Buying a 420 centimeter inflatable boat is often a turning point for the owner, and it is this size that is the “golden mean” that allows three adult fishermen to comfortably accommodate or ensure the safe transportation of four people on a walk. PVC boats This class makes it impossible to transport it in the trunk of a passenger car without the risk of damaging the body or the boat itself, at which point the boating is faced with the question of purchasing or manufacturing a specialized vehicle.
Creation trailer yourself, it's not just a way to save money, but also an opportunity to get a product that is perfectly adapted to a particular model of the vessel and operating conditions. Factory counterparts often have a versatile design that can require improvement, while a homemade version takes into account all the nuances from the type of winch to the location of the keel beam. A properly designed frame will ensure a uniform distribution of the load, which is critical for the safety of the transom and bottom when driving on the highway.
In this article, we will take a detailed look at all stages of design and assembly, with a focus on materials selection and safety, which pipes are best used for the frame, how to calculate the axles correctly, and why it is important to consider the full weight of the outfit. A competent approach to engineering will create a reliable approach to the construction of the structure. boat-trailerIt will last for decades without requiring complex maintenance and frequent repairs.
Calculation of dimensions and selection of materials for the frame
The first step in any construction is an accurate calculation. For a boat 420 cm long, the total length of the trailer should be slightly longer to allow for the installation of a noserest and a side reserve. The optimal length of the frame is 450-470 cm. The width of the track should meet standard road requirements, usually 160-170 cm at the outer edges of the wheels, which allows the trailer to confidently hold on to the tractor track. Dimensions of trailer It directly affects its stability and maneuverability.
The basis of the design is the frame. For the manufacture of the carrier frame, the most common is the use of profile pipes of square or rectangular cross-section. The most popular option is a pipe of 40 x 20 mm or 50 x 25 mm with a wall thickness of at least 2 mm. The use of round pipes makes it difficult to weld and dock the units, so a rectangular profile is preferable for home craftsmen. It is important that the metal has anti-corrosion treatment or was galvanized, since constant contact with water is inevitable.
⚠️ Warning: The use of thin-walled pipes (less than 1.5 mm) is not allowed for the carriage of weights above 500 kg. Vibration and dynamic loads during movement can lead to instantaneous destruction of welds and deformation of the frame.
When designing, consider that the center of gravity of a loaded trailer should be located strictly above the axle or slightly shifted forward to the coupling device. This will prevent the trailer from waving at high speeds. For a 420 cm boat that weighs about 300-350 kg in running order with the engine and equipment, one axle (single axle scheme) is quite enough. aluminum-boat or use a massive motor, it is worth considering the option with a two-axle trolley to reduce the load on the road surface and increase stability.
Necessary tools and components
And to build it properly, you're going to need not only metal, but also specialized components that are better to buy ready-made than to make yourself. The key element is the breather, the front of the frame that connects to the car. coupling-headThis is a snag that should match the diameter of the farcope ball of your car (usually 50 mm), and a trailer winch or roller mechanism is mounted on the breather to tighten the boat.
The chassis requires special attention. You will need hubs with bearings, springs or torsion axle, shock absorbers and wheels. For a 420 cm boat, passenger car wheels (R13 or R14) are ideal, which will make it easier to replace in case of a puncture on the way. A braking system for a trailer with a full weight of up to 750 kg is not required by the rules, but the presence of an inertial brake will significantly improve safety when descenting on steep concretes.
Don't forget the boat's attachment elements, which can be carpeted wooden bars or special plastic beds, and the logon is preferred because it fits the hull better. PVC boats They don't store water. They also require ruffle bolts to hold the nose and tanning stops, and all metal parts that come into contact with water must be stainless steel or have a solid zinc coating.
☑️ List of main components
Step-by-step instructions for welding the frame
The assembly process begins with cutting the metal according to the drawings. First, the main rectangle is assembled, the spars, and their length should be the length of the future frame. Between the spars, crossbars are welded that give the structure a rigidity. For a 420 cm trailer, 3-4 crossbars are enough: one under the breather, one or two under the pads and one at the back. Frame welding It should be done with a high-quality seam, preferably on both sides, to avoid twisting the metal.
The breather is welded to the front of the frame at an angle. The standard angle of convergence of the spars is about 20 degrees, which ensures better handling. At the end of the breather, a traction pad is mounted. It is important to observe the alignment: the central axis of the breather should perfectly match the center axis of the entire trailer. Any shift will lead to the trailer moving away.
Procedure for welding:1. The trapping of sparrows on point picks.
2. Checking the diagonals of the rectangle (should be equal).
3. Cross-mounting and gripping.
4. Complete boiling of all knots.
5. Bulgarian seam sweep.
After welding, you have to make a defect, knock the seams with a hammer, remove the slag, and carefully examine them for pores and cracks. If defects are found, they must be re-brewed, only after that the frame can be sent for painting or galvanizing. corrosion-proofing This is the key to a long life of your product, as the trailer will constantly come into contact with water, sand and road reagents.
Before the final painting, degrease the metal with a solvent and apply a primer over the rust. This will increase the paint adhesion and prevent the coating from bloating in the future.
