For any hydraulic motor considering purchase or already owning an aluminum boat, the parameter displacement It's the weight of the hull that determines how much power the engine will need to achieve the desired planing speed, and how easy it will be to unload the boat ashore. Ob They have earned a reputation for being unbeatable classics, but their weight is often the subject of heated debates on forums and at the berths.
Knowing how much your body really weighs Obcritical to the calculation load capacityIf you plan long-distance fishing trips with lots of gear, each kilogram of body weight takes away the payload. In this article, we'll take a closer look at the weight specifications of different modifications, from the classic Obi-M to more modern versions, and find out how weight affects handling.
It is worth noting that the stated factory figures are often different from what is shown. floor-loop It's influenced by the thickness of the metal, the number of welds and the equipment, and we'll look at all the nuances so you can make an informed decision about buying or upgrading your boat.
Technical specifications and weight of the body Ob-1
Classical ObThe archetype, often referred to as Ob-1, has become a benchmark for Soviet and post-Soviet small shipbuilding, with a total hull mass of roughly the size of the model. 250 kgIt's a pretty impressive figure that dictates its operating conditions, and that weight means that it's almost impossible to unload a boat on a trailer or a slipway alone without using a winch or a beam crane.
However, a large number of people have their own advantagesThe heavy hull is better at keeping the wave at full speed, less prone to yaw in lateral winds. The D16AT aluminum alloy that makes the boat is very durable, but adds weight compared to more modern but thin alloys. For many anglers, this "heaviness" is the guarantee of safety in a storm.
⚠️ Warning: When transporting on a passenger trailer, remember that the weight of the boat 250 kg plus the weight of the engine and equipment may exceed the permissible load on the breather and axle of the trailer.
The dimensions of the hull also play a role. 5 meters long and almost 2 meters wide creates a significant area of sailing and contact with water. So you can't just focus on the minimum values when you're choosing a motor. gelling with full load, you will need an engine with a capacity of at least 15-18 hp, and better - all 20-25 hp.
Why is Ob-1 so heavy?
The weight is due to the use of a thick sheet of aluminum (2 mm) and a massive transcrete, which is designed to fit heavy two-stroke engines of the last century.
Evolution of the series: the weight of models Ob-M and Ob-3
The upgraded version is known as Ob-MIt was an attempt by engineers to reduce weight and improve driving performance. 200-210 kgThe difference of 40-50 kg seems small on paper, but on water it feels like a significant improvement in acceleration dynamics, and the reduction in weight has allowed for less powerful, and therefore more economical, engines.
The easiest in the family is considered Ob-3She weighs about half as much. 180-190 kgThis achievement was made by optimizing the design of the set and using more rational cutting of sheet material, for summer residents and fishermen who often have to unload the boat by hand. Ob-3 It is the most preferred option among metal boats of this size.
- 🚤 Ob-1.Classic heavy body, maximum strength, ideal for large bodies of water.
- ⚓ Ob-MThe middle ground, the balance between weight and resilience, is popular with hunters.
- 🏎️ Ob-3Lightweight version for fast delivery to water, the best speed indicators.
It is important to note that the weight is indicated for the "head" body. consoleDecks, knobs and cans can add another 30-40 kg to the total weight. If you buy a used boat, be sure to weigh it with all the installed additions, as the previous owner could significantly weight the structure.
When you choose between models, remember: Ob-3 is lighter, but Ob-1 is more stable on the wavelength. Easy for transportation, and mass is for comfort.
Comparative table of model specifications
To illustrate the differences between the modifications, we turn to the numbers below, which shows how weight varies by model and year of manufacture. Please note that the data may vary by manufacturer, as production licenses vary. Obi. They were given to different factories.
| Model | Body weight (kg) | Load capacity (kg) | Recommended power (hp) |
|---|---|---|---|
| Ob (Classic) | 250 | 400 | 15-25 |
| Ob-M | 210 | 400 | 15-20 |
| Ob-3 | 190 | 350 | 10-15 |
| Ob-2 (project) | 230 | 380 | 15-20 |
Analyzing the table, you can see a direct relationship: reducing the weight of the body allows you to either increase the payload or reduce the requirements for engine power. loading capacity The Ob-3 is a little lowered by the engineers, which is a price for lightness, and it's an important nuance for those who take on 3-4 people and a full set of equipment.
