We're running a nation-wide inspection campaign focusing on hazardous gases on domestic commercial vessels from 2 February - 30 April 2026. Find out what to expect and how to prepare.
Focused inspection campaign summary
Purpose: To ensure that vessel owners, operators and crew understand the risks associated with hazardous gases and are complying with the requirements of Marine Order 504.
Location: Nation-wide
Timeframe: 2 February until 30 April 2026
Target: Domestic commercial vessels with:
- sewage and organic waste systems
- engines, generators, fuel-burning appliances
- stored high-pressure gases.
Focus areas
If we inspect your vessel, we will look for:
- documented risk assessment and procedures for hazardous gases
- crew training on hazardous gas identification and response
- Information signage provided to class 4 hirers regarding hazardous gases
- sufficient ventilation in sanitary facilities.
What to expect
Inspectors will make focused inspections in conjunction with regular domestic commercial vessel inspections using a checklist. Where a deficiency is found against the checklist, the inspector will discuss it with the person in charge of the vessel with a view to ensuring the vessel is brought into compliance.
Inspection checklist
- Does the vessel risk assessment identify and control the risk of hazardous gases?
- Does the SMS identify regular programmed inspections and maintenance of sullage tanks and plumbing?
- Have crew undertaken any induction, on-board familiarisation or training for identifying and responding to hazardous gases?
- Does the SMS include clear and relevant procedures for the pumping out of blackwater, greywater, or bilgewater tanks?
- Do the toilet areas have sufficient mechanical or natural ventilation to open air?
- Is the vessel fitted with, or do crew have access to hazardous gas monitoring devices? (not mandated by the NCSV or USL code but may be a risk control to be implemented under the vessel's SMS, particularly for enclosed spaces)
- Class 4 only: Is information provided to hirers about the risks of hazardous gases such as carbon monoxide, hydrogen sulphide and carbon dioxide?
- Class 4 only: Is signage or labelling in place warning of the dangers of carbon monoxide or hydrogen sulphide in confined areas?
Download a printable version of the checklist PDF153.42 KB.
How to prepare
- Read guidance about how to reduce the risks of hazardous gases.
- Do a risk assessment and include controls for hazardous gases in your vessel's SMS.
Last updated: 24 November 2025