Commercial vessels

If you're bringing a commercial vessel into New Zealand, you need to meet certain rules around biofouling. Find out the requirements and how to meet them.


What are commercial vessels?

Commercial vessels generally move at medium to high speeds and aren't likely to be stationary for long periods of time (aren't long-stay vessels).
They include:

  • commercial cargo vessels
  • trading ships
  • container ships
  • bulkers
  • cruise vessels.

What you must do

If you're the operator of a commercial vessel coming to New Zealand, to meet our biofouling rules you need to:

To demonstrate best practice, we recommend you create and follow a biofouling management plan and record your maintenance activities in a log book.

If your vessel requires cleaning before arrival in New Zealand, you'll need to keep documented evidence of cleaning and a quarantine inspector may ask you for it.

Requirements depend on length of stay in NZ

Many commercial vessels fall under MPI's 'short-stay category' (planning to be in New Zealand for 20 days or less and only visiting designated ports) when arriving in New Zealand. Vessels coming in as 'long-stay vessels' (planning to be in New Zealand for 21 days or more or visiting places that aren't places of first arrival) are only allowed a slime layer and goose barnacles. Short-stay vessels are allowed slightly more biofouling. Allowable amounts of biofouling are set out in the biofouling craft risk management standard.

Download the craft risk management standard for biofouling [PDF, 241 KB]

Photos to help you assess biofouling

Continual maintenance of commercial vessels

Continual maintenance involves ongoing management of biofouling, including:

  • having a biofouling management plan specific to the vessel
  • coating the hull and niche areas with antifouling paint appropriate to the operating profile of the vessel
  • regularly inspecting and cleaning the hull and niche areas
  • keeping records to show how biofouling is managed
  • having contingency plans in place to minimise fouling if the vessel falls out of its operational  profile.

Use suitable hull antifouling systems

The vessel hull should be painted with antifouling that can prevent biofouling between dry dockings.  The antifouling applied should take into account:

  • the planned time between dry dockings
  • the ship's speed and activity
  • any periods that the vessel will be stationary.

Where antifouling paint is damaged, consider in-water repair of the paint in the area, even if minor. 

Maintain, inspect and clean niche areas

Vessel with close ups of niche areas: rudder hinge, propeller, sea chest, bilge keel and bow thruster


Sea chests

  • Paint internal surfaces with antifouling paints suitable for the flow of seawater.
  • Use marine growth prevention systems (MGPs), such as chemical dosing systems, where possible.
  • Regularly use steam blow-out pipes if fitted in sea chests to reduce biofouling growth.

Sea inlet pipes and outlets

Apply antifouling paint inside pipe openings and pipework. Antifouling paint adheres and lasts longer if:

  • all sea inlet pipes and outlets have rounded surfaces, avoid corners where possible
  • grates on seawater intakes are made with round bars.

Hull appendages as niches

Any hull appendages can be niche areas, even when painted with effective antifouling. You may need to include them in a maintenance and cleaning programme.  Hull appendages include:

  • dry docking support strips
  • bow and stern thrusters
  • bilge keels, cooling scoops and propulsion scoops
  • rudder hinges and stabiliser fin apertures.

Hull appendages that can't be painted with antifouling paint – because it affects their operation – may need additional maintenance and cleaning. These include:

  • anodes
  • velocity probes
  • echo sounders.

Internal seawater systems

Effective marine growth protection systems (MGPS) (such as chemical dosing systems) can be fitted to internal seawater systems prone to biofouling. Use these systems regularly and monitor them to make sure they're working well. If MGPS haven't been fitted or haven't prevented biofouling, treat internal systems before arriving in New Zealand.

Find out more

Who to contact

If you have questions about biofouling requirements for commercial vessels, email standards@mpi.govt.nz 

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