prepared for was a visit from Superman during the club’s opening pre-season friendly against Leicester.
Hollywood’s latest Man of Steel, Jersey-born superstar Henry Cavill, has since become a season ticket holder and will attend whenever he can.
But, as Penberthy reveals, Superman might not be so keen to challenge the physical prowess of rugby players on his next visit to St Peter.
“It was weird. There was a big crowd at the top of the clubhouse and none of us knew what it was all about” Penberthy told The Rugby Paper.
“It turned out Henry Cavill was up there and I had no idea he was a Jersey boy. It was all good fun and a lot of us had our pictures taken.
“He partied with the Leicester team afterwards and said that if any of their lads could beat him to 50 press-ups, they could use his limousine.
“Tom Croft promptly beat him and got his driver to take him into town. Henry had a good time with us but might not fancy doing that again!”
Aside from meeting Superman, Penberthy has settled well at Jersey since ditching his Cornish comfort zone for a Channel Island challenge.
He has not been alone, with former Pirates colleagues Grant Pointer and Ben Maidment also making a switch Penberthy feels was necessary.
“Last year was a bit hit and miss with injury and I had two groin operations in December that meant I missed three months,” he explained.
“The opportunity came to go to Jersey and I’d been in Cornwall all my life, so I just felt I was in my comfort zone a bit and needed to move.
“Jersey have real ambition over the next couple of years and that’s another reason I came. I want to grow-up a little bit and develop my game.”
Having come through the ranks at Redruth, Penberthy has long been earmarked as a player with the potential to achieve great things.
Much will depend on his progress at Jersey, who have started the season well.
He has people around who can help his progress. Jersey boss Ben Harvey was a playmaker of some repute, while Penberthy is competing for the No.10 shirt with ex-Ulster and Connacht man Niall O’Connor.
“Niall got man-of-the-match against Bedford last week, while I kicked well against Plymouth before that, so it’s a good battle,” Penberthy said.
“I’ve got to push him for a starting place but I haven’t got a bad word to say about Niall because he’s been helping me, which is brilliant.
“I’m only 21 and have got a lot to learn, so to have someone who’s played Heineken Cup rugby with Ulster alongside you can only be of benefit.
“Ben Harvey was a great fly-half in his playing days, too, so you couldn’t have a better pair to mould you and make you a better player.
“We’re always out doing individual skills and Ben is very hands-on. It’s all about improving myself and this is going to be a big season.”
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