When you hear about something crazy happening in the boating world, some accident, tragedy, or close call, what do you do? Do you shake your head and say, “What an idiot, that’ll never happen to me!” Or do you say, “That’s terrible, what steps can I take to make sure that never happens to me?”
Let’s ask the second question, and see if we can find any tips to make us a little tiny bit safer out there. Let’s focus on boat fires: what causes them and how can we make our boat a safer place to be. Chesapeake Bay Magazine recently (Winter 2024) published an article about three fires that occurred within a short time frame around the Bay. The first cold snap of the year always brings a few boat fire-related stories on the news as owner plug in heaters and stress old, weak electrical systems.
But the story is much bigger than the magazine makes it sound. Fire is one of the most dangerous risks boaters face. Understanding the conditions that increase your risk is the first step to mitigating that risk. So, we’d like to expand on the factors discussed and raise awareness about fires on boats.
Fire Prevention and Awareness for Boaters
With a background in professional aviation, part of my training always centered around learning from other’s mistakes. Often, this comes with the solemn task of studying accident reports and seeing what factors contributed to the accident — and, hopefully, getting some insight into how these things could happen to me. From my perspective, this reflection on safety — and a continued desire to do better — is often lacking in the recreational boating community. Not only are accidents shrouded in mystery, but causes are seldom reported and boaters focus on the having fun aspect above all else, including above basic safety.
Here are two of the toughest lessons you have to learn before you can do better:
1. It really could happen to you; you are not necessarily smarter, luckier, or more careful than the last accident victim.
2. Your past history of not screwing up is not enough to ensure that you won’t screw up in the future.
There are a myriad of differences between the cultures of the world of aviation and the world of recreational boating. But I think we can agree that knowing the risks and taking steps to mitigate them are always worthwhile endeavors.
So, back to boat fires. Nothing burns quite as readily — and as toxically — as fiberglass, so fires are a life-or-death matter on boats. A small fire can become a big one in a matter of seconds. And that’s ignoring all the explosive and flammable things we keep stored in our boats: gasoline, diesel, oil, propane, batteries (hydrogen off-gassing), wood, solvents/paints/varnishes, flares, and even waste (methane). To this mix, we run DC and AC wiring, which many times is not installed ‘up to code’ — or, at the least, has become vulnerable and risky due simply to age and use.
Here are a few risk factors that spring to mind; things we’ve personally experienced or seen in our years of boating. This stuff actually does happen pretty regularly, which is a shame since it is often very preventable.
Overloaded Circuits
As a circuit reaches its capacity — which is a factor of the wire size and the components used — things will start to overheat and fail. Ideally, a circuit breaker or fuse somewhere in the system will trip or blow, cutting the circuit and hopefully saving your boat. Unfortunately, circuit breakers and fuses aren’t 100 percent reliable.
I’ve personally experienced a catastrophic failure that should’ve resulted in a tripped breaker but for some reason, it didn’t. They’re simple little items, cheaply made, and — in the cases of a lot of boats — way past any reasonable expectation of their service life. Plus, on old boats you can’t rule out that things might not have been properly installed to begin with.
As a boater, you need to know and constantly think about the capacity of your electrical circuits and ensure that you’re not inadvertently exceeding that capacity. Let’s look at a common example: a single 30-amp shore power circuit.
First off, we might assume that a 30-amp cord attached to a 30-amp circuit should be able to draw 30-amps continuously. But it’s not that simple. This ignores the vessel’s age, the condition of its wiring, the marina power pedestal’s reliability, and the connections’ security.
Some safety factor needs to be taken into account. When plugged into a 30-amp plug, I don’t like to exceed more than 20-22 amps total, say 70 percent of the maximum. And I’d be pretty nervous about pulling this load for more than a few minutes — better to keep it under 50 percent, in my mind.
So, how do I know what I can use? It’s important to have a rough understanding of some basics of electricity. Wattage is a better power consumption measurement than amps are, since the measurement works regardless of voltage.
volts x amps = watts
110v x 30a = 3,300 watts total load
70% of 3,300w = 2,310 watts max useable load
How much can you run on 2,300 watts? Here are some common appliances that we use on our boat, as examples.
| Electrical consumer | Average watts drawn |
|---|---|
| Marine air conditioner/heat pump | 1000w |
| 80a battery charger (bulk mode) | 1152w |
| Water heater | 700w |
| Portable electric heater | 750 – 1400w |
| Induction stove, single burner | 1300w |
| Electric kettle | 1200w |
| Instant Pot pressure cooker (Mini 3qt) | 650w |
| Electric toaster | 900w |
It’s a bit of an oversimplification, but you can see from this list that nearly all appliances we use on the boat are somewhere around 1,000 watts.
