An inflatable floor boat (BBB) or hard decking (BB) is a reliable craft, but even the strongest PVC is subject to wear. The keel, which is a longitudinal element of rigidity and protection, often takes on impacts on a rocky bottom, concrete frames on descent or sharp objects on shore. Damage to this element is not just a cosmetic defect, but a direct safety threat, as the geometry of the vessel is disturbed and there is a risk of puncture of cylinders.
Many owners, when they see the keel tape peeled off or torn, panic, believing that the boat is now only suitable for recycling or expensive factory repairs. keel-recovery It's very feasible to do it in a garage, if you follow the technology, and the key is the right materials and the temperature, so if you just put the first glue on the hole, the water will inevitably get to the cord, and the boat will lose its tightness at the worst possible time.
In this article, we will discuss in detail the process of replacing or gluing the keel, paying special attention to the nuances of working with polyurethane adhesives. double-component Often, one-pieces are preferred to clean the surface properly without damaging the PVC protective layer, and to provide a seam with a durability comparable to that of a factory seam, which takes up to 70 percent of the time to complete, but that is what determines the final result.
Selection of adhesive composition and materials for repair
The first and most critical step is to find the right glue, and the market is full of products, but for the best of them, PVC materials Most modern boats are made of five-layer polyurethane-coated fabric, so the glue must be polyurethane, and using chloroprene-based adhesive (often yellow with a pungent odor) for these boats is considered a mistake, because it forms a less elastic seam that can detach when bent.
The best choice is a two-component polyurethane glue, which consists of the adhesive and hardener (catalyst). Mixing the components triggers an irreversible chemical reaction, so you need to prepare the mixture immediately before applying and in the amount that you will have time to consume in 30-40 minutes. Single-component adhesives also exist, but they require ideal humidity and temperature conditions for polymerization, which is difficult to provide in a garage or outdoors.
In addition to the glue itself, you will need additional materials. To degrease the surface, use acetone or a special degreasing agent (for example, acetone). galosha or 646 You will also need P220-P320 grain sandpaper, a dryer for construction work (domestic heat is not suitable), and possibly a new keel tape if the old one has become obsolete.
When you buy glue, pay attention to its elasticity after drying. The keel seam is constantly under tension: when you inflate a boat, the keel is pulled, when you move along the wave, it acts as a shock absorber. If the glue is too rigid, it will crack. If it is too soft, it will not withstand mechanical friction against the ground. Wurth, Texacol or high-quality domestic analogues developed for PVC.
Surface preparation: cleaning and degreasing
The quality of the gluing depends on 90% of the surface preparation. Even the most expensive glue will not stay on a dirty, greasy or smooth surface. The first thing to do is to thoroughly wash the boat, especially at the site of damage, using warm water and detergent. After washing, the boat must completely dry, because moisture is the main enemy of polyurethane glue.
Then there's mechanical cleaning. You need to remove the top glossy layer of PVC to open the pores of the material to better penetrate the glue. Use sandpaper, but don't overdo it: your goal is to create a matte, rough surface ("velvet"), not to pull the fabric down to thread. Cleanup. It's done in a circular motion with a little pressure, and you can treat both the boat itself (the place of sticking) and the back of the keel tape.
After cleaning, you need to degrease the surface, soak the clean, lilaless rags in the solvent, and thoroughly wipe the cleaned areas, which will remove the dust left over from the sandpaper and the fat spots from the fingers. Important: After degreasing, touching prepared areas with your hands is strictly forbidden, because the skin fat will instantly reduce adhesion.
If there is any old glue left on the boat, it should be removed, so you can carefully heat the area with a hair dryer and roll it softened with your fingers or a blunt knife. Mechanical scraping of cold glue can damage the fabric of the boat, so the thermal method is preferable. Make sure the surface is completely clean, dry and matte before moving to the next stage.
☑️ Preparation for gluing
Technology of applying glue and gluing
The gluing process requires careful timing. If you use two-part glue, mix the base and hardener in the proportions specified in the instructions (usually 100:4 or 100:10, but better weigh on an electronic scale). Mix the composition carefully until uniform. Apply the glue in a thin uniform layer on both the adhesive surfaces: on the boat and on the keel tape. Use a brush or a spatula.
After applying the first layer, let it dry. The drying time depends on the temperature and the type of glue, usually 15-30 minutes. The glue should stop being sticky to the touch, but not dry completely. It is often recommended to apply the second layer for better adhesion. After the second layer, we wait for the dried again to the "stick" state (when the finger does not stick, but the surface is sticky).
Connect the surfaces, press tightly, roll the roller from center to edge to drive the air out. Now the hair dryer comes in. Warm up the chemical processes in the glue. Heat the seam to 50-70 degrees (PVC should not melt or deform, become too soft). Warm up evenly, without delay at one point. After warming up, roll the seam carefully again with a hard roller with effort.
There's the term "lifetime" of glue, which is the period during which the glue can be bonded together after application, and if you hold the glue over and it dries into the crust, it won't work. If you hurry, the glue will just smear and not catch. Temperature conditions in the room should be not lower than +15 ° C, otherwise polymerization may not go or pass incorrectly.
