A new report from the Lloyd's Register Maritime Decarbonisation Hub calls for the shipping industry to adopt a unified approach to designing and assessing emergency safe havens on ammonia-fuelled ships.

The report, titled Safe Havens for ammonia-fuelled ships, addresses a critical safety challenge as the maritime sector explores ammonia as a zero-carbon alternative fuel. Ammonia is highly toxic to humans, and even small leaks can pose life-threatening risks to crew members if inhaled. Yet the fuel is attracting growing interest because it contains no carbon, meaning its combustion does not produce CO2 — a key attribute as shipping works toward the IMO's revised strategy to reach net-zero greenhouse gas emissions from international shipping by or around 2050.

A safe haven is defined in the report as a sealed refuge where crew members can shelter from toxic ammonia gas during a leak. Inside this refuge, crew can maintain control of the vessel or, if necessary, prepare to abandon ship.

The International Maritime Organization (IMO) has published interim guidelines for the safety of ships using ammonia as fuel, which require ammonia-fuelled vessels to be fitted with safe havens. However, the report argues that these guidelines provide only high-level requirements, leaving significant room for different interpretations by shipbuilders, classification societies, and flag administrations.

This ambiguity, the report warns, could result in inconsistent and varying levels of safety across the future ammonia-powered fleet. With several major engine manufacturers and shipyards already developing ammonia dual-fuel engines and ordering ammonia-ready vessels, the report's findings come at a pivotal stage — before the first generation of commercial ammonia-fuelled ships enters widespread service. To address this, the report proposes a common assessment framework to ensure a more consistent and rigorous approach to safe haven design and evaluation.

The recommendations in the report draw on established practices from the offshore oil and gas and chemical industries, where toxic gas hazards have long been managed through engineered shelter-in-place systems.

According to the report, safe havens should be treated as an integral part of a vessel's wider emergency response system rather than as standalone features. They should be designed around three core functions: protection, command and control, and accessibility.

The report also recommends that safe havens be tested against standardized worst-case ammonia release scenarios, including major bunkering incidents, to ensure they perform adequately under extreme conditions. Additionally, safe havens should be maintained throughout a vessel's entire service life to ensure continued effectiveness.

The full report is available from the Lloyd's Register Maritime Decarbonisation Hub.