Inflatable boat owners often encounter the term “recession,” especially when it comes to the condition of the transom part of the boat. Boat recession It is a specific design defect or process element (depending on the context) associated with a violation of the geometry of the transom plate, most often expressed in the pressing, deformation or formation of cracks in the places of attachment of the transom to the main body.
The deformation is not a wasteland, but a complex interaction between mechanical loads and materials. When you install a motor that is above the permissible weight, or when you are in a long-term operation under aggressive conditions, the structure of fiberglass or plywood hidden in the cylinder begins to break down. Polyvinyl chlorideThe stain that's made of the balloon has a certain elasticity, but the rigid insertion inside it doesn't, and it's this imbalance that creates what in the professional world is called a transom recession.
In this article, we will take a closer look at the physics of the process, examine why standard amplification methods sometimes don’t work, and propose a step-by-step geometry recovery algorithm. Repairing the recession It requires not only technical skills, but also an understanding of the chemistry of bonding processes to ensure the longevity of the result, you will learn how to diagnose hidden damage and what tools are really needed for quality repair.
Physics of the process: what happens to the material
To understand how to fix a problem, you have to understand the root of the problem. The trawler of any inflatable boat is a sandwich structure. Inside the balloon is a rigid stove (usually made of moisture-resistant plywood or composite), which is reinforced from the outside by linings. When you put the motor on, the tractive force is transferred to this stove. If the load is distributed unevenly, there is a point of maximum voltage, where it begins. transmutation.
Materials behave differently under load. The glass, which is often reinforced on the outside, works to stretch, but does not resist point-pressing. The plywood, swelling from moisture or losing the binder from vibration, changes its volume. Clay.The sludge used in manufacturing can dissipate if the technology is disrupted or depleted, all of which together produce a cavity or crack, which is called a recession.
⚠️ Attention: Operation of a boat with a damaged transcen is strictly prohibited. Increased deformation can lead to engine detachment at full speed, which can lead to loss of the boat and injury to people.
It's important to distinguish between elastic and plastic deformation, and if you take the motor off, the transom returns to its original state, you're in the elastic strain zone, and if the dent or curvature remains, it's a plastic deformation that indicates irreversible changes in the structure of the material, and that's when intervention is required. Rebuilding geometry Early on, it takes less time and resources.
Technical reference
Material Fluidity Limit: Most structural plastics and composites used in shipbuilding are at a local heating or long static load of more than 70% of the destructive load, which is why you can not leave a heavy motor on the transom of the boat in a pumped state for a long time, especially in hot weather.
The main causes of defects
Why does a recession happen? It's often the owner who overloads the engine, and manufacturers give the maximum power for a reason, and exceeding that limit by even 1 or 2 horsepower creates a tremendous lever effort per transax plate. transom overload The number one reason that leads to the rapid failure of even the highest quality boats.
The second factor is the wrong outboard motor, where if the motor is fixed too high or too low, the thrust angle changes, and the force vector starts to work not on the boat moving forward, but on the break of the transom, and the quality of the boat assembly also plays a role: using cheap glue or breaking the temperature when glued in the factory causes the layers to move away from each other under load.
- 🚫 Exceeding the permissible power of the outboard motor specified in the product passport.
- 🌊 Operation at high speeds in conditions of a strong wave, when the impacts of water fall on the plane of the transom.
- 🔩 Incorrect tightening of the engine rods, creating local pressure points.
- 💧 The penetration of moisture into the transom plate, swelling of wood and destruction of the structure.
And the temperature factor is also worth mentioning, and in the sun, black or dark gray transoms are heated much more than the environment. PVC It softens, and the rigidity of the structure drops. If you give it full gas at that moment, the probability of a recession increases many times, so in hot weather, it is recommended to let the boat cool down or shade the transom part.
Diagnosis: How to identify hidden damage
A thorough diagnosis is required before any major repairs are undertaken, and visual inspection is often not enough, as microcracks can hide under a layer of paint or gelcoat. Transnant defect It starts with a tactile inspection, and you run your hand across the surface, looking for bumps, bumps, or troughs, and any change in the terrain is a signal.
Use tapping. Light impacts with a knuckle or plastic tool on the surface of a transom will help detect the stratifications. The sound over the whole area will be loud and clear, while over the stratification zone or the inner void it will become deaf. damage with high precision.
Also, look at the condition of the fasteners, if the engine rods leave traces where they were not before, or if the hinged transom appears to be lufty relative to the main cylinder, these are sure signs that the internal structure is broken, and in some cases, partial gluing of the reinforcing tape is required to assess the condition of the base material.
| Method of diagnosis | What we looking for | Tool. | Sign of a problem |
|---|---|---|---|
| Visually | Cracks, bloating. | Lupa, flashlight. | Geometry disturbance, white stripes |
| tactile | Uneven, soft, soft. | Hands. | Trenches, lack of rigidity |
| Acoustic | Separation | Plastic hammer | Deaf sound when tapping |
| A backlash test | Shifting of nodes | The hinged transom | Scream, free ride under load |
If you find that the damage affects not only the outer layer, but also the inner structure, you need to assess the scale of the disaster. Critical damage is considered, in which the deformation affects more than 30% of the area of the transom plate or is accompanied by rupture of fibers of the fiberglass tissue through. In such cases, a simple cosmetic repair will not help, you will need a complete digestion of the transom.
