Among the huge number of swimming equipment produced by the domestic industry in the Soviet and post-Soviet periods, aluminum-boat The Ob M is one of the most striking of its kind, designed as a versatile workhorse for anglers, hunters and outdoor enthusiasts, capable of withstanding harsh operating conditions, and the AMG5 hull design ensures durability and corrosion resistance, making the boat relevant even decades after production.
The main feature of this model is its round-sheathThe hull, which is a stark contrast to Ob-1's predecessor and many of its competitors, is a form that allows it to more confidently navigate the wave, providing a softer ride and reducing the impact load on the crew. It is the hull's technical specifications, combined with the ability to install an outboard motor up to 30 hp, that have made this project so popular in Siberia and the Far East, where water bodies are often unpredictable and demanding for reliability.
Owners value the vehicle for its ease of maintenance and maintainability, because with proper care, an aluminum hull can last for decades. However, to fully unlock the potential of a vessel, you need to understand its dimensions, weight parameters and engine power limitations. In this review, we will take a detailed look at all aspects of the design so that you can make an informed decision about the purchase or modernization of this legendary vessel.
Shell design and materials
The basis of the reliability of the boat "Ob M" is its hull, made by welding from sheet Aluminum-magnesium alloy AMG5This material is not chosen by chance: it has excellent weldability, high corrosion resistance in fresh and sea water, and sufficient strength. The bottom is 2 mm thick, which provides protection against impacts on small stones or a heater, and the sides and deck are made of a sheet thickness of 1.5 mm to reduce the total mass.
The shape of the body is of the type monodrone With a rounded nose, which is an evolutionary step forward from the sharp-nosed modifications. The hull cheekbones are raised high in the nose, which improves germination on the wave and prevents splashing. In the aft, the bottom has a slight keeliness, which provides course stability when driving, especially at high speeds or in lateral winds.
Features of welds
Welds are welded with argono-arc welding, which ensures high tightness and strength of the joint. However, over time, microcracks may appear in stress areas (especially at the transom and zygomatic bends) that require attention during annual inspection.
It is important to note that despite the strength of the alloy, aluminum structures are sensitive to electrochemical corrosion when in contact with other metals. stainless-steel Or specialized alloys, avoiding direct contact with copper or brass without insulation, and tightness is ensured not only by welding, but also by properly installing removable elements such as haunducts and jars.
⚠️ Note: When buying a used boat, the Ob M first check the transom and zygomatic bends for cracks. Aluminum is prone to fatigue fracture, and the presence of microcracks in these areas requires immediate brewing.
Overall dimensions and weight parameters
For transportation on a trailer or roof of a car, accurate data on the dimensions of the vessel are critical. The Ob M boat has a length of 4200 mm, which makes it a medium motorcycle class. The width on the midsection is 1500 mm, which ensures sufficient stability in the parking lot and allows a crew of 3-4 people to comfortably accommodate. The height of the board is considered optimal for spray protection, but requires accuracy during landing, so as not to disturb the centering.
The dry weight of the hull without attachments and motor is about 150 kg. This paramette is one of the key when choosing a traction car for transportation. While 150 kg is not a record low for a four-meter boat, it is an acceptable weight for launching two people from a flat shore or using a light trailer. The distribution of weight along the length of the hull contributes to a good germination even with moderate engine power.
The inner volume of the cockpit allows you to accommodate the necessary equipment for a multi-day hike. The height of the cockpit from flooring to coaming allows you to install full seats with backs or even equip a small runduk sofa in the nose. geometrical They become the defining factor in comfort.
Keep in mind that the actual weight on the water is always higher than the passport weight because of the water that gets into the hold, oil, fuel and personal equipment. So when calculating the carrying capacity of the trailer and the car, always add a margin of 20-30% to the base weight of the body.
Passenger capacity and passenger capacity
The Ob M's official carrying capacity is 400 kg, which includes the weight of crew, engine, fuel, oil, anchor, equipment and any other cargo on board, and exceeding this limit is dangerous: the boat loses its buoyancy, increases draught, and the boat becomes sluggish in management, and increases the risk of water pouring through the side in choppy conditions.
Passenger capacity is limited to four people, and this is not only a limit on payload capacity, but also on having enough seats and weight distribution to keep the right differentiation, and if you plan to bring trophy fish or heavy camping gear, you'll have to reduce the number of passengers to two or three.
- 🚣 Maximum load capacity: 400 kg (including engine and crew weight).
- 👥 Passenger capacity: up to 4 people (by number of seats).
- ⚖️ Recommended load for planing: no more than 300 kg (for engines 15-20 hp).
Experienced water-engineers know that the Ob M is best when loading about 250-300 kg. In this mode it confidently goes to the plane, easy to control and saves fuel. An overloaded boat with difficulty breaks off from the water, lies on the "belly" and creates a dangerous situation, especially if suddenly you need to maneuver sharply.
⚠️ Warning: Never spread the load on one side only or only in the bow/stern. Shifting the center of gravity can lead to roll, which the sailing of the hull will increase the wind, which can lead to tipping.
