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Every liter of fuel on board translates to range, but it also comes with a cost that can quickly add up when bad habits take hold at the helm. Excessive speed, a fouled hull, or inefficient engine use?several factors account for the sometimes significant differences observed between two comparable boats. Here are eight factors to consider to help reduce your fuel costs.
Trim: an adjustment that changes drag
The trim system controls the angle of the outboard motor or the base of a Z-drive motor. Its function is not limited to enhancing the comfort of the ride. It affects the boat?s trim, the hull?s wetted surface area, and thus its resistance to forward motion.
When planing, the engine is usually kept in the low position to minimize nose-diving. Once the boat is planing, the driver can gradually raise the trim until the boat glides more smoothly.
When the bow lifts slightly out of the water, drag decreases. Conversely, a trim that is too negative keeps the hull pressed against the surface. A trim that is too high makes the boat unstable and also reduces efficiency.
The automatic trim systems offered by some engine manufacturers now make it possible to continuously optimize this setting based on engine RPM and airspeed.
The cleanliness of the hull remains a major factor
Boaters often underestimate the impact of underwater fouling. Yet just a few weeks at anchor or docked is enough for algae, shellfish, and various other deposits to begin to form.
This additional roughness significantly increases hydrodynamic drag. As a result, the engine must work harder to maintain the same speed. Regular application of antifouling paint suitable for the area of navigation remains the best form of protection.
A clean base is just as important as the shell
While the hull often gets the most attention, the engine mount deserves just as much attention.
A buildup of shellfish or marine growth around the propeller disrupts water flow and reduces propulsive efficiency. Losses in speed can become significant. During dry-docking operations, inspection of the propeller shaft, cooling water intakes, and propeller must be part of the routine checks.
Adjust the cruising speed
On a motorboat, reducing speed by just a few knots can often lead to significant fuel savings. Hydrodynamic drag increases rapidly with speed. The difference in fuel consumption between cruising at high speed and at a slightly slower pace can amount to several dozen liters over the course of a day?s sailing.
Lighten the boat and distribute the load properly
Every kilogram carried must be propelled. Unnecessarily filled water tanks, unused gear on board, or rarely used equipment increase the overall displacement. Weight distribution also plays an important role. An overload at the stern accentuates the bow rise during planing and hinders the boat?s ability to plane.
A well-balanced boat reaches its optimal cruising trim more easily and places less strain on its engine.
Maintain the engine to preserve its performance
A poorly maintained engine consumes more fuel to produce the same power. Routine maintenance tasks include checking fuel filters, spark plugs on gasoline engines, lubricants, and the fuel system.
Adhering to the manufacturer's maintenance schedule also helps minimize the risk of breakdowns at sea?an issue that goes far beyond the mere question of fuel.
Check the propeller and drive smoothly
The propeller is the final link in the propulsion chain. A warped blade, a damaged leading edge, or an improper pitch results in an immediate loss of efficiency. The engine may then operate outside its optimal range, leading to increased fuel consumption.
Driving style also plays a role. Sudden acceleration, constant changes in engine speed, and long periods of idling unnecessarily increase fuel consumption. Conversely, driving at a steady pace, with gradual acceleration and a consistent speed, allows for more efficient use of the vehicle?s available energy.
For many boaters, the biggest savings don?t require any investment. Properly adjusted trim, a clean hull, a propeller in good condition, and an appropriate cruising speed are often enough to significantly reduce fuel consumption. These simple steps also increase your boat?s range and operating radius, while saving you money.
