Creation floater In the home, it begins long before the first piece of fabric is in hand, and the foundation of the whole process is the proper cutting of the PVC boat, on the accuracy of which the performance, safety and durability of the future vessel directly depend, errors in the stage of marking the material can lead to skewed cylinders, uneven distribution of load and even tearing the seams under pressure.
Many beginners think that it is enough to simply redraw the drawing on the fabric, but reality dictates its conditions. tensile And the fabric, the shrinkage after heat treatment, and most importantly, the process seams, and without these parameters, even perfectly carved parts won't fit together into a sealed structure.
In this article, we'll look at all the intricacies of the process, from the choice of material to the final cutting of parts. balloon-geometry Why it is important to follow the sequence of actions when working with reinforced polyvinyl chloride.
Selection of material and preparation of the workplace
The first step in preparing for the opening is to choose a quality material. reinforced PVCThe polyester grid base provides tensile strength, and the polymer coating ensures tightness and resistance to ultraviolet.
The density of the fabric varies from 750 to 1100 g/m2. For light cruising models, 750-850 g/m2 is enough, while for boats designed to install the engine or swim on rocky rivers, it is better to choose a material with a density of 900-1100 g/m2.
Can I use a tent fabric?
Awning fabric (one-way PVC) is often used for budget boats; it is cheaper, but less resistant to abrasion and has a lower service life compared to double-sided reinforced material.
The best option is a large flat table or a clean floor in a room with a temperature of not lower than +18 Β° C. Cold air makes the material rigid, which makes it difficult to accurately cut and can lead to deformation of cutting lines.
- π Roulette and long ruler (at least 2 meters) for straight lines.
- βοΈ Special PVC scissors or a disc knife so that the edges do not get jammed.
- ποΈ Alcohol-based markers that are clearly visible on the fabric and do not spread.
Before starting work, the material must be rolled out and allowed to βsit downβ for at least a day, which will allow (eliminate) the internal stresses that arose during the roll roll roll roll roll roll roll roll rolling, and align the geometry of the canvas.
Balloon geometry: theory and practice
The PVC boats are built on understanding how a flat piece becomes a three-dimensional structure, and when you pump air, the flat oval tends to be circular in cross-section, which is why it's so hard to do this. cut-out It is always different from the desired appearance of an inflated boat.
The key here is the balloon diameter inflated. If you're designing a boat with a 30 cm cylinder diameter, the width of the flat piece should be calculated based on the circumference, but adjusted for the shape. Width = (Diameter Γ Ο) + Assumptions.
Use a calculator or Excel table to calculate the circumference length to avoid arithmetic errors when designing large boats.
But it's not enough to calculate the circumference, the bow and stern of the balloon have a complex narrowing geometry, and the patterning method is applied, and the balloon is divided into several cross sections, and each section has its own radius.
And you have to pay special attention to the area where you go from the cylindrical to the cone-shaped, where you get the maximum tension of the tissue, and if you're not cutting right, that's where you most often form. folding, which during operation turn into points of tension and potential breaks.
β οΈ Warning: Never ignore the curvature of the lines when you open the nose cones. A straight line instead of an arc will cause the balloon to go with a screw when pumped, and the boat will scour the water.
Technology of creating patterns and marking
Professional PVC cuts are impossible without first creating precise patterns. Using fabric as a draft is a gross mistake, leading to a lot of waste. The PVCs are made of thick paper, cardboard or, more durablely, plastic film.
The process starts with the application of the symmetry axial line, and all the constructions are from that base, and the inner contour (the seam line) is drawn first, and then the omissions are added, and for the boat cloth, the standard seam tolerance is 30 mm, of which 15-20 mm will be glued, and the rest will ensure the reliability of the connection.
When you move the levee onto the fabric, it's important to consider the direction of the filament of the base. The reinforcement layer has a specific direction of the fibers, and the cut details must be positioned so that the load is distributed along the reinforcement threads. bottom-plate and keel.
βοΈ Check before opening.
Marking on the back (matted) side of the fabric, if possible, so that the marker does not appear on the face glossy surface. The lines should be thin and clear. The thick layer of paint can play the role of a separator during gluing, which is unacceptable.
Calculation of releases and technological seams
The most common mistake in self-manufactured boats is to miscalculate the tolerances. Unlike sewing clothes, where tolerances are minimal, in PVC products, every millimeter matters. The width of the seam affects the area of bonding and therefore the strength of the joint.
