Choosing the right one boat-engine For an inflatable craft, it's not just about buying equipment, it's about finding the optimal balance between power, weight and safety. Many beginners make the mistake of buying overpowered or too weak equipment, leading to fuel overruns or an inability to plane.
In this article, we will discuss in detail the technical nuances that affect the speed and handling of your PVC boat. lower unit It affects the efficiency of the screw and why electric motors They are becoming a popular alternative to gasoline units in certain operating conditions.
Inflatable boats have their own design features that impose limitations on engine choice, and it is important to understand the difference between transom mounts and hinged models to avoid damage to cylinders or loss of control on the water.
Key parameters of power selection
The first thing to decide on is the purpose of your boat, and for a quiet fishing on the lake and for active water tourism, you need completely different specifications. Engine power directly determines whether the boat can go to plane with full load.
There is a simple formula for calculating: for every 25-30 kg of total weight (boat + motor + equipment + passengers), 1 horsepower is required. However, for inflatable boats it is critically important not to exceed the maximum permissible power specified by the manufacturer in the product passport.
Let’s look at the main classes of PVC engines:
- 🚤 2-5 hp - Ideal for small single boats up to 3 meters long, speed up to 10 km / h, exit to planing is possible only with one person.
- 🚤 6-9.9 hp The “golden mean” for boats 3-3.5 meters long, confident planing with two passengers, often have a power limiter.
- 🚤 10-15 hp. - for heavy complexes with a length of 3.6 meters, allow you to develop high speed and tow a water skier.
When choosing, you should also pay attention to the presence of a system. electronic ignitionIt is a stable launch system, even after long downtime, and for high-performance models, reverse and neutral transmission are a safety requirement.
Two-stroke or four-stroke: the eternal dilemma
The question of choice two-stroke and four-stroke Two-strokes are traditionally lighter, easier to maintain and cheaper, but they require a fuel mix and produce more noise.
Four-stroke engines, by contrast, are more economical, quieter and more environmentally friendly, running on clean gasoline, making it easier to refuel in the field, but they are much heavier, which is critical for light inflatable boats, where every kilogram on the transom affects the trim.
Comparison of specifications will help to make the right choice:
| Parameter | two-stroke motor | four-stroke engine |
|---|---|---|
| Weight. | Easy, 20-30%. | Heavyer, more complex construction |
| Fuel consumption | Above (mixture with butter) | Down 30-40% |
| Noise | High. | Low, smooth sound. |
| Transportation | In any situation | Strictly vertically |
Can I use a four-stroke motor on a small boat?
Yes, but you need to be careful about the differentiation, and a heavy motor can bury the bow of the boat in the water, which will lead to a flood, in such cases, it is recommended to put passengers closer to the nose or use inflatable keels for additional buoyancy.
If you are planning long transitions and appreciate comfort, four-stroke It's a better solution. For short-term trips for an hour or two or for use as a spare engine, the two-stroke model will be more practical.
Features of electric motors for PVC
In recent years electric motors They're popular with inflatable boat owners, they're silent, they don't produce exhaust gases, they don't require complicated maintenance, and they're the perfect choice for trolling or cruising in protected areas where ICE noise is not allowed.
The main choice of electric motor is thrust, measured in pounds (lbs). To move an inflatable boat with one or two passengers, 30-40 lbs is usually enough. It is important to consider that the real speed depends on the capacity of the battery.
Advantages of electric traction:
- 🔋 Absence of vibrations, which is especially important for sensitive electronics of sonars.
- 🔋 The ability to instantly start and stop without warming up.
- 🔋 Compact and easy installation on the transom.
Use AGM or deep-discharge GEL traction batteries. The car's starter batteries will quickly fail when running at long, low speeds.
But remember, you have to be dependent on battery power, and if you go far from the shore and the charge runs out, paddles with a heavy electric motor on the transom will be extremely difficult, so it's a must-have for you to plan your route with a range.
The length of the lower unit and the set on the transom
Proper installation of the motor on boat-sweeper The key here is the length of the lower unit (legs), and inflatable boats are most often used motors with a short leg (S - 381 mm) or ultrashort (XS - 300-330 mm).
