Pritchard, 30, quickly grabbed his cellphone and started recording.
"One literally came up under the boat and then decided to give us a little nudge. Gave us a push,'' he laughed.
"It was bloody crazy seeing that - it was cool.''
The orca hit the vessel with so much force that Pritchard fell back. Seconds after he got back up, another orca hit the boat again.
On the video footage later shared with friends online, Pritchard gives a commentary of the events unfolding in front of him.
"Check out these fellas come for a look! (sic). Wooh! There's a whole pod of them.''
The camera suddenly jerks, as Pritchard falls, and he says: "Wow! He [expletive] hit the boat!''
Another mate can be heard in the background, roaring with laughter.
Pritchard said he and his mates had enjoyed their trip and they came away with snapper, kīngi and hāpuka to show for it.
But the orca encounter was the catch of the day.
"That's the first time I've had an encounter like that, definitely. I've seen them before, but nothing like that.
"It was incredible.''