So, with 2,300 watts available from our 30-amp circuit, we don’t use more than two major appliances at a time. We’ve built in enough fudge factor that we don’t feel worried about the little items we have plugged in, such as computer monitors, laptop chargers, and Starlink. These items only total up to be about 120 watts.
By following this rule, we a constantly cycling things on and off to suit our needs. At a dock, we usually leave our AC/heat on all the time. That leaves space for one other big consumer. We alternate the portable heater, the induction hot plate, and the water heater as needed. And that’s important: We never leave our water heater on all the time. We only switch it on for an hour or two when we know we’ll want hot water, such as when doing dishes or taking showers.
A better solution would be to have more capacity built into the system: A 50-amp plug, cord, and breaker panel would allow you to total 3,850 watts (using the 70% rule) of useable load. Alternatively, many boats install a second 30-amp panel with a second cord. But many older boats aren’t set up this way, simply because it’s cost-restrictive to revamp the entire electrical system. If someone is spending $5,000 or more to add a marine air conditioner, it’s a hard sell to get them to double that cost by installing a whole new electrical system, too.
But no matter how many amps your system is designed for, all boat owners need to be aware of the load on their system and keep it to a minimum. Just because your system has twice the capacity doesn’t mean it’s harder to overload. With more capacity comes more excuses to use it, more appliances and toys. In other words, the same problems that you’d have with a smaller system.
Shore Power Cord Connections
The math and notes above assume a properly functioning, properly installed system. In every marine electrical system, there is one huge weak leak: the shore power cord plugs. Marine How To has a great article about why these plugs are the absolute worst: a poor design from 1938 (!!) that was never intended for marine use. In the article, a plug is broken apart and tested, revealing that the electrical contacts inside are TINY.
Shore power connections with standard connectors are a common contributing factor to boat fires. When the connectors in the plug don’t make contact, electricity arcs between them, heating up, melting the case, and eventually setting fire to the boat. The shocking thing (pun?) is that it doesn’t require much power use to start the process. If the plug fails, just running one little appliance will do the trick, and no breakers will pop!
We’ve unfortunately seen this ourselves. Once, we were plugged into 15-amp service and only drawing 5-8 amps total. Unfortunately, the old, standard connector was not plugged in perfectly straight. It was at a slight angle, and the collar was cross-threaded slightly. It was only obvious after close inspection after the problem occurred — when it was too late. Thankfully, we were onboard at the time and smelled the tell-tale burning of electrical insulation and plastic. We immediately began searching for the source and found the charred connector.
One solution (as suggested by Marine How To and adopted by our crew after the incident) is to install a SmartPlug. These are a new design plug for the boat-side of your shore power cord. You can retrofit them to your old cord or buy an entirely new cord set. Unfortunately, there’s nothing you can do to change the shore-side connector at a marina, but you could install a SmartPlug on your home dock.
The SmartPlug’s design is better for two reasons. On one hand, it has big prongs that make excellent electrical contact and resist shorts. On the other, the plug installs squarely into the receptacle on your boat. If it’s not all the way in, the locking arms are popped out in a very obvious way that catches your attention.
The story’s moral is bigger than just, “Buy and use a SmartPlug” (although I think everyone should). Instead, the moral is more about intimately getting to know your shore power cord. Inspect both ends and watch for tell-tale signs of arcing, like black marks on the plastic. Inspect the prongs for corrosion, which could build up resistance and cause heat. When plugged in at the dock, occasionally check that the connector is properly plugged in. Put your hand on the connector when you walk by to check for heat (although this isn’t a guaranteed tell). And, while you’re at it, keep an eye on your neighbor’s shore power plugs, too. Tell the owners or the dockmaster about any little problems before they become big problems.
Finally, make sure your shore power cords are long enough. The plug isn’t adequate enough to guarantee safety when there is slack in the cord. When the cord is pulled tight due to the boat’s motion or just being stretched to its max, there’s no way the plug will do its job.
Improperly Installed Wiring and Equipment
Boat owners sometimes take on projects on their boats without being familiar with the best practices of marine wiring. Those best practices are published but not by the government; they are not free, and they are not available for everyone to look up online. Instead, best practices are hidden behind professional membership dues and training. If you pay your dues, you can learn what the rules are.
