So I asked Customs the question here is the rather vague reply, so another query perhaps more specific will have to be made.
Thank you for your enquiry.
To meet the terms of returning NZ goods and import the boat free of Customs duty and GST, the boat will need to be readily identifiable (i.e. marked or numbered), the exporter and importer must be the same person, the goods must be in substantially the same condition and export entry details must be provided as evidence of the export (to confirm boat was not a GST free sale for export).
From what you have stated, the boat will not qualify for the above and will be subject to Customs charges on importation into New Zealand as per the below.
If the boat was manufactured in New Zealand, it can be imported into New Zealand free of Customs duty. However your shipment will be subject to Goods and Services Tax (15%). The GST is payable on the sum of the cost of the goods plus insurance and freight to get the goods to New Zealand (no freight/insurance charge if vessel sailed under its own power to NZ). Your shipment will also be subject to an Import Entry Transaction fee of $55.71 NZD.
Course is defined as the direction you wish to go and from which the wind is blowing.