Choosing the first engine for a boat is always a balance between the desire for speed and the need for economy. 3.6 hp outboard motor (often labeled 2.5 kW or 3.5 hp) has become the gold standard for small inflatable boat owners, enabling them to plane confidently on lightweight boats with one person on board, while remaining compact and easy to transport.
Unlike the weaker models at 2-2.5 hp, units with a capacity of 3.6 hp have enough torque to overcome the oncoming current or gusts of wind. Two-stroke The versions are famous for their unpretentiousness to the fuel mixture, while modern four-stroke They're very quiet and cost-effective, but choosing a particular model requires an understanding of the technicalities that we'll talk about later.
It is important to understand that the 3.6 is often a marketing designation or the result of a kilowatt conversion, and the actual power output can vary, yet this class of engine remains the most sought-after among anglers and hunters who value mobility. The critical parameter when buying is not only the declared power, but also the actual traction at low revs, which can vary by up to 20% in different brands.
Technical specifications and capabilities of the class 3.6 hp
Engines with a capacity of about 3.6 horsepower (2.5 kW) are usually based on a single-cylinder unit with a displacement of 40 to 50 cubic centimeters, which provides ease of maintenance and low cost of ownership, and rarely weighs more than 13-15 kg, allowing them to be carried in a backpack bag without attracting the attention of others.
The main advantage of this class is the ability to output light PVC boats up to 3 meters long for planing. When fully loaded (boat + fisherman + equipment), the speed on the water will vary from 18 to 25 km / h. For comparison, lower-power engines are often only able to slowly move the vessel through the water without going into the planning mode, which significantly increases fuel consumption per kilometer of travel.
The cooling system is mostly water-based, forced. impeller (rubber impeller) constantly pumps water through the engine shirt.
⚠️ Warning: Never run the motor on dry or out of water for more than 10-15 seconds – this is guaranteed to lead to melting of the impeller pump and overheating of the glands.It is also worth noting the presence of an emergency shutdown system, which blocks spark formation during engine upheaval.
Two-stroke or four-stroke: the eternal argument
When choosing a 3.6 hp engine, the buyer invariably faces a dilemma: classic 2T or modern 4T. Two-stroke models require a mixture of gasoline and oil in a ratio usually of 1:25 or 1:50, depending on the manufacturer's recommendations. Tohatsu or YamahaThey're simpler in design, lighter in weight, and cheaper to buy.
Four-stroke analogues, by contrast, have a separate oil crankcase, which eliminates the need to mix fuel. They work quieter, consume 20-30% less gasoline and produce cleaner exhaust. However, their weight is often higher and their construction is more difficult, making field repairs almost impossible without a special tool.
If you plan to use the boat infrequently, going fishing a couple of times a month, a two-stroke will be a more rational choice. It is easier to preserve for the winter and easier to "revive" in the spring. For frequent use and long walks, a four-stroke. engine It will provide greater comfort due to the absence of vibrations and the smell of exhaust in the cockpit of the boat.
When storing a two-stroke engine in the off-season, be sure to develop the remains of the fuel mixture from the carburetor, otherwise gasoline will evaporate, and oil will coke the jelly.
Fuel consumption and efficiency of operation
One of the main concerns of owners is how much they eat. For a class of 3.6 hp (2.5 kW), the average fuel consumption is about 0.8 - 1.2 liters per hour when operating at full speed. At cruising speeds, which are about 70-80% of the maximum, the flow rate drops to 0.5-0.7 liters per hour.
The economy depends on the configuration of the carburetor and the quality of the fuel mixture. If the mixture is too rich (a lot of oil), the engine will smoke and lose power, and the candles will be covered with soot. Poor mixture is dangerous to overheat the piston group. The quality of the mixture is adjusted by the screw on the carburetor, but it is better to trust this to the professionals at the first maintenance.
