The question of how much the Ob M weighs is one of the most critical for owners planning to buy or upgrade their boat. This legendary duraluminium Kazanka has been the benchmark of reliability and maintainability for decades, but its design is not a good choice. design Understanding the actual mass of the body is necessary not only to calculate the load capacity, but also to select the right trailer, assess the vehicle's patency when launching and select the optimal outboard motor.
Many potential buyers, relying on the dry numbers in old passports, often forget that the actual weight may differ significantly from the manufacturer's stated, this is due to the use of various aluminum alloys, the thickness of the rolled products in different years of production, and the availability of additional equipment, which over time grows on the boards. Ob M. It is not just a set of numbers in the specification, it is a complex engineering object, where each kilogram plays a role in stability and speed.
In this article, we will take a closer look at the weight of this model, from the weight of the naked body to the full gear with the engine and fuel, how the thickness of the metal affects durability and why a lightweight body is not always good, and we will also touch on the topic of load distribution, which is critical for safety on water, especially in the case of excitement.
Design features and weight of the body
The body of the Ob M is made of duraluminium alloy, which provides high strength at a relatively low weight compared to steel counterparts. However, dural requires careful treatment of corrosion, although less susceptible to it than conventional steels. bottomless The additional elements are about 115-120 kg, a base value that should be used in the calculations.
The most important element that adds significant weight is the flat removable bottom, which is made of 2 mm thick aluminum sheet and reinforced by longitudinal and transom profiles. The weight of the bottom itself varies between 35 and 40 kg. It is the presence of a removable bottom that makes this boat unique: if necessary, it can be operated as a low-draught flatbed, removing the weighted element, although this reduces the weight of the weight. seaworthiness and comfort.
Why is the bottom removable?
The removable bottom was introduced for ease of transportation and storage, as well as for the possibility of using a boat in shallow water, but when assembled, it significantly increases the rigidity of the structure and extinguishes the shocks against the wave.
The total weight of the case in the assembly (body plus bottom) is usually about 155-160 kg. It is worth noting that in older copies produced in the Soviet period, the metal could be thicker, which increased the total weight, but increased the safety margin. Modern repairs or replacement of sheets can also change the weight parameters if used metal of a different brand or thickness.
The total weight of the body Ob M in the assembly with the bottom is about 160 kg, which requires the mandatory use of a trailer for transportation.
Mass of transmutation board and attachments
The trayboard is another critically important piece that is often overlooked when weighing, made of wood (usually beech or oak) covered with waterproof plywood or varnish, and has a metallic edge, weighing about 10-12 kg. Despite its apparent ease, the element experiences tremendous stress from the surface of the tranny. outboard.
When calculating the total weight of a boat, you also need to consider the mass of permanent equipment, which is rarely removed, including knobs, cans (seats), switches and a liner device. The equipment can vary, but on average these elements add another 15-20 kg to the total weight. If you use a boat for fishing, the weight of the anchor, anchor chain and bolts should also be taken into account in the balancing.
The standard power of the recommended engine is up to 30 hp, although many put more powerful units. The weight of the engine itself (for example, Yamaha 30 or Tohatsu 30) is from 45 to 55 kg. Thus, only the hinged complex (trans + motor) adds more than 60 kg to the stern, which significantly affects the weight of the engine. differentiator boat.
- 🚤 A transom board made of hard wood weighs about 11 kg.
- ⚓ Anchor equipment and chains add a minimum of 8-10 kg.
- 🛠️ Removable cans and kunduks in the kit are about 15 kg.
Effect of Metal Thickness on Durability and Mass
The thickness of the aluminum sheet used directly determines how much the Ob M weighs in a particular instance. Factory standards suggested using sheets 2 mm thick for the bottom and 1.5-1.8 mm thick for the sides. However, in repairs, owners often use more affordable or thick metal, which leads to an increase in weight. Thickening the metal of the sides to 2.5 mm can add to the weight of the hull more than 30 kg.
On the one hand, thicker metal increases the survivability of the boat when hitting rocks or ice. On the other hand, being overweight reduces the payload capacity and requires a more powerful motor to go into sleeving. duraluminium D16T brand, which is most often used, has excellent strength, but with frequent welding loses its properties, so digesting a boat with a margin is not always advisable.
When buying a used boat, be sure to feel the seams and pay attention to the color of the metal. Darker, oxidized areas may indicate welded inserts that could change the weight and geometry of the hull.
If you plan to use a boat for long exits with lots of gear, it is better to keep the weight of the hull minimal, observing the factory parameters of the thickness of the metal. Excessive weighting can make the boat roll on the wave.