Motorization and speed specifications
The OBM trunk plate is designed to install outboard motors up to 30 hp (22 kW). However, the most optimal and popular solution is the use of engines in the range of 15-20 hp Two-stroke or four-stroke "Japanese" and their Chinese counterparts of such power can reach speeds up to 35-40 km / h with a crew of two and a minimum load.
With a 25-30 hp engine, the speed can rise to 45-50 km/h, but operating such a light and wide boat at high speeds requires experience. At full gas, the Ob M can start to prowl or dangerously tilt in corners due to flat sterns. In addition, constant operation at the power limit quickly wears out the transom.
To save fuel and increase the engine life on the boat "Ob M" optimally use the propeller with a pitch matched to the average load (2 people + tackle).
Speed rates are directly dependent on the condition of the bottom; watering with algae or dents can reduce the maximum speed by 10-15%; regular washing and polishing of the bottom (if the boat is stored on water) help maintain high driving performance.
Below is a table of approximate speed specifications depending on the power of the engine and load (the data averaged depend on the screw and the state of the engine):
| Engine power (hp) | Loading (kg) | Max. speed (km/h) | Mode of traffic |
|---|---|---|---|
| 9.9 hp | 150 kg | 22-25 | Water Displacement / Beginning of Gleaming |
| 15 hp | 200 kg | 32-35 | Confident glossing |
| 20 hp | 250 kg | 38-42 | Optimal cruiser |
| 30 hp | 300 kg | 45-50 | Forced (requires experience) |
Setup and capabilities of tuning
The basic equipment of the Ob M is traditionally Spartan: the hull, two removable cans (seats), the keys for oars and the lock for the mounting of the tiller. Oars are usually not included in the kit, they must be purchased separately. customization and to be fitted to the specific needs of the owner.
The most popular type of tuning is windscreen, and because there is no standard glass, owners often order plexiglass to their own sizes or use off-the-shelf solutions from other boats to adapt the mounts, which greatly improves comfort when driving against the wind and in the rain.
- 🛡️ Installation of windscreen (plexiglass 5-8 mm).
- 🪑 Replacement of wooden cans with soft seats with runduks.
- ⚓ Equipment noselocker (anchor runduk) for storage of tackles.
- 💡 Installation of running lights and navigation electronics (echo sounder, GPS).
Also common is the installation of a tent-transformer, which turns an open boat into a mini cabin, allowing you to spend the night on the water or hide from mosquitoes. Many owners change the regular keys for more reliable turning mechanisms, and on the bottom they put plywood or composite decking for thermal insulation and ease of movement.
☑️ Season preparation checklist
Advantages and disadvantages of the model
Over the decades of operation, the Ob M has proven to be a reliable but not without flaws, and its unquestionable advantages include its indestructibility. Aluminum does not rot, does not fear impacts on ice or rocks like fiberglass, and is easily repaired in the field. Its simplicity means that there is nothing to break down there, except for the motor itself.
But there are downsides, and the main one is noise. The aluminum hull acts as a resonator, amplifying the sound of the motor and the waves. Without the additional noise insulation (which many people put on their own), talking full-time can be difficult. The second downside is the lack of buoyancy. If the boat flips over or gets a hole, it will sink with the crew, because there are no built-in buoyancy blocks in the basic version.
⚠️ Attention: Lack of built-in buoyancy is a critical risk factor, and when operating Ob M, the presence of life jackets on each crew member is a safety requirement, not a recommendation.
However, the combination of low price (especially in the secondary market), maintainability and capacity makes this boat a great choice for beginners and avid fishermen willing to put up with noise for reliability.
The Ob M is a choice for practicality and maintainability at the expense of comfort and quietness, ideal for fishing and hunting in remote areas.
Frequently Asked Questions (FAQ)
Is it possible to go to sea on the OBU M boat?
It is possible to go out to sea, but with restrictions. The boat is designed for protected water areas. In calm weather (waves up to 0.5-0.75 m), access to the coastal zone is possible, but high sides and low weight make it vulnerable to side wind and large waves. It is not intended for open seas.
Which motor is better to choose: 2T or 4T?
For the 150kg Ob M, the 4T is preferable for noise and fuel consumption, but it is heavier. The two-stroke (2T) is lighter and cheaper, which is important for passenger car transportation, but noisier and more voracious. For fishing, the 4T is often chosen for silence, for hunting and long distances - 2T for weight and range.
Do I need to register a boat with GIMS?
Yes, the Ob M is over 3 meters long and weighs less than 200 kg, but when installing an engine with a capacity of more than 8 kW (about 10.8 hp), registration is mandatory. If the engine is less than 10.8 hp, registration is not required, but it is advisable to have the rights and documents for the boat with you to avoid questions.
How to keep a boat in the winter?
An aluminum boat is best kept upside down under a canopy or in a garage so that there is no snow or water inside. If you store it outside, be sure to remove the engine, shut down all the holes and cover it with a tent, leaving ventilation gaps. Soil contact should be excluded - use stands.