Preparation for repairs: tools and materials
Quality recession You don't have to do it without the right preparation. You need not only the desire, but you need a specific set of materials, and you'll have to use a hardener epoxy resin, because it's the one that provides the best adhesion and strength for fiberglass and wood. Polyurethane adhesives are less effective because of the low stiffness of the seam.
Reinforced fiberglass will require different density, a thin spider will go to the first layers to penetrate microcracks, and a dense structural fabric to create a power frame, and you also need acetone or a special degreasing agent to prepare the surface. Sandpaper different grains (from P80 to P240) are needed for cleaning and grinding.
☑️ List of required materials
Don't forget personal protective equipment. Epoxy resin and acetone vapors are toxic, so a respirator is a must. Work better in a well-ventilated room or outdoors, but not in direct sunlight to control the life of the mixture. Also prepare rollers to roll layers to remove air bubbles.
If it is a question of restoring a wooden base, a new plywood or an epoxy compound with a microsphere may be required to fill the voids. It is important that all materials are compatible with each other. The use of “popular” methods, such as sealing with sealants or polyurethane foams, is unacceptable in this case, since they will not provide the required rigidity.
Recovery Technology: Step-by-step instructions
The recovery process begins with a thorough cleanup of the damaged area, removing all detached fragments, old paint and gelcoat to a clean, healthy material. Surface cleaning It's made with sandpaper, and it's made with a gradual reduction in grain content, and the boundaries of the area to be repaired should be smooth, without any sudden elevation changes.
After mechanical cleaning, the surface is degreased. This is a critical step: any fat film will reduce the adhesion of the epoxy resin, and repair will go to waste. Rub the surface with pure rags soaked in acetone and let it dry. If there are cracks in the fiberglass, they need to expand (drill the endings of cracks) to stop them from growing.
Then comes the main step, lamination, a layer of epoxy, a glass cloth, and a carefully rolled roller to remove air, which is repeated several times until the desired thickness and strength is gained, and it is important to observe the time intervals between the layers specified by the resin manufacturer.
⚠️ Warning: Do not try to speed up the drying process with a hair dryer or heater. Dramatic heating can lead to boiling of the resin, the formation of bubbles and a decrease in the strength specifications of the finished product.
The final stage is grinding and painting, and after the resin is completely polymerized (usually 24 to 72 hours), the surface is grinded smoothly and coated with a protective varnish or UV-resistant paint, which will protect the repair from burnout and water exposure. Finishing It also improves the aesthetic appearance of the boat.
Use microspheres (glass balls) mixed with epoxy resin if you need to fill deep depressions, which will prevent excessive heating during polymerization and reduce the weight of the patch.
Prevention and extension of service life
To avoid a boat recession becoming a constant problem, you need to follow the rules of operation. First of all, watch the weight of the engine. If the passport power of the boat is 5 hp, do not put 8 hp on the bench. Compliance with loads Also, try not to leave the boat with the engine suspended for a long time, especially in the heat.
Regularly inspect the condition of the transom plate. Early detection of small defects allows you to eliminate them quickly and cheaply. Lubricate the rubbing parts with silicone grease to prevent mechanical damage to the protective layer. Keep the boat straightened, without claws in the area of the transmolator.
- 🛡️ Use transom wheels to facilitate descent so as not to put weight on the motor during maneuvers.
- 🧼 Wash the boat with fresh water after each outing to the sea to wash away the salt corroding the material.
- 🌡️ Avoid sudden temperature changes during storage (for example, from a cold garage immediately in the sun).
- 🔧 Regularly tighten the fastener bolts of the hinged transom, if the design allows.
Proper care of the boat is not just washing, it is a set of measures to preserve its technical specifications. Inflatable boats They require attention, but they give you years of safe operation, and investing time in prevention always pays off without expensive repairs.
Sooner or later, any boat undergoes a recession with active operation, but competent care and the correct selection of the engine postpone this moment for years.
Can I put a squirrel in the cold?
Epoxy resins and most PVC adhesives require temperatures above +15°C for normal polymerization, and in cold weather, the reaction will either not go away or will not go away completely, and the seam will be brittle.
How much dried epoxy on the transom?
The primary grasping time is 4-6 hours, but the full strength of the resin gains after 24-72 hours at a temperature of +20 ° C. Do not load the transom before the expiration of this time.
Do I need to remove the transom plate for repair?
90 percent of the time, no. Repairs are done from the outside, and removal of the stove is only required if the internal plywood is rotting completely or if the deformation is so severe that the base needs to be replaced.
How to replace glass during repair?
Nothing is complete. Carbon fiber is stronger, but it's more expensive and it requires different technology, base fabric or gauze will not give you the necessary strength, glass is the best option for home renovation.