Maximum power
The maximum operating power of the outboard motor, expressed in kilowatts.
The practical value of motor power is described in detail in “Maximum power" is higher. Here we note that the kilowatt (derivative of watt) is just one of the units of power used in fact along with horsepower (hp); 1 HP ≈ 735 W (0.735 kW). Watts are considered the traditional unit for electric motors (see "Engine Type"), but for a number of reasons, outboard motor manufacturers use this designation for gasoline models as well.
Maximum revolutions
The highest shaft speed that the outboard motor is capable of developing.
Theoretically, the speed of rotation of the propeller (or turbine — see "Motor type") depends on the engine speed, and, accordingly, the speed that the boat is capable of developing. However, in addition to this indicator, many other factors also affect the performance of the motor — engine power (see above), gear ratio (see below), propeller design, etc. As a result, situations are quite normal when a more powerful and high-speed motor has lower revolutions than the weaker one. Therefore, this parameter is, in fact, a reference one, and has almost no practical value when choosing. Unless it can be noted that high-speed motors are more susceptible to noise and vibration than low-speed ones; however, this moment can be compensated by the use of various technical tricks.
Capacity
The working volume of a gasoline outboard engine (see "Engine type"). This term usually means the total working volume of the cylinders.
The larger this value, the higher the motor power, usually (see the relevant paragraph). At the same time, with an increase in the working volume, fuel consumption, weight and dimensions of the unit also increase; and power depends not only on this indicator, but also on a number of other factors — ranging from the number of strokes (see "Engine duty cycle") or the presence of turbocharging (see below) and ending with specific design features. Therefore, situations are not excluded when a smaller engine will have more power, and vice versa.
Piston diameter
The diameter of a single piston in a gasoline (see "Engine type") outboard motor. In most cases, this parameter is purely reference; situations where data on the piston diameter is really needed are extremely rare — usually during the repair or maintenance of the engine.
Piston stroke
The working stroke is the distance between the two extreme positions of the piston in a gasoline (see "Engine type") outboard motor. In most cases, this parameter is purely reference; situations where such data is really needed are extremely rare — usually during the repair or maintenance of the engine.
Exhaust system
The design of the exhaust system in a gasoline outboard motor (see “Engine type”), more precisely, the method of exhaust gases used in this system.
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Above the screw. This category includes two types of engines. The simplest option is when exhaust gases are emitted directly into the air. Such systems are extremely simple and cheap, but the exhaust can create a noticeable inconvenience for people in the boat (not only because of the gases, but also because of the rather high noise level); therefore, they are found only in the simplest outboard motors, and even then quite rarely. A more common option is to release exhaust gases into the water above the propeller (most often through the so-called anti-cavitation plate — a flat ledge above the propeller). Such systems are more comfortable than "air" ones, while they are simpler and cheaper than propeller exhaust (see below), although they are still considered less technically advanced.
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Through the screw. In systems of this type, the exhaust is led into the water directly through the propeller hub; in fact, the position of the exhaust pipe coincides with the axis of rotation. This reduces the noise level compared to systems using exhaust over the propeller, and also slightly increases power and traction characteristics. The downside of these advantages is the design complexity and, accordingly, the high cost.
Generator system
Possibility to use a petrol engine generator(see "Engine type") to power an external load.
The generator is an indispensable element in the design of any petrol engine — it is responsible for creating the spark necessary for ignition. However, not every outboard motor has the ability to power an external load from this generator — therefore, if such an opportunity is important to you, you should choose a model where it is directly stated. And
the generator system can come in handy, first of all, if you plan to use additional equipment on the boat — power from the generator is in a number of ways more convenient than from autonomous batteries, and it is for it that many navigation systems, echolocation, radio communications and other instruments and equipment are made . In addition, if necessary, devices outside the boat can also be powered from the generator — for example, a starting charger for a car.
Power source
The supply voltage supplied by the generator system installed in the outboard motor.
Almost all such systems work with a voltage of 12 V — this is a standard widely used in modern automotive and water technology, it is under it that the electrical systems of the engines themselves, and electronic devices for cars and boats are made. There are practically no exceptions to this rule.
Maximum current strength
The highest current that the generator system installed in the outboard engine is capable of delivering (see above). The characteristics of the load that can be connected to the generator depend on this indicator: its total current consumption should not be higher than the maximum current of the generator, otherwise the latter will work with overload, which is fraught with malfunctions and even accidents. Also, this information is useful if you plan to use the generator to charge batteries (car or boat): each battery has its own charging current, and the power source must match them.
