Aluminum mottled Ob 3 Deservedly considered one of the most popular models for fishing and recreation on the water in Russia, this boat, manufactured by the Novosibirsk Metal Plant, is a deep modernization of the classic Obi, which has improved driving performance and comfort. dimensions.
Understanding the exact parameters of the body is necessary not only for the choice of trailer, but also for calculating stability and capacity. Unlike inflatable counterparts, the rigid housing dictates its storage and transportation requirements. In this article, we will discuss in detail all linear parameters, the effect of modifications on the overall length and specific operation of this boat.
Knowing the exact numbers will allow you to avoid unpleasant surprises when loading on a trailer or when passing under low bridges. Housing geometry The Ob 3 is designed to make the most of the interior space while maintaining the compactness acceptable for towing by a passenger car.
Basic dimensions of the body and their impact on operation
The basis for all calculations is length The size of the boat, which is 4,250 mm in the Ob 3, includes the entire structure from the forehead to the transom, but does not include hinged elements such as motor brackets or liner fencing, if they are installed additionally, and this figure of 4.25 meters is the determining figure when choosing the length of the trailer and the space in the garage.
Body width The mid-spangout is 1600 mm, which is quite wide for a boat of this class, which provides excellent stability in the parking lot and when fishing in stagnant water. However, the wide waist of the boat increases sailing speed in the side wind while driving on the highway on the trailer, which requires more careful driving of the tractor.
The height of the side on the midfield is 700 mm. Such a side in combination with high bow and aft bulkheads allows you to feel confident on the wave. Ob 3 has a glossing body with sharpened contours, which also affects the distribution of dimensions in height, especially in the nose, where the side rises higher for better seeding on the wave.
⚠️ Note: When calculating the height of the garage storage boat, keep in mind that the height of the side is 700 mm is the minimum. The actual height from the bottom to the top section of the side can vary depending on the keeliness and the installation of additional elements, such as: coamings Or leer racks.
For accurate space planning, it is useful to know that full-body The boats in the basic configuration is about 230 kg. This means that the dimensions of 4.25 by 1.6 meters carry a serious weight that can not be ignored when launching without the use of a ladder or a powerful crane-beam.
Detailed analysis of length: from the forehead to the transom
A 4,250 mm long boat is a trade-off between seaworthiness and transportability, and a boat of this length can already hold a wave height of up to 0.6 meters, which is not available for shorter versions like Kazanka-M or Obi-1. However, this size is often the limit for owners of small cars when towing.
It is worth noting that lower unit For Ob 3, optimal engines with a 400-500 mm lower unit (standard S or L), which adds another 20-30 cm to the total length when transporting if the motor is not removed, is critically important to consider when parking a trailer in narrow garage cooperatives.
Inside the cockpit, the useful length is much smaller than the overall length due to the presence of transom and bow bulkheads, the distance between the bulkheads determines the number of transom cans installed and the possibility of placing an inflatable mattress for the night. Ob 3 It is designed so that two adults can comfortably sleep across the hull, which is an outstanding indicator of ergonomics for a boat of 4.25 meters in length.
When buying a trailer, it is recommended to take a model with a margin of length. If the dimensions of the boat Ob 3 are 4.25 m, then the trailer should be designed for a minimum of 4.5-5 meters to ensure the correct alignment and reliable attachment of the nose and stern rollers.
Width and interior space of the cockpit
The 1,600mm width is the middle ground for aluminum boats of this class, which can accommodate three fishermen comfortably without disturbing the centering, and the narrower boats (1,300-1,400mm) can no longer allow two adults to move in the cockpit, making it difficult to change seats or catch large fish.
The inner width of the bottom is smaller than the outer width due to the zygomatic curves and the presence of a timber. transom-can The Ob 3 is made as wide as possible. Standard removable jars are about 1450-1500 mm long, which allows you to sit with your legs wide apart, or use them as a tool table.
- 📏 Overall width of the flat beam: 1600 mm
- 📐 Bottom width (internal): about 1100-1200 mm
- 🚣 Useful width of the cockpit: about 1350 mm
- ⚖️ The width of the transom plate: corresponds to the width of the bottom in the stern
Particular attention should be paid to the width of the transom. Motor niche The Ob 3 has standard dimensions to allow an engine to be installed up to 30-40 hp (although the passport often limits it to 25 hp for safety) and the width of the engine niche allows one powerful motor or two low-power electric motors/gasoline engines to be mounted on a twin-engine bracket.
⚠️ WARNING: When installing two motors or a powerful bracket, make sure the overall width of the structure in the stern does not exceed the size of the boat, otherwise this may disrupt the balancing and create water resistance.
Height, keeliness and seaworthiness
The 700 mm height of the cockpit ensures dryness even when moving against a wave, which is especially important for fishing when you need to be in a boat, and the high side also acts as a protection against spray, which inevitably fly when planing at speeds above 30 km / h.
Kieliness The bottom of the transom is 10 degrees, and this is directly related to the vertical dimensions of the body. The wicker bottom requires a higher stern height to maintain volume and buoyancy. The Ob 3 has a moderate keeliness, which allows it to plane confidently even with low-power engines, but still remain quite soft on the go.
By comparison, the bow can reach 900 mm or more, which is typical for boats with high seaworthiness, and this geometry prevents the boat from flooding with the oncoming wave. Ob 3 They are often used in large reservoirs and coastal areas where board height is a critical safety parameter.