Installation of the chassis and electrics
The axles and springs are mounted on the bottom of the spars. The axle should be positioned so that the centre of gravity of the loaded trailer is 5-10 cm in front of the wheel axle. If the axle is placed too far behind, the breather will pick up, overloading the rear suspension of the car. If too far ahead, there will be a "wafting" effect, dangerous on the road. The springs are mounted through ladders, which must be tightened with the force specified in the bolt specification.
The 420 cm trailer is standard, and includes position lights, stop lights and direction indicators. The 7-pin outlet is used to connect, the wiring is better placed inside the profile pipes or in special corrugated tubes to prevent damage to the insulation. All connections must be carefully insulated and protected from moisture, because water and electricity are dangerous combinations.
Pay special attention to the tightness of the hubs. When launching a boat into the water, the hubs can be submerged. Use double-cuffed glands or the E-Z Lube system, which allows you to lubricate bearings without disassembling the hub. Regular checks of bearings and lubricants are a prerequisite for safety. Scream or wheel hum indicates the need for chassis maintenance.
| Parameter | Value for boat 420 cm | Note |
|---|---|---|
| Total mass of trailer | 750 kg | Category of rights “B” |
| Number of axles | 1 | Optimal for PVC |
| Type of wheel | R13 / 175/70 | Passenger car standard |
| Material of the pawns | Plywood + carpet | Budgetary option |
Spades and winch equipment
When the frame is ready and the chassis is installed, it is time to equip the boat space. Inflatable vessels of 420 cm long, composite beds are ideal. They are transom beams on which boards or plywood sheets are stacked upholstered with soft carpet. This design prevents cylinders from pressing and provides ventilation to the bottom. The distance between the beds should be calculated so that the keel of the boat does not touch the metal frame.
The bow is fitted with a winch. For a 420 cm motored boat, a traction winch with a force of 500-700 kg is optimal. The mechanism is mounted on the cross of the breathed. The winch cable should have a carbine or a pome to attach to the bow loop of the boat. It is also recommended to install guides (conductors) on the sides of the winch, which will help to position the boat correctly when loading, especially in windy weather.
⚠️ Warning: Never leave the boat fixed only to the winch cable during transportation. Be sure to use a safety chain or belt, thrown over a transom and fixed to the frame, in case of a cable break.
To hold the boat in the marching position, use transom stops and side restraints, which prevent the vessel from moving to the sides and jumping on the roughness of the road, all points of contact of metal with PVC should be smoothed and closed with soft material. Safety of transport It depends on the reliability of these nodes.
The secret of the durability of pawns
Use moisture-resistant plywood at least 18 mm thick for the pawns. Treat the tree with olifer or special wood oil before carpeting, and this will prevent the base from rotting even with constant contact with water.
Registration and legal aspects
A homemade 420 cm boat trailer is subject to mandatory registration with the traffic police, like any other vehicle. To do this, you will need to undergo a certification procedure or obtain a certificate of safety of the structure in an accredited laboratory. Without the relevant documents (PTS, certificate of registration), the operation of the trailer is prohibited and threatens with a fine and sending the vehicle to the parking lot.
The process of legalization can be complex and costly. Many craftsmen go by buying an old trailer with documents and completely reworking it to suit their needs. It is a legal way to get the frame of the right size with ready-made papers. In this case, the PTS is modified if they are significant, or the trailer simply passes a technical inspection as a restored vehicle.
When operating, remember that the speed of movement with a trailer is limited. In settlements - no more than 60 km / h, on country roads - no more than 90 km / h Exceeding speed with a trailer, especially with a sailing load such as a boat, can lead to loss of control. Traffic rules require that the trailer's position lights be in good working order and visible to other road users.
Legalizing a homemade trailer through a lab is expensive, so buying an old donor trailer with documents is often a more rational economic decision.
Frequently Asked Questions (FAQ)
Do I need an E-Right to Trailer for Boat 420?
No, if the total mass of the trailer does not exceed 750 kg. In this case, the rights of category "B" are sufficient. If the mass of the trailer is more than 750 kg, but the sum of the mass of the car and the trailer does not exceed 3,500 kg, the rights "E" may also not be required, but this depends on the specific mass of your car. For a standard boat 420 cm with a light engine, the mass rarely exceeds 500-600 kg.
What is the best paint to paint the trailer?
The best way to use specialized enamels for metal structures, resistant to ultraviolet light and mechanical damage, well-established hammer paints and epoxy soils, before painting, it is mandatory to clean the metal to shine and degrease.
Can I carry a boat with the engine raised?
Technically, if the dimensions allow and the motor is securely fixed, however, for a boat of 420 cm this can create problems with the centering and sailing. It is recommended to transport the motor separately or lowered, if the design of the transom stop allows the boat to safely lock in this position.
How often should the bearings of the hubs be lubricated?
It is recommended to carry out preventive lubrication of bearings once a year or every 10,000 km of run. If you often immerse the trailer in salt water, the service intervals should be reduced to once a season using lubricants that are resistant to water washing.