Use of construction hair dryer: temperature regime
A building hair dryer is an indispensable tool for PVC repair. However, many beginners are afraid to use it or, conversely, overheat the material. PVC melting point is about 220-250 degrees, but already at 80-90 degrees it begins to soften and deform. So the task of the master is to find a balance: heat the glue before activation, but not melt the fabric.
The optimum temperature of the jet of air to activate polyurethane adhesives is 60-80 degrees. Keep the hair dryer 2-3 cm from the surface and constantly move it. Do not hold the flow of hot air at one point for more than 1-2 seconds. If PVC began to shine stronger than usual or went bubbles - you overheated the material. In this case, you need to immediately stop work and let the boat cool down.
You can tell if the seam is ready to roll by looking at it, and if it's heated properly, it becomes glossy and slightly fluid, and when rolled, it should be even, without bloating. Important: You need to roll it right after you warm it up, while the glue is hot and elastic, and if you heat up a large area and then start rolling it for a long time, the temperature will drop and the gluing quality will deteriorate.
You can use a contactless thermometer (pyrometer) to control the temperature, but experienced craftsmen often check the heating with the back of the palm (caution!) or by changing the plasticity of the material. Remember that in winter or in a cold garage, the boat will cool faster, so you will have to work faster, perhaps heating the boat itself before work begins.
Comparison of types of adhesives for PVC boats
To make a final decision on the materials, let's compare the main types of adhesives available on the market, and understand the differences between them will help avoid mistakes and spend money on the wrong composition.
| Type of glue | Basis | Drying time | Strength of the seam | Temperature requirements |
|---|---|---|---|---|
| single-component | Polyurethane | 24-48 hours | High. | Requires humidity >60% |
| Two-pronged | Polyurethane + Hardener | 12:24 hours. | Maximum | Stable +15°C and above |
| Chloroprene | Neoprene/Rezina | 24 hours. | Medium | Not critical. |
| Universal. | Mixed | Other. | Low/Medium | Depends on the composition. |
As you can see from the table, polyurethane They're good at strength and speed, but they require more precise adherence to the technology. One-pieces are good at not mixing anything, but they're humidity-driven: they can dry for weeks in dry weather. chloroprene adhesives (often marketed as "inflatable boats") are good for old Soviet rubber or rubber-coated cloth boats, but they're a bit weak for modern PVC.
And we also have special remixes that come with a boat, which are usually small tubes with single-piece glue and a piece of fabric, and they only last for a small puncture. There's not enough volume in the remix to stick the keel, and the properties of the adhesive can be inferior to professional counterparts. So for serious repairs, it's better to buy individual components.
⚠️ Warning: Never use expired adhesives. Polyurethane crystallizes over time and loses its properties even if the packaging has been closed. Before buying, check the date of production on a tube or can.
Drying, polymerization and quality control
Once you have rolled the seam and removed the hair dryer, the repair process does not end. The glue should gain strength. Primary polymerization takes about 12-24 hours, but full strength is achieved in 3-5 days. During this time, the boat cannot be inflated, subjected to loads, urinated or left in the cold / sun.
Leave the boat in a warm, dry room at room temperature. It is advisable to put a load (such as a sandbag or a book) on the glue site to ensure that the edges fit tightly during freezing. The pressure should be uniform, but not excessive, so as not to squeeze all the glue out of the seam.
After 24 hours, you can do a primary check, try carefully to bend the edge of the keel tape (no fanaticism), if the glue holds dead and the surface is smooth, the process was successful. If the tape is moving away and there are traces of glue on it, then the technology is broken (poor cleansing, cold, moisture), in which case you have to redo the work, completely removing the old layer.
The first outing after the repair is better to make in 3-4 days, observe the behavior of the boat on the water: whether there are swelling, whether the keel does not depart when the wave is loaded. Properly glued keel is the same as the boat itself, so rushing during the drying stage is unacceptable.
Can I put the keel in the cold or in a damp garage?
It's not recommended. Polyurethane adhesives require temperatures above 15°C and low humidity. In the cold, the glue freezes and doesn't polymerize, becoming brittle. In damp, moisture reacts with the glue components, causing the suture to foam and loss of strength. If there's no other option, you need to organize a "greenhouse" or use powerful heaters and air dehumidifiers, but it's complex and energy-intensive.
How to replace a building hair dryer if it is not?
It's almost impossible to replace a hair dryer. Household hair dryers only give a temperature of 50-60 degrees, which is not enough to activate the glue (you need 70-90 ° C and a powerful flow); boiling water is useless to heat it quickly and does not give the desired surface temperature. You can try to use a very powerful industrial heater by pointing it at the seam, but controlling the temperature will be difficult. The best option is to rent a hair dryer or buy a low-cost model that will be useful in the household.
What if the keel is partially unstuck (only the nose or heel)?
If only the edges (heel or forespig) are unsticked, don't peel off the entire tape, clean the detached area carefully, degrease it and glue it, following the technology, the main thing is to make a qualitative transition (flush) between the old glue and the new one, clear the border of the old glue, so that the new portion of glue will fall on the prepared surface and partially on the old layer, ensuring monolithicity.
⚠️ Attention: Do not try to speed up the drying of glue by leaving the boat in the direct sun or near the battery. Local overheating can cause PVC deformation and bubbles in the seam. Drying should take place at room temperature in the shade.