A properly designed or self-made outboard motor stand is not just a storage convenience, but a critical element of the safety and durability of your equipment. Many water appliance owners underestimate the importance of fixing a lower unit upright, which often leads to deformation of the oil ducts, corrosion of exhaust pipes, and damage to the lower unit pipe when parking is incorrect. It is the exact size of the outboard that determines how reliably the unit will be fixed in the off-season or during transportation on the trailer.
In this article, we will discuss in detail all the nuances of designing a support structure, from the choice of materials to the final welding of the nodes. You will learn why standard factory dimensions may not be suitable for your particular case and how to calculate the dimensions of the base under the weight and dimensions of your body. cross-engineWe will not use abstract tips, but will provide specific numbers, tables and diagrams that will help create a reliable foothold.
Miscalculations of height or width of the support pad can cost you expensive repairs, for example, if the center of gravity is shifted too high, the structure can tip over with a gust of wind or careless touch. Therefore, before you pick up a Bulgarian and a welding machine, you need to clearly understand the physics of the process and the process of the construction. lower unit geometrySo let's look at what are the basic parameters for creating the perfect stand.
Criteria for the selection of support parameters
The first thing to start designing is to define the type of stand: they are stationary for garage storage and mobile for trailer transport. For stationary models, the stability of the base becomes the key parameter, while for mobile models, the dimensions and weight. Breadth of base It must be such that the motor does not fall to the side even with a strong side wind or surface tilt.
The second important criterion is the material. The most common type of piping is a square tube, because it has great resistance to twisting, but if you plan to keep the motor outdoors, the metal thickness must be increased to compensate for possible corrosion in the future. clearance The bottom of the motor above the ground so that the lower unit does not touch the ground.
β οΈ Warning: Never make the height of the support pad below the minimum gap specified in the engine data sheet, otherwise, when installing the unit, you risk damaging the anti-cavitation plate against the upper edge of the pipe.
The third aspect is the way the motor itself is attached to the stand, and some designs involve rigidly fixing the translucent with strubs, others relying on the lower unit pipe through rubber gaskets. seating-size And there are additional elements, like stops or clamps, and universal stands are often adjustable heights, which complicates the design, but makes it applicable to different models.
Standard dimensions and size tables
There are averaged values that are suitable for most popular models with a capacity of 2 to 15 horsepower. For such engines, a square area of 400Γ400 mm or a rectangular 500Γ350 mm is considered optimal. The height of the rack usually varies between 600-800 mm, which allows you to work comfortably with the engine without tilting too low.
More powerful engines (from 20 hp and above) require reinforced designs. Here the size of the outboard motor stand increases in proportion to the weight. The base can reach 600 x 600 mm, and the wall thickness of the profile pipe should be at least 3-4 mm. The table below shows the recommended parameters for different power classes.
| Motor class (hp) | Motor weight (kg) | Recommended base size (mm) | Stand height (mm) | Section (mm) |
|---|---|---|---|---|
| 2 - 5 hp. | 25 | 350 x 350 | 500 - 600 | 40 x 40 x 2 |
| 6 - 15 hp. | 25 - 45 | 400 x 400 | 600 - 700 | 50 x 50 x 2.5 |
| 20 to 40 hp. | 45 - 80 | 500 x 500 | 700 - 800 | 60 x 60 x 3 |
| 50+bhp. | 80 | 600 x 600 | 800 - 900 | 80 x 80 x 4 |
It is important to note that the dimensions can be adjusted depending on the length of the lower unit. Short-legged models (S) require a lower height of the rack compared to long-legged ones (L). If you plan to use one stand for different engines, it is better to focus on maximum dimensions and make a design with a margin of safety. Geometric accuracy It plays a smaller role than the stability.
When welding the base frame, use magnetic coalstones to expose right angles - this will prevent the structure from skewing, which is difficult to correct after the metal cools down.
Calculation of the height and angle of inclination of lower unit
One of the hardest things about building a stand is to make sure that the lower unit angle is right when it's stored. Although the motor has to stand upright to drain water, in some cases (for example, when you're in a trailer for a long time) you need to simulate the transom angle. The standard transom angle is about 10-15 degrees, but for the stand-up, we tend to go to the transom angle. verticality (0 degrees relative to the vertical).
The height of the support pad is calculated so that the screw does not touch the floor, but the whole structure is not too bulky. The formula is simple: take the length of the lower unit from the mount flange to the end of the screw, subtract 10-15 cm of margin and get the height of the rack. For two-stroke motors, it is critical to ensure that you can fit into the "tamplin" position to drain condensate, which also affects the position of the valve. top-piece.
If you're making a tilt stand to simulate a boat installation, the top pad should be beveled or sloping, but experts recommend that you use a strictly vertical position for long-term storage so that the oil is evenly distributed in the crankcase and does not leak out through the glands. Horizontal plane The top support is the safest solution for most users.
β οΈ Note: When calculating height, consider the height of the highest user β the upper edge of the lower unit should be available for maintenance without using a ladder.
