A spate of yacht fires last year prompted the industry to reassess its fire prevention regulations, particularly with regard to the smaller vessels in the fleet. SuperYacht Times takes a look back at these regulations and questions whether lithium-ion batteries are really to blame for the flames?
In a year of dramatic headlines, the word ‘fire’ seemed to crop up a lot in 2022, although the incidents of fire aboard yachts over 24 metres has been fairly constant in recent years. The proliferation of lithium-ion batteries is often blamed, but in many cases the jury is still out. While classification societies handle structure, machinery, electrical and control engineering, regulations covering fire suppression and prevention lie in the hands of Flag States, and therefore are dictated by the various yacht codes. It is here that an interesting fact emerges:
“An initial look at the list of accidents makes it clear that most of the fires last year were on smaller yachts,” says Lorenzo Pollicardo, Technical and Environmental Director at the Superyacht Builders Association (SYBAss). “This means they fall outside compliance with International Maritime Organisation [IMO] requirements in terms of safety, and some of those yachts are built to comply with the Recreational Craft Directive rather than yacht codes.”
“We have drafted the REG Yacht Code as an equivalence to SOLAS, the Load Line Convention and the Maritime Labour Convention, and we have notified IMO accordingly,” says Julian Smith, Principal Surveyor, Global Safety and Compliance at Cayman Island Registry. “So effectively we have used the underlying conventions that are published by the IMO, mindful also of the fact that yachts have their own unique sets of challenges in design and operation that makes them markedly different to merchant shipping.”One of the challenges, Smith points out, is the rate of technological change: “We’ve got a great deal coming through both in terms of electro-mechanical systems on the one hand, and alternative fuels on the other, and then there are electrically driven tenders and toys. And traditionally, maritime regulation hasn’t been known for its agility.”
E-toys and tenders
From Seabobs to electric tenders with power outputs ranging from 1kWh units to 60kWh liquid-cooled battery banks, the proliferation of e-toys and tenders poses a challenge in terms of garage design and fire safety.
“We get a lot of enquiries from crew now about advice for battery toys and about fireproof covers,” says Roxane Ducruet, managing director of Superyacht Tenders & Toys MC. “Our advice is not always to fully charge products on a fast charger, and to consider fireproof battery cases. We work with companies supplying fireproof cases that match the shape of their batteries, and some Flag States are now requesting these. We are also starting to see big superyachts in build that have dedicated battery rooms.”
Another issue is that toys are often designed to be as light as possible, and that may mean critical structure has been removed to keep a battery safe from damage or water ingress. Seabobs have been around for years, and their heavy battery banks are well-proven. “But when you look at foil-boards or anything designed to go above the water, maybe alarm bells should start ringing if they don’t come from a known brand or source,” warns Boyle.
Size matters
For yachts above 500 gross tons there is a significant difference in regulatory requirements compared to those below 500 gross tons. Above 500GT there are A-class boundaries for the tender garage, mandatory requirements for a fixed extinguishing system and a fully addressable fire detection system.
This goes some way to explaining why there is an apparent weighting of fires and smoke-related damage at the smaller end of the fleet (notwithstanding the greater statistical likelihood of fire aboard the much higher number of smaller yachts). The question then becomes, what do shipyards, designers and project managers need to be aware of with regard to new potential regulations, and what else can be done to mitigate risk on smaller yachts? “I think the sub-500GT market is one area we need to look at improving on and we are currently consulting with the industry on how best to do that,” confirms Smith. 
Blame the batteries?
While the cause of many fires last year has not been conclusively established, it seems likely some were started by lithium-ion batteries. Malta’s Marine Safety Investigation Unit’s (MSIU) report into the 2021 fire aboard motor yacht Siempre while it was moored in Olbia, Italy, could not exclude that lithium-ion batteries were either the cause of the fire, or a contributing factor in its intensity and spread. The yacht had numerous battery-powered toys on board and the fire broke out on the open aft deck where the majority of them were stored.
Battery fires are almost impossible to put out. Li-ion battery chemistry means they produce their own flammable off-gases and the fire becomes self-sustaining in a process known as ‘thermal runaway’. At that point gaseous fire agents and water-based suppression systems are simply ineffective. The advice – and current proposed regulation – is to include fire-retardant boxes that can at least contain a fire, plus ventilation systems that extract off-gases from the top and the bottom of a compartment or battery store. There is also a growing number of commercially available detection systems that monitor battery storage compartments for the off-gases or temperature changes that show early signs of cell failure.
Ed Beckett, a naval architect in Burgess’s New Construction team, suggests that as electric tenders grow in popularity the onus is not just on the shipyard, Flag or Class. “It’s important to engage with the tender builder in the design of their battery system and how it will interact with the yacht, not only to ensure it’s safe when out on the water but also equally about how it is stored and charged,” he says. “It is more involved than for a diesel tender, where an owner might just pick the one he wants that fits in the garage space.”
Size comes into play here too. Rory Boyle, naval architect and project manager on the Burgess Technical Services team, says that typically with clients for yachts over 500GT, and for custom projects with custom tenders, it is very easy to have the conversation about safety and suitability. Problems arise at the smaller end of the market where production superyachts are built to tight volumetric tolerances with garages that are designed for specific production tenders, with little room to spare for additional systems or insulation.
