In the world of small swimming equipment for many years, there was a division into two camps: fans of classical aluminum and enthusiasts of soft inflatable boats made of PVC. low-pressure polyethyleneThis material, often referred to simply as HDPE or HDPE, is fundamentally changing the way a reliable fishing and recreation vessel should be.
Many aqueous motorists still confuse HDPE with ordinary plastic that cracks from hitting a stone, or with PVC, afraid of sparks. In fact, rotational molding technology allows you to create all-body products of incredible strength. The molecular structure of polyethylene used in shipbuilding provides the material with “shape memory” and high impact resistance even at extremely low temperatures. This feature makes such boats indispensable in the harsh conditions of the north or when working with ice.
In this article, we will discuss the physical and chemical properties of the material in detail, compare it with competitors and answer the main question: whether such a vessel is right for you, you will learn why some models weigh more aluminum counterparts, but are considered more tenacious in operation.
What is PHD and how do boats?
Low-pressure polyethylene is a thermoplastic polymer produced at low pressure using catalysts. Unlike conventional high-pressure polyethylene (which makes bags), HDPE has a much denser structure and high mechanical strength. Shipbuilding polyethylene is used to make boats, often with the addition of ultraviolet stabilizers, allowing the hull to withstand the aggressive effects of the sun for years without losing properties.
The process of creating the casing is called rotational molding (rotational melting). Unlike injection molding, there is no high pressure that creates internal stresses in the material. The HDPE powder is poured into a metal matrix shape, which is then rotated in the furnace. The molten plastic is evenly distributed across the walls, creating a metallic matrix powder. monolithic It's the absence of seams that is the key to reliability, because it eliminates the risk of leakage in the joints.
The technology allows complex geometry housings with integrated elements. For example, knobs, cans (seats), and even transom attachment elements can be part of a whole with the body, rather than welded or glued parts. This significantly reduces the complexity of the assembly and increases the overall rigidity of the structure.
Why doesn't the HDP melt right away?
The melting point of low-pressure polyethylene is about 130-135 ° C, but it begins to soften and lose shape already at 80-90 ° C. However, due to the high heat capacity of the material, short-term exposure to a spark from a fire or cigarette does not lead to instantaneous burning, as in the case of a thin film of PVC.
It is important to understand that rotary It's not just plastic, it's a high-tech material that often outperforms many metals in its survivability, and it doesn't get residual deformation like aluminum, but rather tends to return to its original state through elasticity, a property that's critical for boats that are designed to land on unequipped shores or work in ice crumbs.
Key Advantages of PND Boats
The first and most obvious advantage is absolute unsinkability combined with high buoyancy. The density of polyethylene is less than the density of water, so even a fully watered boat will not sink, but will stay afloat. This gives a huge advantage in safety compared to (glass) or aluminum, which require the installation of additional buoyancy blocks, which over time can lose their tightness.
The second important aspect is resistance to abrasive wear: the bottom of the PHD boat is almost impossible to scratch with sand or pebbles in a way that affects its functionality. If the aluminum bottom eventually appears furrows, and the PVC thins the lacquer coating, the plastic case simply becomes matte, maintaining its tightness. Wear resistance The material allows you to use such boats for crossings, working in shallow waters and even as pontoons.
The third advantage is chemical inertia. Polyethylene is not susceptible to corrosion, rotting, and most corrosive environments. Salt seawater, gasoline, oil, fish mucus, or fertilizers, nothing can damage the material's structure. You don't have to worry about accidentally spilled fuel mix destroying the bottom, as it can happen with some plastics or rubber.
Use a soap solution to check whether the joints are tight (if they are in the accessories) or the integrity of the body after a strong impact. Although the HDPE is monolithic, the loads can create microcracks at stress points that are easily detectable by bubbling points.
And it's also great noise insulation, because polyethylene can quench motor vibrations and wave noise much better than thin sheet aluminum, and it's more comfortable to be in a boat like this, especially when you're on long walks, and in the rain, the drops don't thunder down the bottom, making a deafening noise, but they rustle quietly across the surface, which is highly valued by anglers who are careful to fish.
Disadvantages and limitations of the material
Despite the impressive list of advantages, PHD boats have their drawbacks, which you need to know about before buying. The main one is weight. Plastic boats are usually heavier than their aluminum counterparts comparable in size. Wall thickness should be sufficient to ensure rigidity, which leads to an increase in mass. For a single fisherman who is used to dragging a lightweight Kazanka or inflatable, this can be an unpleasant surprise.
The second big downside is the fear of high temperatures and open fire, which is hard to ignite, but it's combustible. In a fire, an HDPE boat will burn completely, turning into a sticky mass, whereas aluminum will simply melt at much higher temperatures and fiberglass will charred, so smoking in such a boat requires increased caution, and storage near fire sources is strictly prohibited.
The third thing is that the memory of the deformities is incorrectly operated, and although the HDPE is elastic, if you leave the boat in direct sunlight in extreme heat (over 50-60 degrees) in a loaded state (for example, on skewed slips), it can swim and change the geometry, and once it cools, it will remain skewed, which requires careful consideration of storage conditions in the summer.
⚠️ Warning: Do not leave the boat from the HDPE in the sun with the hatches closed. Inside, you can create a greenhouse effect, pressure will increase, and the sides may inflate, which will lead to irreversible deformation of the structure.