That allows a ‘professional’ to advertise that they’ve paid their dues and are certified, but it means that Joe down in Slip F-18 with the 40-year-old cruiser doesn’t have a clue what he’s doing, and all the Googling in the world isn’t going to help him. The chances he’s paying the dues and going to school? Zero. The chances he’s hiring a guy who went to school to learn this stuff? Very close to zero. Joe does all the wiring in his house, after all.
That’s all fine and good, but one day Joe will sell that boat to somebody else. The new person now gets to deal with whatever Joe did. What Joe did probably worked fine for him, and it might keep on working fine. Or it might fail suddenly. Maybe Joe never left the dock, and the new owner wants to travel.
Buying any used boat means dealing with what the previous owner did, and sometimes, what they did may make the vessel unsafe. A pre-purchase survey helps, but it’s vital to analyze the quality of the work you can see and figure out what it might mean for the quality of the work you can’t see. Surveys are not always as thorough as they ought to be.
Here’s a fun example, again from personal experience. We once started smelling smoke and had to trace an electrical short. We discovered that the AC wires to our inverter/charger were cut too short. They were stretched to their limit and finally failed one day, pulling loose from the inverter’s connectors and shorting. Thankfully, we caught it before any major problems. We shut the system down, reran the wires, and sent the inverter off to be inspected and refurbished. No big deal, but it could’ve been much worse.
Lithium Batteries (The Ones You’re Not Worried Enough About)
Lithium batteries are a hot topic in boating right now. Many people are installing them as their house batteries, and many people are very concerned about their safety. But those aren’t the batteries I’m worried about, and here’s why.
The batteries being installed as house banks are Lithium Iron Phosphate batteries, aka LFP or LiFePO4. This isn’t the same type of lithium battery you find in other places like your laptop or cellphone. LiFePO4 batteries are dramatically safer and less prone to problems. Plus, if they’re installed correctly, I don’t believe they’re any more dangerous than the regular lead-acid batteries they replace. In fact, I’d venture a guess that a properly installed, new system is safer with LiFePO4 batteries than an old, worn system running lead-acids, but that’s a debate for another time.
The batteries that worry me are all the others we all have with us. High-end electronics, like your laptop and cell phone, are probably okay. But on the other end of the spectrum are the ones that come in goodies you might not worry enough about. Two examples that come to mind — and that I can directly link to boat fires, as reported in the media — are electric scooters/e-bikes and rechargeable drill batteries. Not only do the batteries themselves concern me, but the cheap chargers and poor build quality of the protection circuits are doubly concerning.
Here are three news stories worth thinking about.
Via Keys News: In July 2023, a 70-foot Viking yacht caught fire during the night in a Key West-area marina. Two men were treated for burns, but a woman died onboard. After the accident, investigators suggested (an eye witnesses corroborated) that the cause may have been an e-bike that was left charging on the back deck of the yacht.
Via ACR Survivor Stories: The 37-foot sailing vessel caught fire in the Gulf of Mexico while enroute from Texas to Mexico. The crew reported that the fire started when the battery of a rechargeable drill stored in a locker exploded four times at 2:00 am. All the bad stuff happens at 2:00 am. The crew could not extinguish the Li-ion battery fire and exhausted their two fire extinguishers. They were rescued by a USCG chopper.
Via Boating Magazine: Finally, one other cautionary tale worth studying. A major news story at the time, the 75-foot expedition dive boat Conception caught fire in the night while at anchor off of California. 34 people died in the fire. It’s been widely speculated and reported that the cause of the fire was a consumer electronic device with a Li-ion battery (i.e., a camera or cell phone) left plugged in to charge. Boating Magazine has a synopsis of the case and lessons as they may apply to recreational boaters.
I bet that, given a minute or two to think about it, every boater could list 10 to 20 lithium-ion batteries on their boat. Given the slamming that boats take and given the fact that many of these devices were never intended for the marine environment, there’s a considerable chance that these batteries will eventually fail. Usually, it’s noticeable when things are plugged in — and that’s when I’m extra cautious with them. But the story of the drill battery above reminds us that just the motion of being in a boat could cause a catastrophic failure of these batteries AT ANY TIME.
For argument’s sake, here are the Li-ion batteries on my boat that I can list off the top of my head. How many can you list on your boat, and are they stored in a way that protects them from vibrations? Do you unplug their chargers when you leave the boat or go to sleep for the night?
