The majority of plastic kayaks on the market are Polyethylene. Plastics, food packaging, cosmetics, pharmaceuticals, industrial processes, biodegradable plastics, and medical devices commonly use this polymer form. It is less expensive and more plentiful than other materials.
Manufacturers offer a variety of materials and proprietary high-tech processes for producing a particular model, ranging from recreational boats to elegant racing boats, bulletproof centerboards, and other sport boats.
To begin this process, you must ascertain the type of use and abuse that the kayak will be subjected to. This is critical in determining the best material to use in a particular body of water.
The following is a brief overview of the various plastic materials and construction methods, along with their associated benefits and drawbacks.
Mostly hand-stitched and glued-together boats, or striped construction boats. The possibilities for creating striped boats are nearly endless, and thanks to sewing/gluing kits, you don’t need to be an advanced carpenter to do so. You can even hire someone to complete the task on your behalf.
Here’s a more complete guide to the plastics used in making kayaks:
Although rotationally molded kayaks are made primarily of a single type of “polyethylene” (PE), this plastic comes in a variety of varieties. These grades are designated as HDPE (high density), MDPE (medium density), and LDPE (low density) – the term “density” refers to the number of molecular bonds in the plastic, not its weight. The more molecular bonds in a plastic, the stronger it is, the harder it is, the more puncture and abrasion resistant it is, and the more memory it has.
Memory refers to a plastic’s ability to retain its original shape, thereby extending the product’s life. Complex plastics, such as HDPE, have superior chemical properties and quality control due to their use of UV stabilizers and plasticizers that meet stricter standards.
HDPE is more expensive to purchase and more susceptible to mold than HDPE or LDPE.
MDPE is more expensive to purchase and has a higher mold resistance rating than LDPE.
LDPE polyethylene is the least expensive to purchase and mold.
linear high density polyethylene HDPE:
PE is used on kayaks that are used in extreme conditions such as whitewater sports, sea kayaking, and deep sea fishing.
HDPE is more expensive and labor intensive to mold, but it has the highest strength and durability. HDPE kayaks are molded at higher temperatures, whereas LDPE kayaks are more resistant to warping when installed or stored on a trunk.
When it comes to creating stronger kayaks, HDPE manufacturers must make a trade-off between durability and aesthetics. Because HDPE stretches easily, it has a more smooth appearance than HDPE, which retains its shape and is not as smooth.
linear medium density polyethylene HDPE:
is PE for kayaks used by ordinary people, not those used to paddling in 60-foot waterfalls or in polar regions.
linear low density polyethylene LDPE:
Commercial kayak manufacturers in China prefer LDPE due to the product’s price point. Commercial kayak manufacturers use LDPE, emulating foreign designs and manufacturing kayaks under environmental and operating conditions that we believe are unacceptable in the UK – but the kayaks produced meet the required price point.
The simplest of the three plastics used to construct kayaks is LDPE or LLDPE. It is the least expensive material and can be molded at lower temperatures, but has significantly less strength, impact and abrasion resistance, UV resistance, and storage capacity than MDPE and HDPE.
The Canoe Shop group wishes for everyone to be able to afford paddling, but is forthright in its assessment. It took us more than five years to develop a line of affordable HDPE kayaks for retail sale. In many ways, China continues to produce a great deal of junk, so buyer beware!” We were able to offer Fun Kayaks made of LDPE for sale in the UK once we were convinced that they were a good product.
Our other customer guarantee is that we will replace a defective Fun Kayak with a comparable product, but we will not replace other LDPE kayaks with defective ones.
For the technically savvy, there is a top-quality kayak mold manufacturer in the United Kingdom.
Choosing the appropriate material for kayak construction is a critical decision for any kayak manufacturer.
Plastics come in a variety of shapes and sizes, but because the majority of kayaks are manufactured via rotational molding, polyethylene proved to be the most suitable material.
Regrettably, many common types of polyethylene are not suitable for kayak construction. They are classified as LDPE (low density polyethylene; density ranges from 0.910 to 0.925 g/cm3) and LLDPE (linear low density polyethylene; density ranges from 0.910 to 0.940 g/cm3) and were originally used to manufacture water tanks, waste containers, toys, and furniture. They are brittle due to oxidation, have a low tensile strength, are prone to bending, particularly in flat areas, are prone to warping, and are susceptible to damage from UV radiation if not stabilized with UV treatment.
HDPE (high-density polyethylene; density of at least 0.941 g/cm3) is a more suitable material for kayak construction. It has a higher tensile strength and is stiffer than LDPE and LLDPE, which provides stiffness, scratch resistance, and impact resistance to the boat.
Palm utilizes a material called HDPE ultra-linear polyethylene (density 0.949 g/cm3), which was developed specifically for the UK kayak industry years ago by Matrix Polymers. It has the same properties as HDPE, but the polymer forms more linear chains, resulting in a crystalline structure and increased strength and durability for use in harsh kayaking environments.” Without using the “forked marketer’s language,” the director of Dagger & Wilderness Systems Kayak UK describes the situation on behalf of a group of canoe retailers.
