Choosing a 5 horsepower outboard motor is always a compromise between dynamics, fuel consumption and, crucially, the weight of the unit. The weight of the outboard motor is 5 hp Owners of small boats have to consider not only the data-sheet specifications of the engine, but also its physical mass, which will have to be constantly carried, loaded into the car and installed on the transom.
Many beginners mistakenly assume that the difference of 2-3 kilograms between different models is insignificant. However, in practice, this spread is felt very acutely, especially if you are transporting equipment alone or using the engine on a lightweight inflatable boat with a hard bottom. Understanding what the total weight is made of and how it relates to the type of engine will allow you to avoid mistakes when buying.
In this article, we will discuss in detail why two-stroke models are traditionally lighter than four-stroke models, how the presence of an electric starter and generator affects the final figures, and also consider specific examples of popular brands. outboard motor weight This is not just a dry number in the catalog, it is a parameter that directly affects the differentiation of the boat, fuel consumption and your comfort in operation.
Factors determining engine mass
The main weight of any outboard motor is given by its power plant and cooling system. In internal combustion engines, the main heavy elements are the cylinder block, crankcase, crankshaft and exhaust system. The structural differences between two-stroke (2T) and four-stroke (4T) units dictate the difference in their dimensions and weight. Two-stroke units are usually lighter, since they have a simpler design without a complex gas distribution mechanism.
In addition, the final weight is significantly influenced by additional components: the presence of an electric starter, a generator to charge the battery and a full-fledged pressure lubrication system (characteristic of 4T) adds to the weight of 3 to 7 kilograms. Also worth considering the weight of the lower unit - the bottom of the motor, where the gears of the gear gear gear gear and propeller. The more powerful the gearbox, the more massive it is, even if the engine power is formally the same.
Why is lower unit so heavy?
lower unit is made of high-strength aluminum alloys and contains a gearbox inside that has gears running in an oil bath, and its weight is necessary to balance the motor on the transom and ensure that the screw is properly immersed.
Materials used in manufacturing also play a role: Modern manufacturers are increasingly adopting composite materials for casings (engine covers), which allows you to reduce weight without losing strength. However, the main metal assemblies remain steel or aluminum, because they are subjected to enormous loads. The average weight of a two-stroke 5 hp engine is 19-22 kg, while the four-stroke analog weighs 25-28 kg.
Comparison of two-stroke and four-stroke engines
The main advantage of two-stroke engines with a capacity of 5 hp is their exceptional lightness. The lack of oil crankcase, valves and a complex lubrication system makes them an ideal choice for fishing enthusiasts who often have to drag equipment across the shore. boat-weight This is the key criterion in favor of 2T.
Four-stroke engines, despite their high mass, offer a number of undeniable benefits: quietness, efficiency and environmental friendliness, but these benefits come with extra kilograms, and the difference in weight can be as high as 30-40%, which is noticeable when loading a car trunk or mounting a small inflatable boat on a transom, where every gram is important for stability.
When choosing between these two types of engines, it is important to consider operating conditions. If you plan to use a boat for short fishing trips with one person, where mobility is important, the two-stroke will be out of competition. If the boat is used by the family, the motor is on the transom all the time or transported by a trailer, then the additional weight of the four-stroke will not be a critical problem.
Overview of the weight of popular models 5 hp
The outboard motor market is packed with offerings from various manufacturers, and the mass variance even in the 5 hp class can be significant. Tohatsu and YamahaThey've been honing their two-stroke engines for decades. HDX or ParsunThey often copy time-tested designs, so their weight specifications are usually close to the originals, but may differ due to the use of different alloys.
For clarity, a comparative table of the mass of the most popular models on the market is relevant for standard versions with a manual starter and without an integrated generator (where applicable for basic versions).
| Brand and Model | Type of engine | Weight (kg) | Features |
|---|---|---|---|
| Tohatsu M5BDS | 2 Tact | 19.0 | One of the easiest in the class. |
| Yamaha 5CMHS | 2 Tact | 20.0 | Classical reliable construction |
| Honda BF5D | 4 Crack. | 25.2 | Availability of a generator (optional) |
| Suzuki DF5AS | 4 Crack. | 25.0 | Digital ignition system |
| Parsun F5BMS | 2 Tact | 19.5 | Budgetary analogue of Tohatsu |
As you can see from the table, the two-stroke Tohatsu and Parsun models are doing great weight. The four-stroke Honda and Suzuki engines are heavier, but their weight is distributed differently, which can have a positive effect on the balancing of the boat. When buying, you should consider not only dry weight, but also the weight with a full tank, which will add another 3-4 kilograms to the total weight you have to drag.