4 laptop computers, 2 cell phones, 1 tablet, 1 portable power pack, 2 Kindle e-readers, 1 action camera, 2 handheld VHFs, 3 flashlights, 3 high-capacity Ryobi drill/tool batteries, 2 SLR camera batteries, 1 drone, 3 razors/clippers, 1 toothbrush.
Tips for Fire Safety on Boats
I cannot pretend to be an expert in this area, but I’ve given a lot of thought to fire risk and what to do on our little sailboat. Here are some thoughts to help guide you as you think about how they might apply to your boat and your boating lifestyle.
Know and Plan Evacuations
- Most small boats have very few ways out. If you imagine a fire breaking out right at the companionway, how do you escape?
- Can you quickly (i.e., immediately) launch your life raft (or at least your dinghy) in case of fire? Is it worth considering leaving the dinghy in the water so it’s ready to go when anchored for the night?
- I often hear boaters (particularly owners of “unsinkable” catamarans) foregoing life rafts. This argument seems to completely ignore the risk of a fire onboard.
- If you sleep in the v-berth, can you evacuate out the overhead hatch? Make sure it isn’t blocked by dinghy, sails, or security measures!
- Have your ditch bag ready to go at all times.
- Make sure your whole crew knows the plan, the dangers, and what do to in case of a fire on board.
- You’ll probably smell an electrical short before you ever spot it. Always investigate anything until you find the cause. If you suspect an electrical short, cut all breakers and power to the system ASAP.
Fire Detection
Early detection is the key to saving lives. Invest in good fire detectors and keep the batteries fresh. I like to test mine regularly by making toast.
Fire Extinguishers
Invest in the best fire extinguishers you can: “ABC” (tri-class) extinguishers are rated for the most types of fires. Having anything less (i.e., the cheap ones, only “BC”) is just silly. Even an ABC extinguisher cannot put out a lithium battery fire, however. The ABC refers to what the extinguisher can put out: A=combustable solids (wood, fiberglass), B=combustable liquids (grease, gas, diesel), and C=electrical fires.
There are CG minimums depending on the size boat. In my book, you can’t have too many. We have four on our 38-footer. Overkill? Maybe, but what’s the harm of having it on hand?
Have your extinguishers mounted, visible, and at-hand. They’re no good buried in a locker or cabinet.
West Marine has a good guide to understanding fire extinguishers and their ratings.
On commercial vessels, fire extinguishers need to be inspected and signed off every year. The rule doesn’t apply to recreational boats, but I once had an insurance survey that made me do it anyway. It’s not a bad idea to do your own inspection: shake the canister to make sure nothing is clumped or settled, inspect the nozzle and head for corrosion or blockages, check the gauge is in the green, and that the locking pin is securely attached. Put a sticker with the date inspected on the extinguisher so you know when it’s time to do it again.
I also keep a fire blanket in the galley where I can grab it in case of grease or cooking fires.
There are companies now making fire extinguishers specifically designed for Li-ion battery fires. If you have some of these on your boat, it might be worth the cost of carrying one of these around (although, to my knowledge, these do not meet USCG requirements, so it would need to be kept in addition to the regular CG-approved extinguishers).
Propane Safety
I use a propane cooker daily, and I’m very happy with it. It’s hard to justify converting it to electricity on a small boat with no generator. And, would having an appliance that draws so many watts and puts such a load on the system really be any safer? In the end, it all comes down to having a properly installed and safe system, no matter what type of fuel you use.
In the US, boats with propane systems are required to have cut-off solenoid valves. These shut off the fuel supply at the tank to ensure that fuel can’t flow in the system when you aren’t cooking. Never rely solely on the appliance as the cut-off since it’s used heavily and not entirely foolproof. Use the solenoid valve or close the valve on the bottle after every use.
Storage of propane is another issue. Propane is a special kind of dangerous because it’s heavier than air. In a boat, it will settle to the bilge and build up until some spark ignites it. Another heavier-than-air substance to consider is acetone.
These substances need special storage facilities on the boat. A proper propane locker vents from the bottom and overboard, completely sealed from the rest of the boat.
If you use the small 1-pound propane bottles for heaters or grills, consider why they should be stored, as well. They rust easily and can fail.
As a final risk mitigation measurement with propane, consider installing a gas sniffer and detection system. These will alert you if gas starts to build up in the bilge.
Additional Resources and Links for Fire Safety
Boating Magazine: California Dive Boat Fire, What Lessons Can We Learn?
FEMA Boats and Marinas Fire Prevention
BoatUS Fire Equipment Study Guide
BoatUS: Your boat’s on fire, now what?
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