Influence of the height of the boat on sailing
High side (700 mm and above) significantly increases the sailing speed of the boat when towed on the highway. In windy weather, the fuel consumption of the tractor car can increase by 15-20% due to aerodynamic drag.
Comparison of modification sizes: Ob 3, Ob 3M and versions
The Ob range has evolved over time, and the sizes of the different boats may vary slightly. The classic Ob 3 has become the benchmark, but there are M-indexed versions (renovated) and other variations. The main difference is often in the reinforcement of the structure and the slight change in the thickness of the metal, which has little effect on the outer dimensions, but changes the weight.
Below is a table comparing the main overall parameters of the classic Ob 3 and related models to understand the evolution of dimensions:
| Parameter | Ob 3 (Classic) | Ob 3M | Ob 1 (for comparison) |
|---|---|---|---|
| Length overall, mm | 4250 | 4250 | 3900 |
| It's overall width, mm. | 1600 | 1600 | 1500 |
| Height of the side, mm | 700 | 700 | 600 |
| Body weight, kg | 230 | 250 | 160 |
| Load capacity, kg | 500 | 500 | 400 |
As you can see from the table, dimensions The increase in mass in the 3M version is due to the use of a thicker aluminum-magnesium alloy AMg5M, which has a positive effect on strength, but requires a more powerful motor to get on plane with full load.
Transportability and trailer requirements
Given the length of 4.25 m and width of 1.6 m, the boat is classified as large for passenger towage. Standard European boat trailer often has a gauge and platform width of 1.5-1.6 m, so the Ob 3 fits into them with minimal gaps. This requires accurate alignment during loading, so as not to damage the sides of the trailer elements.
For carriage Ob 3 It is recommended to use trailers with a gross weight of up to 750 kg (category B is right), since the total weight of the boat, engine (up to 80 kg) and equipment easily exceeds 350 kg. The trailer's breath It should be long enough to ensure the correct angle of attack when launching, given the solid length of the hull.
- 🚗 Required category of rights: B (with a trailer weighing up to 750 kg)
- ⛽ Fuel consumption during towing: +2-3 l / 100 km to base flow rate
- 🅿️ Storage area dimensions: minimum 4.5 x 2.0 m
When driving on the highway with such a boat on the roof (which is almost impossible for Ob 3 due to weight and length, only on the trailer) or on the trailer, you must observe the speed mode. The length of 4.25 meters creates significant inertia, and the maneuvers of the rearrangement should be smooth.
☑️ Check before the boat trip
Capacity and passenger capacity in size
The passenger capacity of the Ob 3 is 5 people, and this limitation is dictated not only by the deck area, but also by the buoyancy reserve. With dimensions of 4.25 x 1.6 m, you can theoretically accommodate five adults, but the boat feels most comfortable with 2-3 anglers and a full set of equipment.
Load capacity 500 kg allows you to take on board a significant amount of equipment: sonar, anchors, tents, fuel and food reserves. The volume of the cockpit allows you to move freely, which is important when actively fishing with spinning or trolling, where you need constant work with rods on different sides.
⚠️ Note: Do not exceed the maximum carrying capacity specified in the data sheet. Overloaded boat lands on water below the design waterline, which reduces the height of the free board and makes the vessel dangerous for operation even in calm water.
For overnight stays in the boat, the dimensions allow you to install an inflatable mattress measuring approximately 180 x 120 cm in the central part of the cockpit, occupying almost the entire useful width between the sides. This makes Ob 3 an excellent option for multi-day autonomous hikes.
To increase the usable area during the night, use special inflatable sleighs or cocoons that repeat the contours of the boat, allowing you to effectively use the space near the sides, where banks are usually located.
FAQ: Frequently Asked Questions About Size
Will the Ob 3 fit into a standard garage?
A standard garage measures approximately 3x6 meters or 4x6 meters. In length (4.25 m) the boat will fit into a 6-meter garage with a margin, but in width (1.6 m) it may require careful parking, especially if the garage stores tools or racks. Be sure to measure the width of the gate, it must be at least 2.2-2.5 meters for a comfortable arrival with a trailer.
Can I carry Ob 3 on the roof of a car?
Theoretically, you can have a large trunk and a long body (wagon or pickup truck), but the weight of the boat (230 kg) exceeds the permissible load on the roof of most cars (usually 75-100 kg). The only safe way to transport is to use a specialized boat trailer..
What is the minimum length of the trailer for Ob 3?
The length of the trailer support surface must be at least 3.5-3.8 meters to ensure reliable fixation of the hull at two points (nose and in the cockpit area). The total length of the trough and the frame will be larger than the dimensions of the boat, making about 5-5.5 meters.
Does the size affect registration in GIMS?
The dimensions directly affect the classification: Ob 3 is less than 5 meters long and less than 200 kg in running order without motor and equipment, only the hull, but with motor and equipment, the mass often exceeds 200 kg. However, according to current regulations, small craft weighing up to 200 kg and engine power up to 8 kW (10.88 hp) do not require registration. Ob 3 are usually recorded, since in the sum with the engine and equipment it goes beyond the exemption.
The dimensions of Ob 3 (4.25×1.6 m) are optimal for family holidays, providing a balance between internal capacity and the possibility of transportation by a standard passenger trailer.