Also worth mentioning is the complexity of painting. If you're tired of the color of the hull, you can't just paint the boat with ordinary paint, because polyethylene has very low adhesion. You need special soils or spraying technologies to change the color or apply logos, which is almost impossible to do at home.
Comparison: HDPT vs. PVC and Aluminum
To make a final decision, let's compare three basic materials: aluminum is valued for its lightness and stiffness, PVC for its portability and compactness, and HDPE for its "unkillability" and durability niche. Each material dictates its own game, and the choice depends on the use cases.
If we consider longevityPVC is better than PVC for puncture resistance and abrasion, but it loses to aluminum in heat resistance. PVC is closer to fiberglass in terms of comfort, it is warm to the touch and quiet. Aluminum cools in winter and heats in summer, transferring temperature to the inside of the cockpit. PVC is neutral in this regard, but depends on air temperature.
Transportability is a weak point of the HDPE. The boat can't be folded into the trunk like an inflatable one, and it requires a trailer or a permanent place on the water. Aluminum is more flexible in this regard, many models are disassembled or have a flat bottom for transportation on the roof of the car. However, if you have a constant descent to the water or a trailer, the question of dimensions disappears.
Below is a table that systematizes the basic parameters for quick comparison:
| Parameter | A boat from the MHP | aluminum boat | PVC boat |
|---|---|---|---|
| Weight (by 1 m of length) | Tall (25-35 kg) | Medium (15-20 kg) | Low (10-15 kg) |
| Resistance to puncture | Very high. | High (but possible dents) | Medium (depending on density) |
| Repairability | Tall (cooking) | Medium (argon welding) | High (glue/patch) |
| Term of service | 20+ years | 30 years. | 10-15 years |
| Price. | Medium/High | High. | Low/Mediocre |
Repair and maintenance of the hull
One of the great things about plastic boats is that they can be easily repaired in the field, and if aluminum needs argon welding and oxide film stripping, and PVC needs degreasing and waiting for the glue to dry, then HDPE can be repaired by simple soldering, and you just need a conventional dryer and a rod of the same polyethylene.
The process of retightening is as follows: First, the edges of the crack or the hole are cut to allow the melted material to enter, then the hairdryer warms up the repair area and the filler rod. When the material becomes visco-fluid, it simply rubs or melts into the damage, and then cools down, it forms a monolithic seam that is as strong as the main material.
☑️ Tools for emergency repair of HDPE
It's important to use a rod of the same type of polyethylene that the boat is made of. Although visually they may be similar, different grades of HDPE may have different melting points. If you use an incompatible material, the seam can detach under load. Usually, manufacturers put a small piece of remix as a baseline.
⚠️ Warning: When using an open flame (gas burner) for repair, be extremely careful. Plastic is easily ignited when overheated. It is better to use a hair dryer or special nozzles on the burner that direct hot air, not fire.
Winter Operation and Storage
The unique thing about low-pressure polyethylene is that it doesn't lose its mechanical properties in cold temperatures. While PVC becomes oak in the cold and risks cracking when bending, and some plastics become brittle, the PHP remains elastic, making it ideal for winter fishing, when you have to punch holes right next to the side or pull a vessel out on ice.
However, keeping such a boat requires certain rules. Despite its frost resistance, the material is sensitive to ultraviolet light. Prolonged storage in direct sunlight (especially in summer) can lead to color burnout and gradual aging of the surface layer. It is recommended to cover the boat with an awning or store it indoors, garage or under a canopy.
In winter, you can keep the boat outdoors, even under snow, and snowdrifts are even useful, they protect the hull from direct sunlight, and the main thing is (make sure) that there is no water left inside the boat, which, when frozen, can expand. Although the HDPE is elastic and often withstands the expansion of ice without breaking (unlike hard fiberglass), it is better not to test fate and turn the boat over or leave the exhaust holes open.
HDPE boats are one of the few that can be safely operated all year round, including winter fishing, without the risk of material destruction in the cold.
FAQ: Frequently asked questions
Can I cook a boat from the PND with a conventional soldering iron?
A conventional electric soldering iron for minor electronic repairs is not suitable, since it has too small a sting area and low power to warm the thick walls of the boat. However, you can use a powerful soldering iron for plastic pipes or a special thermoknife.
Does the bottom of such a boat scratch against the rocks?
Yes, scratches are inevitable in active use. However, unlike aluminum boats, where a deep scratch is a potential hole, on HDPE, scratches only remain on the surface. The material has the property of self-healing minor damage, and scratches do not affect the tightness and strength of the hull for years.
Do I need to paint the boat from the inside?
There's no need. It doesn't absorb water, it doesn't rot, it doesn't rust, it doesn't hold the paint well without any special preparation. Inside, the boat usually has a corrugated surface (anti-slip bottom), which is very practical. The only thing that you might need is a cleansing with dirt detergents and fish slime.
What is the maximum size that can be made from PHD?
Rotary molding technology allows boats up to 6-7 meters in length. However, due to the weight of the material, boats larger than 5 meters become too heavy to carry on a light trailer without a powerful tractor. The optimal size for HDPE is 3.5-4.5 meters, which is ideal for fishing and recreation on small bodies of water.
Does the color of the boat fade over time?
High-quality shipbuilding polyethylene contains UV stabilizers that slow fading. However, after 5-7 years of active use in the sun, the color may become slightly paler (surface shining effect). This is an exclusively cosmetic defect that does not affect strength. You can use plastic polishes to return the rich color.