⚠️ Note: The use of steel inserts in the repair of the bottom is strictly prohibited due to the difference in electrochemical potentials, which will lead to instant corrosion of the aluminum case at the contact point.
Capacity and passenger capacity
The passenger capacity of the Ob M is 400 kg. This figure includes the weight of passengers, cargo, engine installed and fuel. Given that the boat itself weighs about 230-240 kg, it becomes clear that the payload reserve is small. When fully loaded (4 people for 80 kg + 20 kg of cargo), the boat goes to the limit of its capabilities.
Excessive load capacity leads to a decrease in the height of the board above the water, which increases the risk of flooding with the wave, especially critical for the Obi M, since it has rather scanty contours and a high side, but when overloaded becomes inert in control. Resilience The boat also suffers: the center of gravity shifts and the boat becomes more inclined to roll.
The weight distribution within the cockpit is as important as the overall weight. Passengers must sit symmetrically relative to the diametric plane. Shifting the load to one side can lead to a dangerous roll, especially when abrupt maneuvers or bends a sharp turn. Ob M. The importance of uniform loading for safety is always emphasized.
Weight comparison with other models of aluminum boats
To make an objective assessment of how much the Ob M weighs, it is useful to compare it with its competitors: the classic Kazanka (Project 460) weighs about 145 kg, making the Ob M about 15-20 kg heavier, a difference due to the more powerful hull set and the presence of a removable bottom at the Ob. However, the Kazanka-M already weighs about 160 kg, which puts these models in a row.
More modern aluminum boats, such as the Windroc or the Salute, can weigh between 130 and 170 kg depending on the modification. The M is in the middle of this range, offering a trade-off between strength and weight. In comparison, similarly sized PVC inflatable boats (3.6-4.0 m) weigh 3-4 times less, but do not have such a weight. wear-resistant and repairability in the field.
| Model boat | Body weight (kg) | Load capacity (kg) | Recommended power (hp) |
|---|---|---|---|
| Ob M. | 160 | 400 | 30 |
| Kazanka (460 projects) | 145 | 400 | 25 |
| Salute 370 | 135 | 350 | 25 |
| Crimea (M) | 195 | 500 | 40 |
Transportation and preparation for the season
Transporting a boat weighing more than 200 kg (assembled with an engine) requires a reliable trailer. Boat trailers must be designed to have a load of at least 350-400 kg to have a margin of safety. When towing, it is important to consider that the center of gravity of a loaded trailer must be above the wheel axis or slightly ahead of it for stability on the track.
Before the season begins, it is recommended to conduct an audit of all weight elements, check the condition of the transom, the mounting of the cans and the integrity of the bottom. If you plan a long expedition, make a list of equipment and weigh it in advance, this will help to avoid overload and ensure a comfortable and safe swim. Security The water starts with the correct calculation of loads.
☑️ Preparing the boat for the season
Remember, water creates additional resistance, and every extra kilogram requires more fuel to cover the distance. Weight optimization is not just a matter of performance, but also economic feasibility. Lighter boats, less fuel consumption, less engine wear and more driving pleasure.
How to weigh the boat OB M at home?
For accurate weighing, use a baggage weighting scale or a car scale. The boat must be weighed dry, without water in the hold. First, the body is weighed with the bottom, then the motor and equipment are weighed separately. The sum of these values will give an accurate weight. It is important to weigh on a flat solid surface.
Can you reduce the weight of the Obi M to improve driving performance?
Weight loss can be achieved by replacing a wooden transom with a cellular aggregated aluminum (significant savings), by eliminating heavy hazelnuts in favor of lightweight bags, and by using a light anchor. However, you can not remove the bottom or reduce the thickness of the metal of the case - this will violate strength and safety.
Does rust affect the weight of the boat?
Aluminum oxidizes to form an oxide film that protects the metal but does not add significant weight. However, the accumulation of dirt, silt, old paint and algae in hard-to-reach places (especially under linings and in corners) can add a few pounds to the total weight of the boat.
⚠️ Warning: When installing a more powerful motor than recommended, be sure to check the condition of the transaxboard. Increased weight and traction can lead to the collapse of the transom and loss of the motor.
In conclusion, the weight of the Ob M is a balanced parameter that has been in use for decades, knowing the exact weight of your specimen will allow you to correctly approach the issues of towing, storage and, most importantly, safety on the water. Don't neglect regular inspections and maintenance, and this reliable metal boat will last for many years.