Choosing a power unit for a 320 centimeter inflatable vessel is always a compromise between speed, payload and budget, and owners often face the dilemma of taking the lowest possible option to save or adding power to plane with the passenger. The best choice It depends on how you plan to use the boat: for quiet fishing in calm or for quick transitions to the reservoir.
Wrongly selected engine It can turn the pleasure of cruising into a complete disappointment, whether it is an inability to planing or excessive fuel consumption. In this article, we will discuss in detail the technical nuances that will help you make an informed decision. For a PVC boat 320 cm, a critical parameter is not only horsepower, but also the weight of the engine, since at a short length of the hull, each extra kilogram on the transom affects differentiation.
There are many factors, from the type of screw to the height of the lower unit, that together determine the final speed. Let's look at them sequentially to eliminate errors in the purchase. Understanding the physics of the process will allow you to not overpay for unnecessary specifications and get exactly what you need for your operating conditions.
Calculation of the optimal engine power
The first thing to start with is to study the plate on the transom of your boat, which indicates the maximum allowable powerFor a length of 320 cm, manufacturers usually recommend a range of 5 to 10 horsepower, but the real picture depends on the width of the bottom and the presence of an inflatable keel. If you have a narrow boat without a hard floor, a powerful engine can simply bury the stern, instead of pushing the boat forward.
To go into the regime planing With one adult and a minimum load is usually enough 5 hp However, if you plan to take a passenger, equipment or anchor equipment, 5 forces may not be enough for confident acceleration.
It is important to bear in mind that capacity It doesn't have to be the limit of everything. An engine that's running at its limits wears out faster and consumes more fuel. It's better to have a small margin that allows you to feel confident in a headwind or a strong wind.
- 🚤 5 hp - Ideal for solo fishing in quiet weather and shallow water.
- 🚤 8-9.9bhp. - a golden mean for two people and access to planing with cargo.
- 🚤 10+ hp - excessive for most models 320 cm, may require strengthening of the transom.
- 🚤 Electric motors - suitable only for moving in displacement mode over short distances.
⚠️ Warning: Installing a motor above the boat recommended by the manufacturer can cause transax deformation, loss of stability and, as a result, to tip over the vessel.
Two-stroke or four-stroke: what to choose
In the small power segment, relevant for boats 320 cm, the choice between two-stroke and four-stroke Two-strokes are traditionally lighter, which is a critical parameter for carrying a boat by one person, and the difference in weight can reach 10-15 kg, which significantly affects the ease of transportation and installation.
Four-stroke engines, in turn, are quieter, idle-stable and cost-effective, and do not require a fuel mix, making it easier for beginners to operate. dimensions and weight They often make them less attractive to owners of small PVC boats, where every kilogram counts.
If you value the acceleration dynamics and the ability to quickly transport the engine in the trunk in any position, a two-stroke unit will be preferable. For those who spend a lot of time on the water and appreciate comfort, silence and no smoke, a four-stroke will be the best choice, despite its weight.
It is also worth mentioning eco-friendlinessFour-stroke engines burn cleaner fuel, which is especially important in protected waters where restrictions on the use of two-stroke technology may apply. In some regions, the use of motors without a catalytic converter may be limited.
Motor weight and impact on driving performance
The weight of the power unit is not just a number in the passport, but a factor that directly affects the weight of the power unit. differentiator For a 320 cm PVC structure, the overweight on the transom makes the stern sink deeper, increasing the water resistance, which causes the boat to go worse and lose at top speed.
The optimum engine weight for this length of the body is usually in the range of 20 to 27 kg. Heavy models require either a very rigid inflatable floor or the installation of additional buoyancy cylinders on the stern. Light models up to 22 kg allow you to maintain balancing even at minimal load.
When choosing, pay attention not only to dry weight, but also to the weight with a full tank and oil. Tanking the boat It's shifting backwards, and if the engine is too heavy, you'll have to put passengers or load things strictly on your nose to level the boat, which creates discomfort and reduces safety.
