Making a non-ferrous boat at home is an ambitious task that requires precision and patience. Many aquatic motorists are wondering how to rivet an aluminum boat to get a reliable and durable hull that can withstand storms and impacts on rocks. Self-assembly allows you to save a lot of money and get a vessel with customized specifications that are not available in mass production.
Aluminum is valued for its lightness, corrosion resistance and ease of processing, but working with it has its own technological nuances. Rivet It's the main method of joining sheets in shipbuilding, because welding requires expensive equipment and high skill, and a properly assembled riveted hull can last for decades without requiring complex maintenance, if you first meet all the stages of the technology.
Before you start to use tools, you need to understand that the success of a project depends on the quality of preparation and drawings. Mistakes made during the cutting of metal or marking holes will be almost impossible to fix without losing the strength of the structure. In this article, we will discuss the entire process in detail, from the selection of materials to the final sealing of the seams.
Selection of material and preparation of drawings
The foundation of a quality boat is the right alloy choice, and shipbuilding is not suitable for ordinary household alloys, which can be found in any construction market. aviationparticularly stamps AMG5M or AMG6MThese alloys have high strength and excellent resistance to seawater, unlike technical aluminum, which will quickly burst under load.
The thickness of sheet metal is selected depending on the size of the future vessel. For the bottom, usually use a sheet 3-4 mm thick, and for the sides and decks it is enough 2 mm. If you have purchased a hard sheet, it will have to be annealed yourself, which requires strict temperature control.
⚠️ Warning: Never use D16T dural sheets for construction of a boat without special protection, which is subject to severe electrochemical corrosion in the water and will quickly collapse, which can lead to an emergency afloat.
During the design phase, you need to create or find proven drawingsThe geometry of the hull determines the performance and stability of the boat. Even a slight deviation from symmetry can cause the boat to scour the course or have a differentiation on one side, all dimensions must be transferred to paper or to a CAD program with millimeter accuracy.
Where can I find the verified blueprints?
The most reliable way to use drawings from specialized magazines "Boats and Yachts" or "Modelist-designer" for the past years, or to purchase licensed projects from shipbuilding design bureaus. Drawings from the Internet often contain errors in dimensional chains.
Required tool and supplies
The quality of the riveted joint depends on the tool you use, and you'll need not only a hand tool to work, but also specialized devices to prepare the holes. rivetwhich must be made of the same material as the skin or of a softer alloy so as not to cause electrochemical corrosion.
The diameter of the rivets is chosen based on the thickness of the sheets that are joined. The formula is usually used: the diameter of the rivet is 2-2.5 thickness of the thinnest sheet. For boat hulls, rivets with a diameter of 4 mm and 5 mm are most often used. Too thin rivets will not ensure tightness, and too thick can deform the thin metal when installed.
The list of equipment required includes:
- 💠 A drill with a set of metal drills (cobalt or diamond-sprayed) for clean cutting.
- 💠 Zenker or zenkovka for preparing holes under the secret heads.
- 💠 A pneumatic rivetor or hammer with hand riveting crimps.
- 💠 Strubsins and temporary fixtures for fixing sheets.
Special attention should be paid to the preparation of the edges. All sections should be perfectly smooth, without burrs, which can become foci of corrosion or disrupt the density of the adhesive sheets. Hermetic for seams should be specialized, designed for constant contact with water and ultraviolet light, for example, based on polyurethane or thiokol.
Use drills with a sharpening angle of 135 degrees for aluminum – they less “bitten” the metal and give a cleaner hole without ragged edges.
Technology of cutting and flexible sheets
The manufacturing process begins with the transfer of dimensions from the drawing to the metal, and the best marker for marking is the metal marker, since scratches of the core can become the starting point of corrosion processes. Open it. It's done with the allowances on the connection, and if you're planning to do the overlapping, you need to add an extra sheet width.
Aluminum sheets are flexible, and they require precision. Aluminum has the ability to spring back to its original state after deformation. To get the exact angle of the side or the forehead, the metal often has to bend to an angle that is higher than the calculated angle given the elasticity of the material. Flexibles use bendables or powerful vise with wooden pads.
When you form complex contours, like the cheekbones or the nose, the metal is heated, but here lies the main danger: overheating of aluminum above 400 degrees leads to loss of its strength specifications and meltingHeating should be done carefully using a gas burner and controlling the temperature by color or special thermoindicators.
⚠️ Warning: When bending sheets thicker than 3 mm without heating, there is a high risk of cracking the fold area. Always check the condition of the metal after bending with a magnifier for microcracks.
After the flexion, all the pieces are assembled into a "pretzel"; the sheets are temporarily attached with rods or screws to check the geometry of the case, and if all the lines converge and the gaps between the sheets are minimal, you can start drilling holes under the permanent fixture.
