Maybe start at Maritime New Zealand's rules page
Where will this boat be operating?

Hi @Lucille N. I might not be entirely correct on this, however my understanding is that as soon a person is being paid while on a motorized vessel it becomes a commercial operation and therefore must have a maritime transport operator certificate (MTOC). This would require the development and implementation of a 'maritime operations safety system' (MOSS) that includes an external auditing regime in order to get an MTOC issued.

The MOSS has to have a section on required qualifications and ongoing training for all crew that is specific to the vessel and the nature of the operation.

Hey Lucille, how have you got on with this? Talking to my son-in-law yesterday, he's project managing a rebuild of wharves at Port Chalmers, his company has done exactly what Matt above has suggested, he was a bit unsure of the qualification their boat master needed but I think they found someone with a Commercial Launch Masters ticket to drive their tender

Hi Steve, The manager for this area decided to not pursue the boat idea due to the safety requirements. That is useful information however. Thanks to you and Matt for the valuable information.