The influence of weight on the driving performance of the boat
The excess weight of the motor on the transom can significantly change the boat's trim. If the stern is too submerged because of the heavy engine, the boat will start to go worse on planing, water resistance will increase and, as a result, fuel consumption will increase. For inflatable boats up to 3 meters in length, the weight of the engine 5 hp is the limit, and here every extra kilogram is noticeable.
On the other hand, too light a motor on a heavy boat can lead to insufficient swelling of the lower unit, which causes cavitation and loss of traction. boat-weight It should be related to the load capacity and design of the craft. For light PVC boats with low pressure inflatable floor (LBBB), lightweight two-stroke boats that are less stern are preferred.
When you set the motor on a transom, adjust the angle of inclination so that lower unit goes into the water at an optimal angle, which will help compensate for the difference in weight and improve the yield on planing.
Also worth noting is the effect of weight on handling: a heavy motor shifts the center of gravity backwards, which can make the boat more sensitive to wave when driving on the course. A light motor, in turn, makes the boat more "rotor", but with strong side winds, light stern can sail more strongly if the total weight of the boat is small.
Transportation and ease of use
Transportation is especially important for those who don't have a boat trailer, and loading the motor into the trunk of a car, lifting it up to the roof, or carrying it to the water, all of these things depend on how many kilograms you hold, and the difference between 19 and 27 kilograms is enormous if you have to carry the engine 500 meters on sand or rocks.
To make transportation easier, many manufacturers have provided special handles for carrying, but even with a comfortable handle, a weight of 25+ kg (4T) is a serious test for one person, especially when you consider that the engine still needs to be attached to the tank and the hummulus, in which case two-stroke models win unconditionally.
☑️ Criteria for choosing a motor for single fishing
If you're planning to fish alone, we strongly advise you to prioritize the weight of the engine, and the ability to quickly remove the engine, get it into the car and drive home without requiring help is often more important than saving 100 grams of fuel per hour, which is given by four-strokes. Mobility in fishing is the key to success.
Tips for Choosing Other Types of Boats
When choosing a 5 hp engine, you need to start from the type of your boat. For PVC inflatable boats with a length of 2.7-3.2 meters with a keel, the best choice will be light two-stroke models weighing up to 20 kg. They will ensure good dynamics and do not overload the transom. For aluminum boats ("Kandak", "Crimea") weighing more than 100 kg, you can safely take a four-stroke engine, since its weight will be less noticeable against the background of the weight of the hull.
⚠️ Warning: Always check the maximum power and load capacity of your boat's transom. Installing an engine that is too heavy on a light boat can cause a breakdown in stability and even tipping the vessel over in sudden maneuvers.
Also consider transom material. In inflatable boats, the transom is often made of plywood, sheathed with PVC. Prolonged pressure of a heavy motor can deform the transom or damage the cylinders at the mounting site. Using pendant boards or special mounts can partially solve the problem, but it is better not to exceed the recommended limits by the manufacturer of the boat on the weight of attachments.
For PVC boats up to 3.2 meters in length, the minimum engine weight (class 2T) should be a priority, for metal boats - reliability and efficiency (class 4T).
Frequently Asked Questions (FAQ)
Can I increase the power of the 5 hp engine to 6 or 8 hp?
Technically, many 5-6 hp engines have the same cylinder block, and the increase in power is possible by replacing the limiter in the carburetor or flashing the ECU. However, this removes the engine from the warranty and can lead to overheating or breakage, since the parts are designed for certain loads.
How much heavier is the motor with an electric starter?
The presence of an electric starter, battery and generator adds to the weight of a standard motor about 4-6 kilograms. For 5 hp motors, an electric starter is rare and is usually an option for 4T models.
Does the length of the lower unit affect weight?
Yes, long-dadewood (L - 508 mm) motors are heavier than short-dadewood (S - 381 mm) engines by about 1.5-2.5 kg due to the elongated lower unit pipe and intermediate body.
Which engine is lighter: a new Chinese or a used Japanese?
The new Chinese engine may be lighter due to the use of thinner metal and simple alloys, but this often affects the resource: B/w Japanese (Tohatsu, Yamaha) will have a declared factory weight that is time-tested, but can be heavier due to higher quality, but dense materials.