Canoe durability | what is the best boat building material?

As a Saskatoon paddle shop we get asked a lot of questions about canoes. One of the most common ones is how durable they are. Is aluminum stronger than fiberglass? Can you take a kevlar boat down rapids? 

Most importantly, think of how you want to use your canoe. If you expect to be hitting rocks or dragging the boat up on gravel shores then overall durability may be your primary concern. If you want a boat that is efficient to paddle, or need something lighter to get on your vehicle or over the portage, you'll be looking at a strength-to-weight ratio that suits your needs better.

There are a lot of factors that determine how durable a canoe will be. It is commonly thought that aluminum and Royalex-type plastic laminate boats are the toughest but there are pros and cons to each hull material and layup. We explore some of the common ones below. 

Aluminum Canoes

Aluminum canoes were the first new thing after wood and wood/canvas canoes. Affordable and practically indestructible they became the go-to for rental and school programs, wilderness trippers and families. Many of us remember the old Grumman canoes: noisy, cold (or burning hot) and crushingly heavy. Aluminum is no longer sought after although due to their longevity you still see fleets of them around. If you manage to rip one you can weld it together but the dents and scars won't disappear.

Pros of aluminum hulls: can last indefinitely, not affected by UV, take a lot of abuse

Cons of aluminum hulls: cold (or hot), heavy, noisy, not nice lines, sticks to rocks, will dent and not go back into shape

Plastic Canoes

There are two main families of plastic canoes: polyethylene, and what's commonly known as Royalex. Royalex was a popular canoe building material that is no longer available; however T-Formex has replaced Royalex and is almost the same material.

Polyethylene (PE) canoes have a wide range of properties depending on what type of PE is used and how it is constructed. Generally considered the toughest material out there, PE canoes are usually very durable, overall quite heavy, and are UV sensitive to degredation. The low priced canoes you find in big box stores are often made of thermoformed PE or single layer PE. These boats, while tough, will fade, lose their shape, and have a short lifespan. Because the material is so soft these canoes need additional stiffening; often these canoes have a metal rod running down the keel line which adds even more weight to an already heavy boat.

Densities of PE includes linear low density (LLDPE), medium density (MDPE) and high density (HDPE). LLDPE is the least expensive to manufacture and is made by pouring plastic powder or pellets into a mold and then heating and rotating it. The result is an inexpensive, extremely heavy plastic boat with excellent impact resistance.  HDPE canoes are the lightest and stiffest boats (easier and more efficient to paddle) with almost the same level of durability as LLDPE.

The number of material layers (and thickness) is another important factor. A single layer boat made of a thick layer of PE will be the most sturdy and the softest. Often whitewater kayaks are made in this way as they absorb impact very well. This softness however makes them slower and less efficient to paddle. Three layer PE canoes are made of a material with PE outer layers and a closed cell foam layer sandwiched in the middle. This construction generally results in a stiffer, lighter boat with good durability and the added bonus of inherent flotation. 

T-Formex boats are made of laminate sheets. The sheets have outside layers and a closed-cell foam inside layer that adds buoyancy and stiffness to the boat. T-Formex has the durable properties of plastics but makes a lighter boat than aluminum or poly. They are extremely popular for wilderness tripping, whitewater and recreation.

Unlike aluminum boats that stick to rocks, plastic boats will slide over them. They also "bounce" off rocks (depending on how you hit them). They are more susceptible to UV degredation however so it's best to store them out of the sun. If plastic boats heat up in the sun they grow softer and can deform; we've seen boats with grooves in them made by the straps holding them on to a roof rack. Generally if you warm them up again they will go back into their original shape. This inherent softness of the material can also cause these boats to "oil can", an annoying flexing of the hull as you paddle.

PE boats are difficult to repair as almost nothing sticks to the material. T-Formex is more forgiving as far as repairs go, but is not as straightforward as repairing a composite boat.

Pros of plastic hulls: very durable, slides over rocks

Cons of plastic hulls: abrades over time (hull becomes "fuzzy" which slows the boat down), heavy, blunt exit and entry lines, less stiff, can be more difficult to repair

Composite Canoes 

This is a huge family of canoes and includes any that are made with a cloth and resin layup. The cloth can be fiberglass, aramid (kevlar), graphite, or combinations of weaves. The type of resin used has a huge impact on how durable and long-lasting the canoe will be.