Materials and tools for manufacturing
To create a reliable design, you will need high-quality metal. The optimal choice is a profile pipe made of structural steel Ε 3. It is well cooked, easy to work and inexpensive. For the upper area, where the motor comes into contact with metal, it is better to use a sheet 3-4 mm thick, reinforced with stiffness ribs, to avoid bending under weight. heavy-engine.
As a coating, it is recommended to use rust enamel or powder paint. Conventional nitro paint will quickly get peeled from vibration and contact with oil. You will also need rubber pads (you can use pieces of conveyor belt or car mats) that will prevent slipping and scratches on lower unit. Polyurethane wheels It will be a great addition to the mobile version.
The list of necessary tools includes:
- π οΈ Corner grinding machine (Bulgar) with metal discs.
- β‘ Welding inverter (for pipes up to 60 mm, 120-140 Amperes is sufficient).
- π Roulette, coal and marker for marking.
- π¨ Hammer and sweeping circle to remove slag.
βοΈ Preparation for welding
Step-by-step instructions for the assembly of the structure
The fabrication process starts with cutting the workpieces according to the sizes chosen. The bottom frame is assembled first. If you make a 400x400 mm square, you'll need 4 segments of the profile pipe. Weld them into a rectangle, checking the diagonals -- they should be perfectly equal, so you'll be stable and there's no distortion.
Then weld the vertical struts. For more rigidity, you can make not one central strut, but two on the sides, connecting them with lintels. The upper platform must have sides or stops to keep the engine from slipping. In the center of the site, you often weld a short pipe segment or pin that enters the drainage hole of the lower unit (if the engine design allows), or you put stops under the brakes. slab-stove.
The final step is to strip the seams and paint. Be sure to degrease the surface before applying the paint. After drying, install the rubber linings. If the stand is mobile, the wheels are attached to the bottom frame through swivel mechanisms, preferably with brakes.
The Secret to Sustainability
To increase the stability of the light support in the lower frame, you can insert lead loads or weld a pocket to install heavy pancakes from dumbbells, which will reduce the center of gravity.
High-quality cleaning of welding seams and anti-corrosion coating prolong the service life of the stand in conditions of high humidity several times.
Frequent errors in design and assembly
The most common mistake is saving on metal. A thin-walled (1.5 mm) profile under the weight of a 50-pound motor can play, creating a dangerous backlash. In addition, such structures often deform when transported in the trunk of a car. Always take a profile with a margin along the thickness of the wall, especially if you are new to welding.
The second mistake is that there's no protection for lower unit. Metal on metal is always the risk of scratches that will become corrosion hotspots. Use thick rubber, paronite or special polymeric linings. Also, the fixation from rollover is often forgotten: a narrow base at a high center of gravity is an inverted pyramid that is unstable.
The third mistake is the size, and if you make the stand too wide, you can't fit it in the garage or the door, and if you make it too narrow, you can't get the stability you need. The middle ground The width of the base is equal to or slightly greater than the width of the lower unit in its widest part (usually in the area of the lower unit pipe).
β οΈ Note: Do not use a net-rabitsa or lattice structures without a solid sheet for the upper platform - they can push a lower unit pipe or leave deep dents on the body.
Caring for the stand and motor during storage
Having a stand is only half the battle. It's important to get the motor right. After you get off the boat, let the water drain, then put the motor on the stand. If it's a two-stroke, remember to put it upright or in the drain position if the instructions require it. manufacturerRegularly check the condition of rubber linings on the stand - they should not dry out.
Once a season, it is recommended to update the painting, especially if the stand is in an unheated room or on the street. Metal tends to accumulate moisture, and rust can spread to the parts of the engine.
Properly designed outboard stand dimensions and high-quality installation will keep your equipment safe for years to come, an investment in safety and comfort that pays off without costly repairs to the lower unit and transom. Don't be lazy to take measurements and drawings before welding.
Regular inspection of rubber elements of the stand prevents scratches on the lower unit and preserves the presentation of the engine.
FAQ: Frequently asked questions
Can I use a stand for a 30 hp motor for a 5 hp engine?
Yes, you can. A weight-enhancing stand always has a safety margin. The only thing you can do is check if the pad is too big for a small motor to be limited to just one angle. If you need it, add wooden bars or extra rubber stops for centering.
Which profile is better: square or rectangular?
For racks, it is better to use a square profile (for example, 50Γ50 or 60Γ60), since it equally resists loads from all sides. A rectangular profile (40Γ60) is good for the bottom frame of the base, where width is important, but height is limited.
Do I need to weld a hook to attach the motor to the stand?
This is not necessary, but it is desirable if you plan to transport a boat with an installed motor over long distances on bad roads, a hook or chain will prevent the engine from jumping off the stand in a strong shaking, and for garage storage, the stability of the structure itself is sufficient.
What to do with metal if you canβt paint?
You can use special compounds like "rust-stopping" that convert rust and create a protective layer, and it's also effective to coat with bitumen varnish or liquid rubber, although it's less aesthetic, and the main thing is not to leave the metal unprotected.
Does the type of screw (step or conventional) affect the size of the stand?
The type of screw affects the required height of the stand only indirectly, through the total length of the lower unit. However, stepper screws (for fast boats) are often larger in diameter, so you need to make sure that the lower part of the stand or wheels do not interfere with the size of the screw during installation.