How polyethylene kayaks are made.
The 1970s saw the introduction of rotationally molded polyethylene kayaks. Plastic pellets were cast into a hollow metal mold, which was then heated and rotated in a massive furnace to distribute the melted plastic throughout the mold.
Once cooled, the mold was removed and the perfect kayak was created, requiring only minor adjustments to the cockpit, hatch, and rudder installation, and ready to launch.
Polyethylene is a strong plastic that is used to create a variety of products ranging from boat hulls to food containers to traffic cones. As implied by this list, it is extremely durable, and so-called “Tupperware kayaks” can last for many years with little maintenance.
If your kayak needs to be waterproof against pebbles, towable on the beach, or transported on a roof or trailer, polyethylene may be the best choice. Additionally, it is the least expensive choice.
Simply because plastic can withstand a bump does not negate the need to compensate. Collisions with rocks and crustaceans can result in the formation of a curly, fuzzy tail, which increases durability. Additionally, polyethylene is significantly more dense than other hard shell materials.
When ultraviolet light strikes polyethylene, it degrades. As a result, you should spray 303 Protectant or another similar UV protection spray on your plastic kayak.
On warm days, old, sun-damaged plastic covers (or new plastic covers that are too tightly attached to the roof rack) can develop faint grooves called oil canisters.
The cheapest and most commonly used type of kayak is plastic. Plastic pellets are poured into a mold in a factory and then heated and rotated in a process called rotomolding. The plastic material conforms to the shape of the mold’s interior. This procedure is complicated by the fact that cooling the plastic shrinks it, and improper technique can result in twisting and warping. However, it is a cost-effective method of producing kayaks for recreational use in large quantities.
While polyethylene is a strong material, it is also quite heavy, limiting the boat’s performance. The plastic has a long lifespan due to the UV inhibitors contained within it. Generally, seats are not adjustable and are molded into the hull. This adaptable design compromises crew comfort and frequently restricts use to small cruisers.
The material used to construct a canoe has a significant impact on its intended use, durability, and cost.
Each of the following canoe materials has advantages and disadvantages:
Canoes marketed as “plastic” are actually composed of a variety of materials and manufacturing processes. Plastic canoes are manufactured in two basic ways.
1 – Thermoforming
Thermoformed canoes are constructed by laminating polyethylene, high-strength ABS, and/or acrylic together to create an extremely hard and UV-resistant outer surface.
Thermoformed canoes are ideal for recreational, touring, and family use. Their advantages include their light weight, low cost, and durability, all of which contribute to their increased performance.
The disadvantages of thermoformed canoes include their shorter life expectancy in comparison to fiberglass canoes and their inability to handle heavy-duty paddling.
2 – Rotational molding/polyethylene
Canoes that are rotationally molded are constructed by rotating solid blocks of plastic that are then cut and “molded” into the canoe mold.
The advantage of these canoes is their low cost of manufacture, high durability, and low maintenance requirements. They make excellent recreational canoes, rentals, outfitters, and family canoes because they can be declared as good as any other canoe.
One disadvantage of rotationally molded canoes is their heaviness.
Optimal Application. Outdoor activities, recreation, and rentals
Old Town Canoes Materials
By sandwiching polyethylene foam between two layers of thin, rigid polyethylene, Old Town Canoes pioneered the use of triple-layered polyethylene. This adds buoyancy and strength to the material.
Today, a number of manufacturers offer three-layer plastic shelled canoes. The City of Old Town utilized the following materials.
Materials for inflatable canoes
Inflatable canoes of the modern era are constructed from a variety of tough materials. Unlike the inflatable boats with which you grew up, modern inflatable canoes will not crack or leak the first time they come into contact with a rock.
Modern inflatable canoes are constructed from tough vinyl, PVC, and ripstop nylon.
Optimal Application. Inflatables are an excellent choice if you have limited space and/or a small vehicle for transporting your canoe back and forth. Additionally, some high-quality inflatable canoes are ideal for river adventures and whitewater.
Best Materials for Canoes
The best materials for canoes are those that are compatible with your paddling style and the body of water on which you intend to paddle.
Aluminum and hard plastic – for rocky beaches and rough waters
Water that is calm and smooth – almost any type of plastic, aluminum, or wood is appropriate.
Canoes made of fiberglass, lightweight plastic, or kevlar are ideal for rapid paddling.
Kevlar or other lightweight composites are ideal for frequent transitions.
Use rotationally molded polystyrene canoes for family camps, summer camps, and equipment rentals. These canoes can withstand heavy loads while still paddling.
Rotationally molded and thermoformed plastic canoes are the best option for inexpensive canoes, especially for beginners.
How it’s made: polyethylene and molding.
