A sailing skipper worries about wind. A motorboat skipper worries about fuel, and in France that worry has a particular shape, because the coast and the canals ask completely different questions. Get your range planning right and the motorboat is the easiest possible way to see the country, mast-up, stress-free, on your own timetable. Get it wrong and you are drifting off a Breton headland on the wrong side of a tidal gate with the gauge near empty.
I cross France most years in a planing motor cruiser, and what follows is how I do the sums.
Know your real range, not the brochure range
The first job is to stop trusting the brochure. Builders quote range at a flat cruising speed in calm water with a clean hull and half tanks. Real life is none of those things. Wind, sea state, a foul bottom, a full boat and a strong foul tide all eat your range, and on a planing boat the penalty for pushing speed is brutal.
Work out your boat's litres-per-hour at two or three speeds, not one. A typical fast planing cruiser might burn modestly at displacement speed, then double or triple that the moment it climbs onto the plane, so the difference between a relaxed 8 knots and a hurried 20 knots can halve your range. Then apply a reserve. I plan to arrive with 20 percent in the tank as a hard floor, and I treat 30 percent as the point where I stop and bunker rather than push on. On a tidal coast that reserve is not optional, because if you miss a gate you may have to punch foul tide or hold station for hours, and both burn fuel you had not budgeted.
The coast: tides set the timetable, fuel sets the legs
On the Channel and Atlantic coasts the brutal truth is that the tide runs the day, not your throttle. The Alderney Race and the Raz de Sein run hard enough to stop a slow boat dead, so you plan your legs around slack water and fair tide, and your fuel plan has to survive a missed gate. That means bunkering before a tidal passage, not after it.
Fuel berths are not on every quay, so you cannot assume you will top up at the next stop. Plan the bunkering, do not improvise it. I keep a running list of which ports have an accessible fuel pontoon and what hours it keeps, because plenty close at lunchtime, on Sundays, and out of season. The where-and-when of buying diesel afloat is laid out in boat fuel France where to bunker, and it is the single most useful thing to read before a coastal motor passage.
On price, expect marina diesel on the coast to track well above road prices, because you are paying for the convenience of the pontoon. Budget figures move with the oil market, but coastal marina diesel has commonly sat somewhere around 1.70 to 2.00 euros a litre in the 2025-2026 seasons, and remote or island fuel berths charge more. Carry that number into your planning and the cost of choosing 20 knots over 8 stops being abstract very quickly.
A word on red diesel
Visiting boats often ask about the cheaper duty rate. The rules for marked or reduced-duty diesel for private pleasure craft are not the same as the UK regime and have tightened, so do not assume you can fill with red and pay the low rate as you might at home. Check the current position before you bunker, keep your receipts, and if you arrived with red diesel in the tank from the UK, understand that the propulsion fuel rules differ across the Channel. This is a paperwork question as much as a fuel one, and it sits alongside the wider arrivals admin in the sailing to France after Brexit checklist, which is worth a read for any visiting boat regardless of rig.
The canals: a different fuel world entirely
Take the motorboat inland and the whole problem changes. Speed is capped, commonly around 6 to 8 km/h on the canals, so you are at displacement speed all day and your fuel burn drops to a fraction of coastal cruising. The range question stops being about distance and becomes about where you can physically fill up, because canal fuel points are sparse and far apart.
This is where planning matters most. You can motor for days without passing a fuel berth, so you carry jerry cans, you fill whenever you get the chance even if the tank is half full, and you note the next opportunity before you leave the last one. The locations of diesel, water and pump-out on the inland network are mapped out in French waterways diesel water pumpout, and treating that as gospel rather than guesswork is how you avoid a long, embarrassing wait for a fuel barge.
The motorboat's other big advantage inland is that it crosses France mast-up. A motor cruiser slides under the bridges where a sailing yacht has to unstep its mast, because the canal air-draft ceiling sits around 3.5 m and a low-profile motorboat clears it with the antennas folded. The full route, the locks and the gauge are in crossing France by canal from the Channel to the Med, and for a motorboat it is one of the great inland passages of Europe precisely because the fuel and air-draft problems that torment sailors barely touch you.
Speed, sea state and the real fuel curve
The hardest habit for a new motorboat owner to break is treating speed as free. On a planing hull it is anything but. There is a hump-speed band, the point where the boat is trying to climb onto the plane but has not yet, where fuel burn is at its very worst for the distance covered. Push through to a clean planing speed and the economy improves again, but the most economical cruise is usually either a relaxed displacement speed well below the hump or a steady planing speed comfortably above it. The expensive place to live is in between, and a lot of skippers sit there without realising.
Sea state moves the whole curve. Into a head sea and a foul tide a planing boat may not get onto the plane at all without burning hard, so you either accept the fuel cost or slow to displacement speed and let the gate pass you. That decision is a fuel decision and a tide decision at the same time, which is why coastal motorboating in France is really an exercise in reading both together. The boat that arrives with fuel in hand is the one whose skipper slowed down when the sea told him to.
Keep a simple log of litres burned against engine hours and speed for your own boat, because the manufacturer's figures will flatter you and your real numbers are the only ones worth planning with. After a season you will know your range at each speed to within a few miles, and that knowledge is what lets you commit to a long coastal leg without anxiety.
The numbers I plan around
A handful of figures frame every motorboat passage in France:
- Plan to arrive with at least 20 percent fuel; stop and bunker at 30 percent before a tidal gate.
- Climbing onto the plane can double or triple your litres-per-hour against displacement speed.
- Coastal marina diesel has commonly run around 1.70 to 2.00 euros a litre in 2025-2026, above road prices.
- Canal speed limits sit around 6 to 8 km/h, slashing fuel burn but stretching the gap between fuel points.
- The canal air-draft ceiling is roughly 3.5 m, which a motorboat clears mast-up where a yacht cannot.
Making the motorboat work for you
The motorboat is the most flexible way to cruise France, but it rewards the skipper who treats fuel as seriously as a sailor treats wind. On the coast, bunker before the tidal gates, never after, and respect the speed-versus-range curve. Inland, fill at every chance and map the fuel points before you cast off. Keep your receipts for the diesel duty question, watch the marina price against the road price, and build a reserve you never spend.
Do that and you get the best of France with none of the rig hassle: under the bridges with the mast at home, across the gates with fuel in hand, and into the harbour at a time of your choosing rather than the tide's. The throttle gives you that freedom. The fuel plan is what lets you keep it.
