Before you cast off and attempt to re-enact Master and Commander across the Sir Francis Drake Channel, we need to have a brief chat about diesel. Burning fuel is not something to be concerned about but treat it like an afterthought and your end-of-charter trip to the fuel dock might take you by surprise.
Here is how your propulsion engines and your generator actually consume fuel; and how to avoid losing all your beer money at the fuel dock.
Your sailboat—whether it’s a monohull or a floating condo-catamaran—is powered by honest, hardworking diesel engines. At Conch all our propulsion engines are either Yanmar or Volvo Penta. They consume fuel measured in gallons per hour (GPH), be aware fuel burn is exponential, not linear.
• The Optimal Range (2,000–2,200 RPM): Settle the throttles here. A standard 45-to-60-horsepower diesel will sip a modest 0.8 to 1.2 GPH. The boat hums along comfortably, the tea stays in the mug, and all is right with the world.
• The "I’m Late for Happy Hour at Willy T’s" Mistake (2,500RPM+): Ramming the levers to the stops will not make a displacement hull plane, no matter how much you wish it. You’ll potentially gain an additional knot of boat speed while increasing your fuel burn by over 50%!
• The Multihull Multiplier: If you are on a catamaran, remember you have two engines down there. If you insist on motoring into a 20-knot headwind because you didn’t want to hoist the mainsail, be ready for the wrath of the fuel dock on return.
Your genset—always an Onan or a Northern Lights—behaves on an entirely different set of rules. Unlike the main engines, a marine generator does not rev up and down with a throttle. It sits down in the lazarette spinning at a dead-steady 1,800 RPM (to give you North American 60Hz current) whether you are charging an iPhone or trying to turn the master cabin into a meat locker.
• Load Dictates the Burn: Because the engine speed is locked, your fuel burn is determined solely by electrical load.
• The Reality: Running a quiet trickle to top up house batteries and run the fridge? That genset is barely working, sipping around 0.3 to 0.4 GPH.
• The Arctic Fantasy: The moment your crew demands all three air-conditioning compressors fire up simultaneously while someone runs a hairdryer and the electric galley stove, the governor opens the diesel taps wide to keep that alternator spinning under the strain. Now you're burning 0.7 to 0.9 GPH.
Back home in the States or Canada, you pull your truck up to a pump and complain when diesel hits four bucks. Down here, expect to pay anywhere from $6.00-$7.00+ per US gallon at the gas station. Of course, like anywhere, marinas charge a premium above this for serving diesel on a dock. Before you accuse the dockmaster of privateering, understand the brutal logistics of island life
1. It Arrives on a Ship, Not a Pipeline: Every solitary drop of fuel in the BVI is refined somewhere else and hauled across the ocean on a tanker. Tankers require crews, bunker fuel, insurance, and hazard clearance. By the time that diesel enters a holding tank on Tortola or Virgin Gorda, it has racked up a rather impressive travel tab.
2. His Majesty’s Customs & Tariffs: The BVI government levies customs duties, environmental levies, and wharfage fees on imported petroleum products. Small island nations have infrastructure to fund, and fuel imports are a prime source of revenue.
3. Marine Infrastructure in Saltwater: Saltwater eats metal, pumps, concrete, and wiring for breakfast. Maintaining high-capacity fuel jetties, environmental spill containment, and commercial filtration in an archipelago isn’t cheap. That overhead gets baked into every gallon.
Let’s run the numbers for a standard, realistic scenario. You’ve chartered a modern 42-to-45-foot catamaran equipped with twin 45 HP Yanmar JH or a D2-50F Volvo Penta engines and an 9kW Northern Lights or MDKDN Cummins Onan generator. You have seven nights aboard. You aren't crossing the Atlantic; you’re pottering between Tortola, Norman Island, Virgin Gorda, and Jost Van Dyke.
