Marine Biosecurity - Vessel Cleaning

Clean Boats - Living Seas, A boatie's guide to marine biosecurity
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Boat Cleaning Video
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Why clean your hull?

Maintaining a good cleaning and antifouling routine for your vessel is key to being a good biosecurity citizen.

Marine pests love a dirty boat bottom – they can take hold in the fouling fuzz and hitch hike to new locations.

Before you know it, they can quickly establish themselves, potentially seriously affecting marine habitats, food chains, fish stocks, recreational activities and aquaculture.

When should I clean it?

We highly recommend slipping your vessel for a good clean and the reapplication of a liberal coating of antifouling paint before you sail from your home region to another region of New Zealand.

A good general rule is an annual clean and reapplication of antifouling, but many boaties find a good thorough coat of paint lasts longer than this, with their more frequent maintenance being a waterblast. The aim is to have your vessel carrying no more than a light slime layer at any time.

If you use antifouling paint on your hull, it should ideally be replaced at the interval recommended by the paint manufacturer, or if the paint has been scraped or damaged. The usual period for reapplication for moored pleasure craft is one year.

At the very least you should check that your boat is free of bio-fouling growth such as seaweeds, barnacles, mussels and oysters before leaving your home region.

How do I clean it?

Once your vessel is on a hardstand or haulout, dislodge all plants and animals and dispose of them in a bin that will go to a land-based rubbish dump.

Thoroughly waterblast or hose and brush down the areas of the vessel that are normally under the waterline. Pay particular attention to the following areas:

Diagram of areas on your boat to target

  • the hull, keels and stabilisers
  • intakes and outlets
  • propellers and shafts
  • rudders, rudder shafts and casings, rudder recesses
  • anchors, anchor chains and anchor wells.

If your cleaning is not being carried out in a boat maintenance facility that has treatment and containment systems, try to ensure there is no run-off directly back into the sea or waterways. At a minimum make sure all solid material is collected and disposed of in a land-based tip (as above).

What about antifouling preparations?

Using an antifouling paint correctly will stop fouling building up on your vessel's hull.

Use a paint that's suitable for the type of vessel and its use. Factors to be considered are the usual speed of travel, the amount of time your boat is kept at mooring or berth and the material composition of your hull. Antifouling works best with two (or more) liberal coats applied to a clean, sanded and primed hull. Let the antifouling dry completely between coats and ideally leave your vessel out of the water for 24 hours after the application of the final coat.

Where can I clean it?

There are haulout facilities and hardstands at most of New Zealand’s marinas. Marina operators will be able to advise you of local cleaning facilities.

For a full list of marinas, their facilities and contact details, visit: (offsite link to or check the local Yellow Pages phone directory under Boat-Ship Maintenance or Ship Chandlers.

What's in it for me?

  • Extend the life of your boat and gear
  • Reduce vessel running costs (lower fuel consumption)
  • Reduce maintenance costs
  • Protect our coastal waters for future generations
  • Maintain our enjoyment of the marine environment for activities such as fishing, swimming, sailing and diving

Page last updated: 18 August 2016