It seems like the plot of a science fiction movie: the sun starts ejecting massive bubbles of superheated plasma that ingnite tremendous geomagnetic storms on Earth, strong enough to short out every electrical system on the surface AND in orbit. The planet is effectively knocked back to the 18th century when gas-lamps and horse-and-buggies were all we had to get around and light our way.
In May 2024, such a storm did occur (though, of course, not to the extent I just described). It was strong enough, however, to generate stunning aurora borealis (a.k.a. the northern lights) that could be seen as far south as Mexico. It was also strong enough to throw off GPS-guided tractors, causing huge headaches for farmers at the time. The May 2024 storm was even given a rating of 5 (Extreme) on NOAA’s 1-to-5 scale for Geomagnetic Storms.
While this may seem insignificant to some, we often forget as sailors how reliant we have become on our GPS-enriched systems and other electrical equipment. So when we are a week in on a 20-day ocean crossing and a G5 storm hits, knocking out our navigation and communication equipment… do we know what to do? And, how likely is this to happen?
Let me put you at ease right away. Science says this is a “not very often” event – not often, but not negligible either.
Smaller geomagnetic disturbances happen relatively frequently. They may produce minor GPS errors or dropouts, or interference.
Larger storms like the “Carrington Event” (1859) are rare. It was the largest recorded geomag storm in history; telegraphs worldwide electrified their operators, caught paper on fire, and kept functioning even with their batteries disconnected. If an event of that magnitude hit today, you can just image the kinds of chaos that would create with the number of electrical systems in use.
The May 2024 storm was one of the strongest in recent years. It showed that powerful storms are possible with potentially serious effects.
So as a cruiser, you won’t see catastrophic solar storms often, but you will see mild to moderate ones, and it’s not a bad idea to be ready for the rare big one.
Here are practical steps you can take before and during a passage to reduce risk and stay functional even when solar activity is high. This isn’t meant to be an exhaustive deep-dive in how to prepare, but as a starting place.
Navigation Systems:
Carry redundant GPS systems – if one goes out or shorts, you have backups.
Get trained on celestial navigation. In addition to being lots of fun, knowing how to use a sextant, compass, paper charts, nautical almanacs, and dead reckoning are how sailors successfully navigated the world for 100s of years. If you plan to do ocean crossings, I’d say it’s a high priority skill to have.
Communication Systems:
Make sure you have HF/shortwave radio, not just VHF or satellite, since some solar storms disrupt satellites and line-of-sight comms.
Ensure antennas and wiring are properly grounded, with good shielding.
And as with anything else, carry as many spare key components that you can in case of shorts or damage (like antenna feed lines).
Power Systems:
Always use properly-rated fuses and circuit breakers in your panels and wiring, and keep plenty of spare fuses aboard. Consider using surge protection to protect your more delicate equipment, like computers.
Ideally, have isolation switches so you can disconnect sensitive electronics quickly.
Make sure your wiring is shielded & properly grounded and routed to avoid induced currents in long runs. If you’re not comfortable doing it yourself, a marine electrician should be able to do an inspection and let you know the status of your boat’s setup.
Satellites & Internet-based Systems:
These you can expect will experience interruptions and/or drop-outs in the event of a geomagnetic storm of significant magnitude. So anything you rely on using these systems should have alternatives / redundancies.
If your weather routing or communication depends on satellites, keep multiple systems aboard (Iridium as well as Starlink, for example) and try to have a non-satellite system, such as SSB + HF email.
As a matter of protocol, too, make it a habit to download and keep offline GRIB / weather data regularly so that if an outage occurs, you have the latest information possible to go off of in your planning.
To wrap up, I want to bring it back to reality that while the occasional drop-out or error in GPS or comms is more likely than a full system collapse, it can’t hurt to plan as if the worst could happen. This way, when you’re out there in the middle of the ocean, you have one less thing to worry about.
Happy Sailing!
Resources: CBS News: May 2024 Solar Storm, NOAA Space Weather Scales
