Stig, cut the stripped part, there's a good chance that it will resprout. That's a way to get a thick hedge with redwoods: plant them in a row, let them grow until 2 to 3 meters, then cut off the trunks. The small stumps will make many sprouts, giving a bunch of fast growing codominant stems. For your, just select the nicest, maybe 2 years after.