The Operational Parameters:
• Duration: 7 nights / 8 days
• Main Engines: 2 hours per day (dropping mooring lines, picking up anchor, anchoring drill, maneuvering into tight bays).
• Generator: 10 hours per day (running overnight AC so your crew doesn’t stage a mutiny over tropical humidity – 10pm to 8am).
• Current Marina Fuel Rate: Let's call it a conservative $6.99 per gallon (current rate at Fort Burt Marina fuel dock – for those of you that already know Liz, she hasn’t been here to update the rate on the pump yet!).
The cold, hard ledger
| Equipment | Daily Operating Hours | Average Burn Rate | Daily Consumption | 7-Night Charter Total |
| Twin Engines (Combined | 2.0 hours | ~2.0 GPH (both at a disciplined 2,200 RPM) | 4.0 gallons | 28.0 gallons |
| Generator (9kw Genset) | 10.0 hours | ~0.75 GPH (moderate AC load) | 7.5 gallons | 52.5 gallons |
| Daily Vessel Total | - | - | 11.5 gallons | 80.5 gallons |
The Damage:
Engines: 28 gallons×$6.99/gallon=$195.72
Generator: 52.5 gallons×$6.99/gallon=$366.98
Total: 80.5 gallons×$6.99/gallon=$562.70
Notice anything interesting? Over 65% of your fuel bill wasn’t spent moving the boat. It was burned while you were fast asleep, running an air-conditioner at an empty anchorage.
How to Slash Your Fuel Bill (and Look Competent Doing It)
If you wish to keep your beer money for beer — adhere to four basic seamanship principles.
1. Lock Your Throttles at 2,200 RPM There is an intoxicating urge among charter skippers to push the levers to 2,500 RPM because they want to beat the crowd to the mooring field at Cooper Island. Not worth it. Above 2,200 RPM, the ratio of speed to fuel burned is no longer favourable. Throttle back, breathe the sea air, and let the diesels purr.
2. Remember You Rented a Sailboat The Sir Francis Drake Channel is blessed with 15 to 20 knots of predictable, glorious easterly trade winds almost every day of the charter season. Yet every afternoon, we look out from our dock and watch bareboats motoring directly into 18 knots of breeze with the mainsail neatly packed away under its sail cover like a museum exhibit. Hoist the canvas. Shut down the engines. A beam reach across to The Baths under full sail costs exactly zero dollars in fuel and makes you look like you know what you’re doing.
3. Let Solar Run the Daylight Shift All Conch Charters catamarans carry an array of solar panels atop the bimini or coachroof. During peak sun, those panels produce ample wattage to keep your house batteries floating, run the 12V galley refrigeration, and charge every smartphone aboard. Ask the sales team about the solar panels fitted on the boat you booked or are looking to book.
4. Deploy Breeze Boosters and Rig for Natural Air Before you reflexively hit the generator toggle at 9:00 PM, look at your surroundings. You are moored head-to-wind in the Caribbean trade winds. Rig a breeze booster or canvas windscoop over the forward deck hatches. Open the overhead hatches (dog down the side ports if there's spray) and let the trade winds funnel down into the cabins. Switch on the low-draw 12V cabin fans over the berths. You’ll get cool, moving ocean air, dead silence in the anchorage, and zero hours clocked on the genset meter. Save the generator and the AC for those rare windless nights or the sticky heat of July and August.
When you bring the vessel back to the marina at the end of the week, like always we will bring you in. If you need to refuel during your charter, take your time coming alongside the fuel pontoon, have your fenders at dock level, your lines led through the fairleads, and an alert crew standing by. And for the love of all things nautical: ensure the nozzle goes into the deck plate stamped DIESEL.
Every season, an ambitious soul fills the holding tanks with twenty gallons of low-sulfur diesel which are normally painted black. At that point, your fuel bill will be the least of your financial worries.
We hope you found this informative and we hope even more that the price of diesel goes back to where it used to be in the not too distant future!