There is a belief that a heavy motor is better at quenching vibration. antivibration And the balance of the shafts is more important than the total mass, and a lightweight but well-balanced motor will be more comfortable than a heavy but vibrating motor.
lower unit and the choice of propeller
The length of the lower unit (motor legs) should correspond to the height of the transom of your boat. The standard for most PVC boats is 320 cm. short leg (S)The installation of a long leg (L) motor will require a transom extension, which is not always technologically justified and safe.
A propeller is the "transmission" of your motor. Standard aluminum propellers are suitable for most tasks, but their geometry (step and diameter) greatly affects traction. For heavy loads and full load plane, reduced pitch screws are often recommended, which give better traction at low revs.
| Parameter | Standard screw. | The Traction Rotor (Low Thrust) | Speed rotor |
|---|---|---|---|
| Appointment | Universal. | Heavy boats, trolling | Maximum speed |
| Step. | Medium. | Small. | Big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big big |
| Materials | aluminum | Aluminum/Composite | Stainless steel/aluminum |
| The effect | Balance of traction and speed | Improved acceleration | High max speed. |
If you notice that the engine is not developing maximum speed under load (does not twist), most likely, the pitch of the screw is too large for your boat. Conversely, if the engine is howling at full speed, but the boat is not accelerating, the screw is "empty", and its pitch should be increased. The propeller allows you to unlock the potential of the engine by 10-15% more efficiently.
Fuel efficiency and range
For small boats, such as 320 cm, the fuel tank capacity is often limited by design or weight considerations. The standard built-in tank holds 1.2-1.5 liters of mixture, which is not long enough when operating at full gas. Fuel consumption Two-stroke motors with a capacity of 5-10 hp. averages from 0.3 to 0.8 liters per hour, depending on the load.
Four-stroke engines are about 20-30% more economical, but their weight negates the advantage in range when considering the total weight of the equipment. For long-distance boat crossings, 320 cm is more rational to take an additional external fuel tank than rely on an integrated tank.
It is important to remember the quality of the fuel: the use of old gasoline or the wrong proportion of oil leads to the formation of soot on candles and the piston group. Fresh fuel mixture is a guarantee that you will not get stuck in the middle of the reservoir due to a clogged carburetor.
⚠️ Warning: Never store a full-tank engine indoors or off-season without canning. Residues of fuel can oxidize, forming resins that are almost impossible to remove without completely disassembling the carburetor.
Budgetary solutions and popular models
The market offers many options, from premium brands like Tohatsu and Yamaha For a 320 cm boat, it makes no sense to overpay for the over-life of powerful engines, since the loads are lower here. Budget two-stroke models with a capacity of 3.5-5 hp are often the best choice.
Forced water-cooled models are popular, quieter and more reliable than air-powered ones. When choosing, consider the availability of service and parts in your area. An engine without repair can become useless cargo.
Consider buying a used motor from a well-known manufacturer. The resource of high-quality low-power units is large, and with proper inspection you can buy reliable equipment for half the price.
Frequently Asked Questions (FAQ)
Can I put a 9.9 hp engine on a 320 cm boat?
Technically, it's possible if the transom can withstand this power. However, for a length of 320 cm, this is often redundant: the boat can become unstable on planing, and high-speed control will become dangerous. The optimal limit for this length is 6-8 hp.
Which screw is better for fishing from a 320 cm boat?
For fishing, where it is not the maximum speed, but the confident entry into mode and the ability to troll, it is better to choose a low pitch screw (Low Thrust) or a standard aluminum one. This will provide better traction when there is a cargo.
Do I need to register the motor for a boat 320 cm in GIMS?
Small vessels with an engine of more than 8 kW (approximately 10.88 hp) are subject to registration. Motors with a capacity of up to 10 hp inclusive registration in GIMS are not subject to registration if the total mass of the equipped vessel with an engine does not exceed 200 kg (which is almost always the case for PVC 320).
Why does the engine stop at idle speed?
The most common causes: a polluted carburetor, improper adjustment of the screw quality of the mixture, air sucking through gaskets or the use of poor-quality fuel, and the problem may be in the spark plug.