The use of high-quality AI-92 gasoline and specialty outboard oil (labeled TC-W3) is critical. Cheap oils for chainsaws or motorcycles are not suitable, as they are not designed to work in an aqueous environment and can cause failure. knee-bearing.
| Parameter | two-stroke motor | four-stroke engine |
|---|---|---|
| Fuel consumption (max) | ~1.2 l/h | ~0.9 l/h |
| Weight (average) | 13-14 kg | 16-18 kg |
| Noise | High. | Low. |
| Fuel preparation | Mixing with oil | Clean gasoline. |
Fuel economy secrets
In addition to adjusting the carburettor, saving saves the proper loading of the boat. Loading and passengers closer to the transom (but not at the very edge) helps to get to the planing faster, which reduces overall fuel consumption per distance. It is also important to monitor the purity of the lower unit — fouling algae increases resistance.
Compatibility with PVC boats and hinged transverses
The 3.6 hp motors are ideal for inflatable boats ranging in length from 2.8 to 3.6 meters. For shorter vessels (2.0-2.4 m), this thrust can be excessive and dangerous, especially for inexperienced users.
Particular attention should be paid to the type of transom. If your boat has a hinged transom (soft insert), make sure that it is able to withstand the weight of the engine plus dynamic loads when jerking. 3.6 hp engines usually require boats with a hard tampering transom of plywood reinforced with fiberglass or aluminum.
The engine is mounted through the rods.
⚠️ Warning: Before each launch, check the puff of the rods. Vibration on small boats is very strong, and spontaneous spinning of the screws can lead to loss of the engine in the water.It is also recommended to use a safety cable that binds the motor to a fry bolt on a transom.
☑️ Pre-launch checks
break-in and first maintenance
The new 3.6 hp outboard motor requires a mandatory break-in process, which is necessary for grinding the piston group and bearings. The standard procedure takes about 10 motor hours. It is not recommended to give full gas in the first hours; the optimal mode is 50-60% of the maximum power with periodic short-term increases in speed.
The first maintenance (TO-1) is done after the first 10 liters of fuel or 10 hours of motorized production, during which time the oil in the gearbox should be replaced (if it is designed there, in some low-power models it is filled forever) and check the tightening of all threaded joints, and the ignition plug is cleaned from the soak.
Regular maintenance includes lubricating the throttle points, checking the condition of the anodes (if any) and flushing the cooling system with fresh water after use in salt water. engine At times.
To store the engine in the winter, you need to conserve: drain water from the cooling system (purging or tilting), treat the internal cavities of the cylinders with preservative oil and remove it to a dry place. Proper preservation is the key to a successful launch next spring.
Compliance with the breaking in mode increases the life of the piston group of the engine 3.6 hp by 40-50% and ensures stable operation at high revs in the future.
Frequent malfunctions and methods of their elimination
Despite the simplicity of the design, 3.6 hp engines can be troublesome. The most common problem is the lack of spark. The causes can be trivial: a polluted candle, poor contact of a high-voltage tip or a malfunctioning ignition coil. In two-stroke engines, crankshaft glands often die during prolonged storage.
The second most common problem is loss of traction and overheating, which is almost always related to the cooling system, and the garbage, sand, or algae that gets into the water intake block the flow of water.
⚠️ Warning: If the control jet of water has disappeared while driving, immediately shut off the motor. Movement even 30 seconds without cooling can lead to a jamming of the piston.
Carburetor problems, such as unstable idling revs or sneezing, are often solved by cleaning the jellybars and adjusting the mix quality screws. Using old fuel that has been in the tank for more than a month is a guaranteed way to get start problems.
Can I use a 3.6 hp engine on a 4-meter boat?
You can technically start the engine, but it won't work efficiently. A 4-meter boat with a passenger will be too heavy to plane at that power. You'll only move in displacement mode at 5-7 km/h, using fuel inefficiently. For this length, a 5 hp motor is recommended.
Which petrol is better to fill: 92nd or 95th?
For most outboard motors with a capacity of 3.6 hp (especially two-stroke Japanese and Chinese production), the optimal fuel is AI-92 gasoline. The use of 95th gasoline with a high content of alcohols and additives can lead to rapid destruction of rubber carburettor seals and impoverishment of the mixture.
Why is the 3.6 hp engine sometimes called 3.5 or 2.5 kW?
It's a matter of marking and rounding. 1 horsepower is about 0.735 kW. So 3.5 hp is about 2.57 kW. Manufacturers often round up or down values for marketing purposes or depending on certification in a particular region. Technically, they're the same engine class.