Shipwright

Hi I am trying to find information regarding a William McKenzie(Mackenzie) what we know is that he was a shipwright and emigrated to New Zealand in 1843-44. He married a Mary-Aann Davis in 1844 and the had two sons, William died in 1858.
I have found a William Mackenzie that married a Martha Davis he was 20 in 1841, they married in Poplar in 1838, he isn't in the 1851 Census, his father is listed as John (which would make sense as one of William's son's was a John), he was also a Shipwright, there is also a Matteus Davis listed as Martha's father but I can't find any thing else.
I have tried the usual places here in NZ and they have no record of W McKenzie and M Davis marriage or of his death they have certificates for the son but no information on them.
This is my son's family and even his Dad has no information so any any help would be appreciated.