Maritime New Zealand has a register of ships. It is not available online but may be accessed in a variety of ways. You can contact the register and request verbal information which attracts no fee. If how ever you wish to do any of the following, a fee of $245 (at time of writing) is required:
Inspect the Ship’s Register entry.
Request a Certified Transcript of the Ship’s Entry (includes ownership details and mortgages).
Request a printout of the Ship’s Register entries (includes ownership details and mortgages).
Contact details for the register are available online.
In addition to the current register, you may also perform a search to find if a ship or vessel name is available for registration.