Also worth noting is the difference in mass distribution: older models can shift the center of gravity, which requires the correct weight distribution. ballastIn the new modifications, this parameter is better taken into account, which makes the boat more obedient on the steering wheel.
Effect of weight on driving performance and fuel consumption
The weight of the boat directly affects it. hydrodynamicsIt's heavy. Ob It's going to be a long transitional phase, and it's going to be a long transitional phase, and it's going to be a high fuel consumption, because the engine is running at high speeds, and the boat is still pulling water on board, not sliding over it. Ob-3 "Highs up" on plane much faster.
But at full speed, the difference is smoothed out. The heavy boat, when it's gaining speed, is going more gently, smoothing out the impacts on the oncoming wave. ripple It can jump on excitement if you don't adjust the differentiation, so weight is always a trade-off between dynamic and comfort.
Fuel consumption is another critical parameter, and a 50 kg difference in weight can produce up to 15-20% fuel savings over long distances, if the engine is optimally selected. two-strokeHowever, which are not economical in themselves, reducing the weight of the hull is a real way to increase the range of navigation without refueling.
Problems of transportation and unloading on shore
Transporting a 200-kilogram boat is a separate task. boat-trailer When choosing a trailer, make sure that its total mass (including boat, engine and equipment) does not exceed the permissible for your car. Often owners forget that the weight of the trailer breathed is also distributed to the axle of the car.
When unloaded on unequipped shore, weight becomes the main enemy. Aluminum is slippery, and on wet grass or sand, move it. Ob It's very difficult to get out of here. roller-pillar Manual unloading is only possible with Ob-3 and then with a good slipway and the help of a partner.
☑️ Preparation for launch
There's a common mistake: trying to unload the boat backwards onto a steep slope. Obi. It's fraught with transom damage or rollover. Always try to pick out gentle areas or use special ones. triggerRemember, the inertia of 250 kg on wheels is a serious force that is difficult to stop.
Comparison with competitors and analogues
There are other aluminum boats on the market, for example. Crimea or Kazanka. Crimea It weighs about 230 kg, making it a direct competitor. Ob-MBut it's already less spacious. Kazanka-M It is lighter (about 150 kg), but much narrower and less seaworthy. The Ob remains the leader in terms of the combination of width, height and acceptable weight in its class.
Compared to modern boats, magnesium-aluminum alloys, then classical Ob It loses weight (modern analogues can weigh 140-160 kg at the same dimensions), but it wins in the price and availability of spare parts. Repair of the classic Ob is cheaper and easier, since the metal is cooked with conventional argon welding without much difficulty.
For those looking for an alternative, inflatable balloon boats are easier to find, but they are prone to puncture. Ob It's a tank on the water, and the choice is always up to the user: lightness and vulnerability, or weight and weight. sluggishness.
⚠️ Warning: Do not attempt to reduce the weight of the boat by cutting the brangouts or reducing the thickness of the metal, which will violate the tightness and strength of the hull, which can lead to a disaster on the water.
FAQ: Frequently Asked Questions About Boat Weight
How much does the real weight of the OB boat differ from the factory one?
The actual weight can vary by 10-15 kg in the higher direction due to the use of thicker metal in individual manufacturing plants, the presence of a layer of paint, dirt in the hold and installed equipment (anchor, chain), which is often considered as part of the weight.
Can you reduce the weight of the Ob to install on the roof of the car?
Theoretically, you can take the boat apart (if the design allows, for example, removable cans and console), but the body is monolithic. Installation of 200+ kg on the roof of the passenger car is dangerous and often prohibited traffic rules. For the Ob, only a trailer is needed.
What is the minimum motor required for an Ob weighing 250 kg?
To enter the planing with one person (80 kg) and a minimum fuel reserve (20 kg), you will need a motor with a capacity of at least 9.9 hp (actually 15 forces). For comfortable operation with passengers, 15-18 hp is recommended.
Does the weight of a boat affect speed with the same engine?
A lighter Ob-3 with the same 15 hp engine will accelerate faster and show a higher top speed than the heavy Ob-1, due to less water resistance and less displacement.
Where can I find out the exact weight of my particular boat?
The exact weight is listed on the boat's book or technical data sheet (formular), which was issued when buying, and if there are no documents, the only way is to weigh on a car scale or change with an error.