There are two main types of joints: a flap and a lining, and cylinders are more commonly used to be flaped or welded, and in the first case, one part overlaps the other, in the second, a gap is left between the edges, which is sealed by a strip of cloth.
The table below shows the dependence of the width of the workpiece on the diameter of the cylinder and the type of seam:
| Diameter of the cylinder (cm) | Length of circumference (cm) | Seam tolerance (cm) | The final width of the cut (cm) |
|---|---|---|---|
| 28 | 88.0 | 4.0 | 92.0 |
| 32 | 100.5 | 4.0 | 104.5 |
| 36 | 113.1 | 5.0 | 118.1 |
| 40 | 125.7 | 5.0 | 130.7 |
It is important to note that tolerances on the end parts (where the balloon connects to the transom or nose bulkhead) may differ from the side parts. coatboard or the installation of a valve system.
The width of the allowance directly affects the weight of the boat: excess fabric is extra pounds that you will have to drag on yourself.
Untie the paioles and decking
If the cylinder cutting requires elasticity, then when working with floorboards (flooring), rigidity and geometry become the main thing. floorboards are usually made of waterproof plywood or aluminum, but their cutting also begins with a drawing tied to the interior of the boat.
When designing flooring, you need to lay gaps between the individual sections. Wood and metal have different coefficients of temperature expansion, and can also change size slightly from moisture. The optimal gap between the sections of paiola is 3-5 mm.
The edges of plywood floorboards must be treated after cutting, soaked in olive oil or special varnish, and then pasted with strips of PVC fabric, which prevents plywood from dissecting and water from entering the structure of the tree.
- πͺ Use an electro-cloth with a file for clean cutting so that there are no chips.
- π Observe right angles, otherwise the flooring sections will not stand in the grooves of the stringers.
- π‘οΈ Donβt forget to make rounds at the corners adjacent to the cylinders so as not to damage them.
The opening of aluminum profiles for stringers (ribs) is made along the inner perimeter of the cylinder. The length of the stringer should be such that it fits tightly into special pockets or is fixed between cylinders, creating a rigid structure.
Nuances of cutting for motor boats
Motor boats require a reinforced structure in the aft section, and the opening here has its own peculiarities: you need to provide additional layers of fabric in the installation area. cross-plate and the engine mounts.
The truncheon is subjected to tremendous vibration and propeller thrust, so the transom gain is cut with the expectation of multi-layer gluing, often using a pie of several layers of PVC of different density, which requires precise alignment of the contours when cutting.
β οΈ Attention: When you cut under a motorboat, be sure to increase the tolerances in the area of attachment of the bolts and ears for fixation. The additional area of gluing here is a matter of safety.
Also for motor boats is characterized by the presence of an inflatable keel of high pressure (HDP). Opening the shell for HVD should be made with minimal tolerances, since the excess material will lead to the formation of bubbles, and the lack of a gap when pumped up to 3-4 atmospheres.
So in conclusion, it's worth noting that cutting PVC boats is a process that requires patience and mathematical precision. Seven times, one cut is the first thing you're talking about, and it's almost impossible to fix the cut-out error, unlike sewn clothes, where you can stitch.
Well done cutting is 80 percent of the success of a quality boat, and the other 20 percent is neat gluing and assembly, and don't neglect to build a cheap fabric trial to work out the technology before you unveil a basic, expensive material.
How to calculate the amount of fabric per boat 3 meters long?
A boat 3 meters long with a 36 cm cylinder diameter would require approximately 9-10 linear meters of fabric with a standard roll width of 1.4-1.5 meters. This is taking into account the cutting of two cylinders, bottom tape, stickers and transom. Always take the material with a margin of 10-15% for defects and errors.
Is it better to cut PVC: with scissors or a knife?
For long straight cuts, it is better to use a disc knife or a construction knife with a new blade and a metal ruler. Scissors can chew the material and give an uneven edge, especially on dense fabric (1100 g / m2). Scissors are only good for cutting out complex small-sized curved elements.
Do I need to make allowances for shrinkage of tissue?
PVC reinforced makes little or no shrinkage in length and width under normal operating conditions. However, when heated (for example, if the boat lies in the sun for a long time), the material may slightly deform. Special allowance for shrinkage is not necessary, the main thing is to observe the temperature regime during gluing.