“There’s a lot of talk about fire safety, and rightly so, but what we’re trying to ensure is we don’t have the fire in the first place,” says Smith. ”That comes down to battery design and construction, battery storage, charging and battery monitoring. Thermal runaway can be initiated by a number of different failure modes including an internal or external short circuit, excessive storage temperature, or poor battery management practices. It is also interesting to note that we’ve had two cases in the last 18 months of thermal runaway with batteries that were neither on charge nor under load. One was for an e-Foil and the other an e-scooter.”
Even in cases where such toys are stowed in the open, a yacht still presents a combustible environment. Teak decks contain teak oil, fairing compounds are flammable, composite boats burn quickly, while aluminium will melt if not insulated properly and starts to lose its mechanical properties at just 200 degrees Celsius. Investigators into the case of Siempre reported that once the fire had taken hold on the open aft deck “it did not take long for the various flammable fittings, fabrics, wood panels, etc, to contribute to the fire spread through most of the yacht and before the fire could be brought under control.”
It is important also to recognise that not all fires are caused by batteries, and not all battery fires are caused by defective equipment, but the human factor and crew training play a significant role in both. A fire that broke out aboard Kanga when anchored off Croatia in 2018 was caused “in all probability” by the lithium batteries of an electric surfboard. It took less than 25 minutes for the fire to spread from the lower deck to the sun deck, accompanied by explosions. However, crew members were not aware of how dangerous lithium batteries can be, even after some batteries were found to be leaking.
The fire risk associated with Li-ion battery-powered tenders and toys on superyachts has raised awareness of how best to monitor their storage on board. The AX8 Thermal Monitoring Camera from Teledyne FLIR, for example, combines thermal imaging with a camera that can alert the crew to the early warning signs of battery failure. Compact and easy to install with a temperature range of -10 to 150 degrees Celsius and a thermal sensitivity of 100mK, temperature variations of as little as 0.1 degrees Celsius can be flagged up on screen. A change in temperature will sound the alarm long before any smoke appears, which means valuable extra minutes to ensure the safety of those on board and possibly extinguish or at least isolate the problem.
“We know that thermal imaging cannot solve the issue, but it goes a long way to mitigate the risk,” says Hans Groenenboom, Sales Director at FLIR Systems in the Netherlands. “The technology and risks are unlikely to be improved in the very near future, so it’s important for yacht owners to consider as many preventative measures as possible if the opportunity is there.”
Not all yachts are built equal
The fact remains, however, that not all yachts are built to a commercial code particularly if their intended use is purely private. It can be costly and technically onerous to meet all the requirements of code, particularly for elements that are surplus to the intended operational profile. Furthermore, the smaller the yacht, the more difficult it is to include fire systems and fire-damping materials in the structure of the vessel. In this regard, the advice is four-fold.
First, consider building to code equivalence where possible when it comes to fire systems and monitoring, even if the yacht is going to be used privately.
“It is not uncommon for commercial compliance to be on the options list for smaller yachts,” says Beckett. “Much of that compliance relates to safety and security, and when you put it to owners I think a lot of them will say that, actually, they want to protect their asset and their family.”
Second, establish in advance what sorts of tenders and toys the client might want aboard, and to design with those in mind.
“All too often you get to the end of a build and somebody turns up with all sorts of toys that they want to store between the jet skis which are full of petrol,” warns Beckett. “The earlier we have those conversations, the more we can look at dedicated battery charging boxes, or the provision of fire extinguishing equipment.”
“Part of that oversight role is ensuring the boat being built matches the way it is going to be operated,” says Beckett. “There’s nothing worse than designing for storing things in one area, then the owner turning up with a bunch of bikes and things that have to be stored somewhere less suitable.”
And fourth, liaise with the insurance underwriters in order to understand what they require, and what they will or will not cover. This has become more pertinent over recent months as many of the biggest yacht insurers start to rethink their cover of certain types of toys, or at least impose battery handling and storage requirements. Some, especially those insuring vessels over 300GT, insist on vessels being built and maintained to IACS class, pointing out that classification societies are updating their requirements for charging, storage and emergency response regarding potential incidents with Li-ion batteries.
Future regulations
Smith emphasises the importance of taking a measured view of any regulatory changes, which in turn take into account the findings of ongoing investigations into incidents of fire without responding in a knee-jerk fashion.
“There’s a lot to think about when we’re introducing new regulations, and that’s where we are at the moment,” he says. “We are getting a great deal of feedback from the industry and it will be interesting to see the final draft – I am confident it will be measured, technically and commercially feasible, and it will set the appropriate level of additional fire safety measures based on what we understand to be the increased risk.” 
“Once it has been published and people have used that guidance for a while, we will be able to establish whether or not it is wholly or partially suitable, at which point we will be able to finalise the technical content and incorporate it within the REG Yacht Code,” he says.
This article was originally published in Issue 2 of How To Build It, you can download the magazine for free here.