These canoes are typically built by layering the cloth in a mold, applying resin and then vacuum bagging to extract the most amount of resin, resulting in stiff light boats. This construction method allows for sharp entry and exit lines and the best ability to create performance hull shapes. 

Flotation is often added in the form of float tanks. The hulls are stiffened in a variety of ways including foam cores, ribs, or multiple layers of fabric. Generally the strongest boats will be made of lots of layers of fabric and they'll be the heaviest. Boats with ribs will be lighter but the ribs create non-flex points that concentrate stress upon impact. Foam cores will disperse impact force better.

Cloth properties vary. Fiberglass is the most affordable and can be extremely strong with a mulit-layer layup. Aramid, a cloth used in the aerospace industry and in manufacturing bulletproof body armour, will give you a lighter, stiffer boat but it will be more expensive as the fabric is more difficult to work with. Carbon cloth makes the stiffest, lightest hulls that can be almost as strong as kevlar. Carbon boats (also known as graphite) are often made with kevlar layers. 

Resins are typically polyester, vinylester, or epoxy. When buying a canoe make sure you ask what type of resin the hull is made of as it directly relates to the durability and lifespan of the boat.

Polyester resin is the least expensive and creates a brittle boat; it is commonly used for inexpensive fiberglass canoes. There are higher quality polyester resins (such as isophthalic resin) that are more UV and chemical resistant, thermally stable, and have higher tensile strength.

Vinylester is considered a combination of polyester and epoxy resins. It flexes better than polyester, has a longer lifespan and resistance properties, and is a good compromise of strength and price. 

Epoxy resin is the most expensive and the highest quality resin you can get, resulting in the strongest hulls. It is more difficult and slower to work with and  requires heat to cure, so many boat builders shy away from this. Boats built with epoxy resin have the highest strength-to-weight ratio.

Layups affect the durability of the canoe. The canoe you see below is an ultralight layup. This means there is no gel coat on the outside of the hull so it is the honey colour of the aramid cloth. Gel coats come in lots of colours and although they add weight to the boat they are the first defense against UV and scratches. Ultralight boats, because they lack this defense, are often reinforced with outer S-glass layers and epoxy resins for durability. Although you should keep all canoes out of UV exposure as best you can (it is the number one degrader of boats) it is especially important with ultralight models.

It should be noted that there is a lot of variation in durability within a layup type. For example an Ultralight layup (kevlar, no gel coat) can be quite fragile or quite strong depending on how the boat is stiffened, how the material is laid down, and what type of resin is used. We sell Ultralight boats that are a joy to portage but would crush if they hit a rock; we also sell Ultralight boats that can take quite a beating scraping over rocks.

If you are running rivers and rapids and expect some impacts, don't immediately discount a composite canoe. Due to their responsiveness they are easier to steer so you can avoid a lot of potential impacts. Some layups are designed to absorb impact better by allowing the hull to flex slightly. This is done by hanging seats rather than riveting them in (reduces non-flex points) and using multiple layers of fabrics in stress areas, along with more flexible resins. Sometimes other types of fabrics are also used in the layup to add even more resiliency. It has been said that a strong multi-layer composite canoe is as strong as Royalex with a better strength-to-weight ratio.

Pros of composite hulls: best strength-to-weight ratio, easily repaired, efficient hull shapes, responsive and stiff, lots of colour options

Cons of composite hulls: depending on layup can be less durable against sharp impacts than plastic or aluminum

So which kind of canoe should I get?

It can be overwhelming comparing building materials and manufacturing processes to come up with the perfect boat for you. First of all, choose a reputable paddle shop so you get the best advice you can. Know what kind of paddling you will be doing and on what kind of water, and be honest about your paddling ability. Have a priority list in mind to help narrow down the possibilities. How important is weight to you? Is your budget limited or can you be flexible about price? Will you be lending your boat to others that may drag it up on the shore? The more you think about these things the better equipped you will be to find your perfect canoe.