Polyethylene is consumed at a rate of about 80 million tons per year. It is the most prevalent type of plastic, with everything from plastic bags to kayaks being made of it. Additionally, this material is extremely strong, making it ideal for kayaks.
There are several methods for polyethylene modification, the majority of which involve the use of molds to shape the boat.
Rotomolding produces a seamless kayak that is typically more expensive but more durable. In an oven, a large mold is filled with plastic powder. The powdered plastic becomes a liquid when heated in the oven. The finished product is then cooled to create a seamless kayak.
These seamless kayaks have a more rounded shape than two-piece kayaks constructed using comparable molds. Typically, these individual pieces are attached using a material such as the aforementioned water-resistant glue, which seals and waterproofs the boat.
Continuous rotation of the molds used to create the kayaks ensures uniform thickness. This ensures a smooth and even finish on the completed kayak. This is an enthralling procedure.
Polyethylene is a petroleum derivative discovered by the German chemist Hans von Pechmann in the late nineteenth century while heating diazomethane, another chemical he discovered. The resulting waxy white substance was named “polyethylene” due to its presence of long -CH2 chains. In 1933, the first industrially viable synthesis of polyethylene was performed, once again by accident, by a group of specialists in England.
They used extreme pressure to create a waxy white substance from a mixture of ethylene and benzaldehyde. They encountered difficulties reproducing the substance, however, because they were unaware that the initial experiments had been contaminated by oxygen. Two years later, another chemist replicated this “accident,” and the material was industrially used in 1939.
World War II resulted in the cessation of production of a large number of materials, including those used to construct these kayaks. However, as plastic became more accessible and was incorporated into a variety of products, it became more widely used. Plastic makes them more durable, and if you’ve ever spent a day on the lake with the water level low enough, you’re well aware that your kayak will suffer from bumps and scratches from time to time.
Whichever style you choose, your kayak will last a long time if properly maintained.
How to repair damage to plastic kayaks and canoes
Lyra is a scratch, hole, dent, and crack repair product
Numerous plastic canoes and kayaks are constructed using a material called high-density polyethylene (HDPE), which is notoriously difficult to repair. Chemical properties that contribute to your boat’s flexibility and strength also prevent it from bonding with other materials.
HDPE is generally impervious to repair with conventional adhesives and sealants in the majority of applications. This is not to say that scratches, dents, holes, or cracks in a plastic kayak should be ignored. A how-to manual for repairing all types of damage that may occur to your vessel during its lifetime.
Buying a sea kayak – pros and cons of plastic boats
Sea Kayaks Made of Plastic – How to Store Them The process of purchasing a sea kayak can be complicated. We are frequently asked about the materials used to construct sea kayaks, and many people gravitate toward plastic boats due to their low cost and reputation for ease of maintenance. While the first point is valid, an attitude of “don’t touch” toward plastic kayaks can result in future problems!
Thus, let us first define a “plastic” kayak. They are constructed of polyethylene plastic that has been thermoformed in a variety of ways to form a single unit with only the hatch and cockpit holes cut out and the equipment (seats, decks and risers, bungee cords, etc.) attached. In comparison, boats constructed of composite materials (fiberglass and other materials) have a separate deck and hull that are then attached. Composite materials are more costly and labor intensive to manufacture. As a result, the cost of the boats produced increases.
The advantage of plastic kayaks is their durability, particularly when dropped or struck while paddling; as previously stated, this construction results in the lowest prices for new and used boats. However, as will be demonstrated below, the concept of “indifference” has limitations.
Plastic has a number of disadvantages compared to other materials. The first consideration is weight: plastic kayaks are substantial in weight. A full-size plastic sea kayak 16-17 feet in length weighs 60-70 pounds or more, whereas a composite kayak can weigh as little as 20% to 25% less. When the boat travels over rough terrain, “hairy” dents form on the hull, slowing the boat’s progress through the water. In rough water, some people notice that plastic boats sag significantly more than composite kayaks, resulting in poor handling; however, few people notice the difference in calm water.
It is necessary to store polyethylene indoors or under cover, as UV rays can degrade the material. It is recommended to spray with 303 on a regular basis. When shelves (or straps) are used to store items, the supports must align with the interior partitions! Failure to comply with this requirement will result in boat damage.
If this is not done, the boat may warp or become “crowded.” Occasionally, oilers can be repaired, but this is a difficult task that should not be undertaken lightly. Snugly strapping a plastic boat to a roof rack on a hot day can result in the same damage or even transform your prized kayak into a vibrant banana.
After paddling in salt water, all kayaks and gear should be thoroughly rinsed (inside and out). This point is critical. As a result, plastics do not outperform other materials in this regard. Due to the fact that salt is corrosive and abrasive, it should be removed immediately.
As illustrated in the attached photo, the support corresponds (or nearly corresponds) to the bulkhead’s position. Additionally, laying on the boat’s side helps maintain its shape.