Drilling and jellying process
Drilling is the most important step in determining the strength of the entire knot. Holes should be located strictly perpendicular to the surface. The slope of the drill will ensure that the rivet cap does not press the sheet tightly, and water enters the gap. The openings are usually 3-4 rivet diameters, but not more than 100 mm to ensure tightness.
To obtain a high-quality connection, the edges of the holes are treated serpentThis allows the rivet head to be drowned in the same level as the surface of the skin, which improves the hydrodynamics and appearance of the boat. The depth of the jellying should be strictly controlled: too deep a sample will weaken the connection, and a small one will not allow the fastener to plant tightly.
Table of correspondence of diameters of drills and nuclei:
| Rivet diameter (mm) | Drill diameter (mm) | Corner of the serpent | Head type |
|---|---|---|---|
| 4.0 | 4.1 - 4.2 | 90° | Secret. |
| 5.0 | 5.1 - 5.2 | 90° | Secret. |
| 6.0 | 6.2 - 6.4 | 120° | Semi-circular |
| 4.0 | 4.1 | - | Convex |
It's important to remove the metal shavings immediately after each hole is drilled, and if it gets between the sheets, it will break the tightness and create a galvanic pair that accelerates corrosion, and after drilling, the holes must be degreased with a solvent before applying the sealant.
Techniques for performing riveting work
The riveting process itself requires skill. Before you put the fastener on the joint, you put a layer on it. sealantThe rivet is inserted into the hole, and it is immediately broken open, and if you use an exhaust rivet, you have to wait for the characteristic click or break of the rod, indicating the complete formation of the head.
When you use a hammer and a mint, two people do the job: one holds the crimp on the back side (supports the head), the other clatters the tail. The blows must be strong, but not excessive, so as not to flatten the metal around the hole. The riveting sequence from the center of the connection to the edges to squeeze out the excess sealant and air.
Quality control of each joint is mandatory, visually checks the density of the hat fitting, tapping on the finished row of rivets should not emit a rattling sound that indicates the presence of voids. Tightness The seam is provided precisely by tight pressing of the sheets to each other with a gasket of sealant.
- 💠 Apply sealant on both connected surfaces with a thin layer.
- 💠 Insert the rivet immediately, not allowing the sealant to dry ("grab").
- 💠 Extracted excess sealant remove the spatula before it hardens.
Pay special attention to the angles and the brangouts, where the stress concentration is maximum, so the pitch of the rivets can be reduced, and the diameter can be increased. Don't skimp on the fasteners in the loaded nodes.
☑️ Control of riveting seam
Seam sealing and finishing
Once all riveting is done, the boat needs to be tested for leakage, which means that the hull is turned over and filled with water, or the seams of the hose are poured on the inside, watching for drops from the outside, and the places of leaks are marked with a marker for subsequent repairs.
The defects are repaired by drilling the problem rivet and installing a new one larger in diameter, re-applying the sealant, and after successful testing, all the seams are cleaned of the sealant residue, degreased and grinded, and the metal surface is ready to be painted.
Aluminium is protected by a special paint for boat hulls containing zinc or other anti-corrosion additives. Before painting, the metal is often chemically etching or anodizing to improve adhesion. A quality paint coating extends the life of the boat for decades.
⚠️ Warning: Do not use lead-based paints in combination with aluminum alloys. Lead and aluminum form a dangerous galvanic pair, which will lead to rapid corrosion of the metal under the paint layer.
Finishing includes the installation of floorboards, cans, switches and attachments, all fasteners on deck should also be planted on a sealant, and only after all materials are fully assembled and dry can the boat be launched for sea trials.
The main secret of the durability of riveted boats is not in the thickness of the metal, but in the quality preparation of the edges, the correct step of rivets and the use of compatible materials.
Can an aluminum boat be riveted with conventional steel rivets?
It's not recommended. Steel and aluminum have different electrochemical potentials. In seawater or even river water, this will cause the aluminum to quickly corrosion around the steel rivet. Use only aluminum or brass rivets.
Which sealant is best for aluminum boats?
Polyurethane sealants (such as Sikaflex-291i) and thiocol mastics are the best, and they retain elasticity under vibrations and temperature changes without cracking with time.
Should I burn aluminum before flexible?
If you use sheets in solid state (T index or no index), annealing is a must to prevent cracks when bending. The sheets with the index M (soft) have already been heat treated and ready to go.
How to remove a broken rivet without damaging the hole?
Carefully drill the center of the rivet with a smaller diameter drill, then carefully remove the remains of the hat. Do not drill the main hole immediately so as not to disturb its geometry.