The first thing my wife asked, the morning we cleared into Cherbourg in 2023, was whether the kids could get their schoolwork uploaded. Not "did we cross safely". Connectivity. That is the modern reality of cruising with a family, and after three seasons working our way down the Atlantic coast on a 38-foot sloop, I have opinions about how to stay online in France without paying through the nose.
This is the practical version. What actually works on a boat, where the signal dies, and what it costs in 2026.
The roaming trap that caught me first
I am British, and like a lot of British sailors I assumed my UK SIM would just work in France the way it did before 2020. It does work. It also charges you for the privilege now.
Free EU roaming for UK customers has been quietly dismantled. By 2026 most of the big four networks (EE, Three, Vodafone) levy a daily roaming surcharge of roughly 2.00 to 2.57 pounds per day to use your home allowance in France. O2 is the outlier that still bundles EU roaming for many customers, but check your specific plan rather than trust the brand. The cause is structural: since Brexit the UK is treated as a non-EU country for wholesale roaming, the same as the United States, so there is no regulated price cap protecting you.
Do the maths on a long cruise. At 2.25 pounds a day, a three-month summer in France is over 200 pounds just in roaming fees, on top of your normal monthly bill. For a fortnight's charter, fine, pay the daily fee and forget about it. For a season, it is money set on fire.
If you are also still untangling the post-Brexit paperwork, I wrote up the wider picture in my notes on the Brexit boat mistakes British sailors still make, and connectivity costs deserve a line on that list.
There is a smaller annoyance hidden in the roaming fine print, too. When your phone latches onto a network, it can pick up a Channel Islands or even a French mast while you think you are still on home soil, and the roaming surcharge fires the moment it does. I have been charged a roaming day fee for a phone that sat in a chart-table drawer all afternoon in a Cherbourg marina, simply because it grabbed a French cell overnight. If you are keeping a UK SIM for emergencies, turn its mobile data off the instant you leave UK waters, not when you remember to.
A French SIM: cheaper, but you need an address (sort of)
The cleanest fix for a long stay is a French prepaid SIM. The market here is genuinely competitive. The disruptor, Free Mobile, built its reputation on cheap data, and prepaid offers from the main carriers (Orange, SFR, Bouygues, Free) routinely give you tens of gigabytes for the price of a few coffees per month.
The snag for a visiting boater is registration. French SIMs require identity verification, and some of the cheapest online-only offers want a French bank card (a carte bancaire) and sometimes a French address to complete sign-up. That rules out the bargain-basement plans for a transient cruiser.
What I do instead: walk into an Orange, SFR or Bouygues shop in a decent-sized town (La Rochelle, Lorient, Brest all have them near the marinas) with my passport. The staff handle the activation in the shop, take a top-up in cash or card, and I walk out with a working number. You pay a little more than the online-only deals, but you skip the address problem entirely.
Tariffs shift constantly, so treat any exact figure I quote as a starting point and check in the shop. The rough shape in 2026: a prepaid data bundle of 20 to 50 GB sits in the 10 to 25 euro range for the month, which undercuts UK roaming by a wide margin over a season.
eSIM: what I actually carry now
The thing that changed my setup was the eSIM. No plastic, no shop, you buy it on your phone and it activates over the air. For a boat that hops between countries (Channel Islands, France, maybe Spain) this is the flexible option.
Orange Holiday Europe is the one most cruisers reach for: a prepaid Europe eSIM covering 40-plus countries with data, calls and texts in one plan, and data-only options that start very low (the entry tier has been around 6 dollars). Travel eSIM resellers go cheaper still, with 1 GB / 7-day plans from under 3 euros. For a two-week trip a few gigabytes on an eSIM day-pass or bundle works out at a tenth of what pay-per-use roaming would cost.
My honest take: I keep a UK SIM live for calls and bank security codes, and run data off either a French prepaid SIM (long stays) or an Orange eSIM (short hops and when I am crossing borders). Dual-SIM phones make this painless.
Where the signal actually drops
Forget the marketing coverage maps. On the water, here is where I lose data, learned the hard way.
The open Channel mid-crossing: expect to lose 4G somewhere past 15 to 20 miles offshore depending on your phone and the network. The Bay of Biscay offshore: nothing, plan for it. This matters more than people admit, because a lot of the modern passage-planning and weather workflow assumes a live connection. If you are timing a Channel crossing weather window, download your GRIBs and forecasts before you slip the lines, not when you are 25 miles out wondering why the app spins.
Inshore is mostly fine. Brittany's ria coast surprised me with how good coverage was even up the rivers, though the granite headlands of the pink granite coast and the deep anchorages behind islands will give you patchy bars. Anchored in a Glenan lagoon you may get a usable 4G signal one minute and nothing the next as the boat swings. The Mediterranean coast is dense with masts and generally strong close in; offshore towards Corsica you will lose it.
A masthead or rail-mounted 4G antenna with a router changes the game if you work afloat. It pulls a usable signal a good few miles further out than a phone in the cabin. I run a cheap weatherproof external antenna feeding a 4G router, and it turned dead anchorages into working ones.
Satellite, and when it earns its keep
A word on the option everyone is suddenly talking about. Low-orbit satellite internet (the Starlink generation of kit) has changed offshore connectivity, and you now see flat dishes bolted to arches in marinas that did not have them two years ago. For a boat genuinely cruising offshore (Biscay, long Channel passages, the run to Corsica) it solves the dead-zone problem outright, and the maritime hardware-plus-subscription cost has come down enough that liveaboards working remotely increasingly justify it.
My honest view for a normal coastal cruiser: it is overkill and overpriced for what most of us do. If you are inshore in France 90 percent of the time, a French SIM and an eSIM cover you for a fraction of the outlay, and you save the satellite money for the genuinely offshore passages where nothing else works. I do not carry it. A friend who works full-time from his boat and crosses oceans does, and for him it is the best money on the vessel. Match the kit to the cruising, not to the marina envy.
A connection plan that actually holds together
Here is the setup I would give a friend arriving from the UK for a full season:
- Keep your UK SIM active but data-off, for banking SMS and the occasional call. Never leave roaming-data on by accident or the surcharge clock starts.
- For stays over a month, get a French prepaid SIM in a carrier shop with your passport. Best value for the data you will burn.
- For short trips or border-hopping, an Orange Holiday eSIM bought before you leave home. Activates on arrival, no shop.
- Download charts, forecasts and any offline material before each passage. BoatMap lets you save a chart area for offline use, which has saved me more than once when the bars dropped 18 miles off Ushant.
- If you work afloat, add an external 4G antenna and router. Two hundred euros of kit that pays for itself in usable anchorages.
One last thing learned the embarrassing way. Public marina wifi is, almost universally, slow and capped. The capitainerie wifi at a busy port in July is shared among a hundred boats all streaming. Treat it as a bonus, never a plan. Your own data is what keeps the boat connected, and after three seasons I would rather pay 20 euros a month for a French SIM than gamble on a marina's overloaded router. If you are still working out the rhythm of when to even be out here, my piece on the French sailing season and when to go where pairs neatly with this one.
