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 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.
Gear ratio
The gear ratio describes how fast the propeller of the outboard motor rotates relative to the speed of rotation of its shaft. For example, a gear ratio of 2 means that for each revolution of the shaft, the screw, in turn, makes two revolutions (that is, it rotates twice as fast). In modern outboard motors, this parameter, in fact, is purely reference, because. the practical characteristics of the unit (power, traction, etc.) depend on many design features and are practically not related to the gear ratio.
Launch type
The starting method provided for in the design of a gasoline outboard motor (see "Engine type"). In any such engine, the shaft must be rotated to start; this crank provides the supply of the first portion of fuel and a spark of ignition, after which the engine continues to work independently. Starting systems differ based on the manner in which said cranking is carried out.
— Manual. As the name implies, the initial impulse in such systems is provided by the operator himself manually. The most popular option is a “starter” with a rope, a jerk for which turns the engine shaft; but other launch methods may be envisaged. Anyway, manual start is convenient primarily due to the absence of a battery and a starter. This, firstly, has a positive effect on weight and dimensions, and secondly, it gives a guarantee against unpleasant situations when a dead battery does not allow the engine to be started. On the other hand, the procedure itself may require significant muscular effort, and even having experience with such systems does not guarantee start from the first jerk. Manual "starters" are typical for low-power motors, which are relatively easy to crank.
— Electric. With this method of starting, the necessary impulse is provided by
a starter — a special electric motor powered by a battery. The main advantage of electric "starters" in comparison with manual ones is convenience — there is no need to scroll the engine manually,
...just turn the key or press the button. On the other hand, such systems are more complex, take up more space and are noticeably more expensive. In addition, during the operation of the motor, you have, among other things, to monitor the condition of the battery — if it sits down, starting the motor will become impossible. And you will either have to change / charge the battery, or look for an external source of energy like a starter boats, having such equipment in the vicinity can be a serious problem). Therefore, a purely electric type of start is found in powerful motors (from 100 hp), for which the manual procedure is practically not applicable.
— Manual/electric. Models that combine both of the methods described above. Usually, such motors are equipped with their own starters and are regularly started electrically, and the manual “starter” plays the role of insurance in case of failures in the main system. Such systems combine the advantages of both options, but they are quite rare. This is not only due to the high price, but also because the combined starting method is suitable for a rather specific category of outboard motors: large enough to accommodate a starter with a battery, and at the same time not so heavy as to create problems during manual starting. . Therefore, this option is rare, mainly in models for 20 – 40 hp.Weight
The total weight of the outboard motor. This parameter is indicated, usually, only for the unit itself, without taking into account the fuel in the tank and the tank itself (if it is external, see "Fuel tank"), as well as additional equipment. Motor weight data can be useful in order to estimate the overall balance of the boat and the change in its payload capacity.