If the lower unit is too long, the water resistance will increase, causing the engine to drop and overheat, and if it is too short, the propeller will capture air ("cavitation"), especially on corners, which can lead to loss of control.
⚠️ Warning: When installing the motor, make sure that the anti-cavitation plate is on the same level as the bottom edge of the boat or 1-2 cm lower, this will ensure the correct flow of water to the propeller.
On inflatable boats, the transom often has a soft skin, so it is recommended to use special plastic or rubber linings between the metal presses of the motor and the PVC fabric to avoid damage when vibrating.
☑️ Checking the engine installation
Security and GIM regulations
Small boats require certain rules to be followed, and even if your boat does not require registration (weighing less than 200 kg or engine power less than 8 kW/10 hp depending on the year of manufacture and type), safety should not be neglected.
Always use a safety cable (check), which is attached to the life jacket of the driver. In the event of a person falling overboard, the cable will pull the check, and the engine will instantly stop, preventing the screw from hitting.
The main requirements for equipment:
- 🛟 Life jackets by the number of people on board.
- 🛟 A scoop (scoop) to remove water from the cockpit.
- 🛟 Anchor and anchor shaft corresponding to the depths of the navigation region.
- 🛟 The PVC repair kit (remap) should always be in the boat.
The lack of a life jacket is the most common cause of tragic outcomes on the water, even in calm weather.
It is also worth remembering that the control of a boat with an engine of more than 5 hp formally requires the right to operate a small vessel of category "M". Ignoring this rule can lead to fines from the inspectors of the GIMS.
Service and preparation for the season
And boat-engine It has been in service for a long time and does not let you down far from the shore, you need regular maintenance. After each trip, especially in salt water or in muddy waters, it is recommended to wash the cooling system with fresh water.
For two-stroke engines, it is important to prepare the fuel mixture correctly. The proportions of oil and gasoline (usually 1:25 or 1:50) must be strictly observed. The use of poor-quality oil or old gasoline leads to the coking of the piston group and spark plugs.
The order of conservation for the winter:1. Dispose of the fuel residue from the tank.
2. Start the engine and develop the remaining gasoline in the carburetor.
3. twist the candle, pour 5-10 ml of engine oil into the cylinder.
4. Rotate the starter several times to distribute the oil.
5. Place the candle back and remove the motor to a dry place.
⚠️ Warning: Never keep a full tank of gasoline engine indoors. Fuel vapors are explosive and toxic. The tank must be empty or, conversely, fully filled (without air) when adding a stabilizer, but the former option is safer for garage storage.
Regular lubrication of the points of rotation (gas handle, rummel, tilt mechanism) with lithium lubrication will prevent corrosion and jamming of mechanisms. Pay special attention to the condition of the lower unit: the chips of the paint must be painted immediately to avoid corrosion of the aluminum alloy.
FAQ: Frequently asked questions
What engine to choose for a boat with a length of 3.2 meters?
For a boat with a length of 3.2 meters, the optimal choice will be a motor with a capacity of 5-8 hp This is enough for a confident exit to planing with one or two adult passengers. If the boat has an inflatable keel and a hard floor, you can consider the option up to 9.9 hp.
Do I need to register a boat with a 5 hp engine?
According to the current legislation of the Russian Federation, boats with a mass of less than 200 kg and an engine power of up to 8 kW (about 10.8 hp) are subject to registration. However, the rules may change, and it is always worth checking the current information at the local branch of the GIMS, since the total weight of the boat in charge is taken into account.
Why does the engine stop at high speeds?
Most often, the cause lies in a violation of the fuel supply: a carburetor jetty is clogged, the fuel filter is contaminated or the tightness of the fuel system (air suction) is impaired, and the problem may be in the spark plug or cooling system (overheating).
Can I carry the motor in the trunk of a car?
Yes, you can, but only in a horizontal position and strictly on a certain side (usually it is the right side where there is no exhaust exhaust exhaust, or at an angle of 45 degrees). Be sure to drain the remaining fuel from the carburetor before transportation, so as not to fill the cabin with gasoline vapors.