Keep the Flames at Bay: Top Strategies for Fire Safety and Storage of Li-on-Powered Craft on Yachts

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When it comes to fire safety and storage of small Li-on-powered craft on yachts, precautions are paramount. How can crew and yacht owners ensure the utmost safety and protection for their valuable vessel? Here are key practices and measures outlined by the Maritime and Coastguard agency in their MGN 681 (M) guidance. Bellow is an summary from the guidance, we included a link to the full guidance at the end of this post.

Why do we need guidelines?

Industry groups estimate 16 total losses due to fire on yachts between August 2021 and August 2022; while some of these fires’ causes are known and unrelated to the recommendations in this guidance (such as arson, collateral damage from another fire, etc.), about half of them have not yet had their causes determined. Out of many possible explanations, one potential explanation for the unexplained fires is that they were caused by lightning. Small electrically driven craft and other vehicles, like electric tenders, electric jet skis, electric foils (e-foils), and other personal watercraft powered by Li-ion batteries, are becoming more and more popular.

San Lorenzo Yacht Fire in 2021

Although this advice is intended for yachts that adhere to Part A of the REG Yacht Code, any Yacht that carries craft with Li-ion batteries can apply the concepts and guidelines presented.

Storage and charging

Electric-powered personal watercraft and small craft should be stored in spaces that meet the minimum requirements of Part A of the REG Yacht Code.

Spare or removed batteries with a rating above 100 Wh should be stored in dedicated cabinets or lockers constructed according to recognized international standards.

Damaged electric craft and batteries should be stored with extreme caution and unloaded as soon as possible for disposal or repair by a qualified service provider. Charging of damaged batteries should be avoided, and if damage occurs during charging, charging should be stopped immediately.

Minimize the variety of battery types and charging systems on board to avoid hazards resulting from incompatible equipment or incorrect handling and charging procedures

Monitoring systems should be integrated into the ship’s alarms and control system where practical, such as Battery Management Systems.

Battery Management Systems

The BMS is responsible for monitoring various parameters of the battery system, such as total battery current, total battery voltage, individual cell voltage, battery current, and temperature.

It regularly checks the battery’s health and can regulate the temperature through thermal management systems to maintain optimal performance, even in ambient temperatures outside the ideal charging range of 15°C to 35°C.

Battery Management System diagram

When the BMS detects a problem, it takes appropriate countermeasures based on the severity of the fault, ranging from deactivating faulty cells or modules to disconnecting the entire battery from the electrical system to prevent overcharging and thermal runaway.

Failure of the BMS can lead to battery failure and the risk of a battery fire.

Li-ion Batteries Fire Risk Overview

Li-ion battery fires can continue burning without additional oxygen and may generate high amounts of heat even after fire extinction, making them susceptible to re-ignition.

  • Typical battery sizes for various electric-powered personal watercraft are provided, ranging from 1 kWh to 100 kWh.
  • Li-ion battery cells are considered dry cells, and damage to the battery may result in leakage of clear fluid or blue coolant, indicating battery damage.
  • Thermal runaway is the event most associated with catastrophic Li-ion battery fires, caused by the heat generated within the battery exceeding the heat dissipated. This can lead to fire spread or explosion if not controlled.
  • Off-gassing occurs during thermal runaway, releasing flammable and hazardous gases such as carbon dioxide, carbon monoxide, hydrogen, and volatile organic compounds.
  • Rapid heating of battery cells in a damaged Li-ion battery can be indicated by hissing, whistling, popping sounds, a sweet chemical smell, black “smoke” (nanoparticles of heavy metals), or white vapor. Appropriate firefighting measures should be taken in such cases.

The risk of fire is significantly increased when a Li-ion battery is damaged, particularly in situations where saline penetration is likely, such as with personal watercraft.

Fire Detection and Alarm

Battery compartments should be equipped with a monitoring system that includes fixed smoke, heat, and gas detectors according to the manufacturer’s recommendations.

Closed-circuit television (CCTV) cameras should provide surveillance over battery storage and charging areas, and an infrared (IR) camera or thermal imaging system is recommended.

Fire detection cameras from SIRM UK

An audible and visual alarm should activate locally and at a control position in case of detecting abnormalities such as temperature increase or smoke.

The use of thermal imaging cameras, while not required, is a potentially useful tool for early-stage fire risk detection. Handheld or fixed thermal cameras can effectively identify battery fire risks and overheat in personal watercraft.

Manufacturers suggest that the minimum temperature for potential thermal runaway in batteries ranges from 60 °C to 70 °C.

A fixed fire detection and alarm system should comply with the requirements of SOLAS II-2/Part A/Fire Safety Systems Code Chapter IX.

Off-gas detectors, although not required, are a developing technology that may aid in early-stage Li-ion fire detection. However, false alarms may occur due to the presence of exhaust gases from conventionally fueled vehicles.

Fire Suppression

Battery compartments should be protected by an automatic water-based fixed fire-fighting system that can be manually or automatically activated from outside the space.

Water-mist systems being the most effective solution for battery-fire suppression.

HI-FOG system

A minimum of two portable fire extinguishers suitable for battery fires should be located outside the battery space or near the entrance(s), and battery-driven tenders or large vehicles should have an additional portable extinguisher on board.

Battery fire suppression blankets and/or containment bags appropriate to the battery inventory should be carried, taking precautions for heat exposure and potentially explosive and toxic gas buildup.

Trained crew members should monitor batteries or vehicles/craft containing batteries and be ready to undertake additional fire-suppression measures until the vehicle is removed from the vessel.

Personnel responding to Li-ion battery fires should be aware of the risks posed by electric equipment and ensure that the ship’s electrical supply to the battery being charged is cut/isolated before firefighting.

Crew Training

Crew members should receive training in the safe operation, storage, and charging of electric watercraft and other vehicles carried onboard, including identification of potential damage and proper procedures for disposal or quarantining of damaged equipment or batteries.

Safe Operating Procedures should be included in the vessel’s Safety Management System
Fire and Safety plan

The vessel’s safety management systems should include a response plan for dealing with battery fires, and drills for handling such fires should be conducted at agreed intervals with the administration.

Crew members should be fully trained and competent in the use of specialist equipment such as Li-ion specific fire extinguishers, fire blankets, IR cameras, etc., used for fire detection or firefighting of Li-ion batteries.

Crew members should be trained to identify early signs of battery problems, including the potential for sudden thermal runaway, the difficulty in extinguishing Li-ion battery fires, the hazardous gases produced during battery fires, and the risk of re-ignition even after fire suppression.

  • A post-incident action plan for the quarantine or disposal of batteries following battery fires, along with a clean-up plan that complies with local regulations for runoff, should be developed and included in staff training as part of the vessel’s safety management system.
  • It is recommended to appoint a named person onboard, such as the Safety Officer, Master, or Chief Engineer, as responsible for the safe operation, maintenance, and response to emergencies involving Li-ion batteries, considering their unique challenges.

Given the rise of the use of Li-on-powered craft/devices onboard is not an easy task to keep track of, but the crew must be aware of the new possible dangers of such equipment and how to handle them.


Small electrically driven craft and other vehicles, like electric tenders, electric jet skis, electric foils (e-foils), and other personal watercraft powered by Li-ion batteries, are becoming more and more popular. The question of whether the fire prevention, detection, and suppression systems that were previously installed on large yachts for earlier generations of petrol-powered craft are suitable for the newer battery-powered ship has not been thoroughly examined, and as such new practices need to be discussed, tested and implemented as soon as possible.

Stay safe!

Here is a link to the full MGN 681 (M) Guidance

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