| Composite kayak materials...the Rosco difference |
A top quality canoe or kayak can only come from a top quality mold, and at Rosco Canoes, we pride ourselves on our ability to produce and maintain excellent quality molds.
Rosco Canoes generally opts for stronger lay-ups than the norm, while maintaining comparable weight. Like the overall care and quality we put into our products, it's another measure of the craftsmanship that distinguishes Rosco Canoes and kayaks. Please keep in mind if you have any special requirement regarding strength or weight reduction as we are happy to accomodate.
The production process begins by spraying gelcoat into a highly polished mold, (separate molds for the hull and deck). After curing the gelcoat, resins and cloth layers are meticulously hand-laid into the mold. After a curing period, the mold is opened. The hull and deck are removed, inspected, some initial outfitting is completed, the components are carefully alligned joined and sealed, the craft is then ready for trimming.
Choosing a Rosco Kayak ensures you are selecting the finest materials and moulds in which to craft your kayak. Ross alone has over 40 years of professional canoe and kayak manufacturing experience, and yes it's true - he did manufacture his first wooden canoe at age 10.
... the slogan still stands "simply the best".
| Fibreglass kayak material (FG) |
Kayak production in fibre-reinforced plastic dates back to the 1950s. The material provides the ability to produce very fine lines, literally down to a knife-sharp entry if desired.
Fibreglass forms a lighter kayak than polyethylene (plastic). Additionally, greater stiffness and a very smooth finish enhance the glide of fibreglass kayaks. The cloth used in the construction of a fibreglass kayak is carefully selected and positioned in relation to the mechanical role it will play, resulting in a stronger craft.
Fiberglass Advantages:
• Extremely lightweight
• High strength-to-weight ratio
• Can be formed to very fine design lines
• Moderate cost
All of our fiberglass models have different lay-ups to suit their design and/or intended use.
We only use the highest grade materials in our manufactoring process. Each Kayak incorporates a knitted double-bias fibreglass fabric, core mat and C.S.M. with selected reinforcement in key areas to produce the finest quality kayaks in Australia.
| Kevlar kayak material (K) |
Kevlar® offers an excellent compromise for paddlers seeking lightness and performance. Kevlar® is stronger than carbon, but lighter than fibreglass. Kevlar® is five times stronger than steel on an equal weight basis, yet at the same time, is lightweight, flexible and comfortable. It is this unique combination of attributes which enable kayak manufacturers (who are knowledgable in its unique characteristics) to produce a product that are lighter weight and stronger than traditional glass fibre models. Although Kevlar is more expensive than glass fibre the benefits are apparent, making it well worth the investment.
General Features of KEVLAR® :
- High Tensile Strength at Low Weight
- Low Elongation to Break High Modulus (Structural Rigidity)
- Low Electrical Conductivity
- High Chemical Resistance
- Low Thermal Shrinkage
- High Toughness (Work-To-Break)
- Excellent Dimensional Stability
- High Cut Resistance
- Flame Resistant, Self-Extinguishing
How is a Kevlar boat different from a fibreglass boat?
Kevlar kayaks are made using a sandwich of fibreglass and Kevlar fabrics bonded together with vinylester resin. There is almost always a fibreglass cloth of some type as the outside layer(s). Because Kevlar is much higher in stiffness and tensile strength than fibreglass, the builder can use fewer layers of cloth and in turn use much less resin reducing weight by approximately 15-20%. Kevlar is much more expensive than fibreglass and much more difficult to repair. It can be easily recognized by its gold colour.
Will the Kevlar boat be faster than the fibreglass boat?
Not enough to be very noticeable. Unless you are an avid racer, the best reason to buy a Kevlar kayak is the advantage of lighter weight when loading and unloading onto your car and carrying the kayak to the beach. If these reasons are not an issue, save yourself a bundle and get a fibreglass kayak. You can get some really nice accessories with your savings!
Will a Kevlar boat be stronger than a fibreglass boat?
The short answer is no! This is in part because they use substantially less material in the Kevlar kayak to reduce the weight. However a Kevlar kayak built with the same lay thickness as a fibreglass kayak will be substainitally stronger pound for pound. Kevlar is very high in tensile strength but relatively low in compressive strength. An all-Kevlar boat would show initial damage fairly easily from a hard blow. The damaged cloth might stay together even though much of the resin around it will have fractured. If you expect to use your kayak in the surf zone or around rocks, Kevlar is not a good material choice.
| Carbon kayak material (C) |
Carbon fibre offers the maximum weight reduction of all composite materials whilst maintaing the rigidity and strength required in most kayaking applications, carbon is not suited to all applications and suits a lightweight racing layup most effectively. Carbon is quite expensive yet if weight and performance is the issue then carbon is the choice for you.
How is a carbon fibre kayak different from a fibreglass or Kevlar boat?
There are a few manufacturers building "carbon fibre" kayaks. You can tell the carbon fibre by the jet black colour resulting from the process used to make the cloth. They are almost always left visible by using a clear resin to the outside so as to display the high-tech fabric. Carbon cloth is very stiff (stiffer than Kevlar) but lower in tensile and compressive strength. The advantage to carbon is the chance to use even less material than a Kevlar boat resulting in even less weight. These boats tend to be very costly and somewhat brittle.
| Carbon/Kevlar kayak material (C/K) |
Carbon-Kevlar® kayaks are constructed for high-performance, combining the extreme lightness of carbon and the elasticity of Kevlar®.
What are the characteristics of a carbon/Kevlar kayak?
Many of the manufacturers producing kayaks using carbon and kevlar woven together. As you can guess the fabric takes advantage of properties from both materials creating a lighter weight kayak that is quite stiff although surprisingly not quite as strong as the same kayak in a fibreglass lay-up.
| Maximising kayak hull rigidity |
Core materials are carefully positioned in all composite kayaks to optimize their strength. These materials such as core mat and C.S.M. increase kayak thickness in locations most subject to stress, such as bow and stern toggles, hatch rims and the area immediately fore and aft of the cockpit. To obtain a good ratio between weight and sturdiness, a balance must be achieved between the use of core materials and fibre cloth.
| Quality vinylester resins |
The vinylester resin (modified epoxy) used in the production of all composite kayaks is similar to the epoxy resins used in the aerospace industry. Besides having better mechanical properties when compared to polyester resins, its elasticity is about three times greater. Moreover, vinylester resin is easier to repair.
| Which kayak material will suit my needs? |
The difference between polyethylene (plastic), fibreglass, Kevlar® and carbon kayaks?
Polyethylene (plastic) kayaks are shock-resistant, low maintenance and affordable kayak. However, they can be deformed if they are not stored properly and they are heavier than composite kayaks.
- Composite kayaks can be made of fibreglass, Kevlar® or carbon.
- Fibreglass produces a lighter kayak than polyethylene (plastic). Additionally, greater stiffness and a very smooth finish enhance the glide of fibreglass kayaks.
- Kevlar® offers an excellent compromise for paddlers seeking lightness and performance. Kevlar® is stronger than carbon, but lighter than fibreglass.
- Carbon-Kevlar® kayaks are constructed for high-performance, combining the extreme lightness of carbon and the elasticity of Kevlar®.
Composite is a confusing all inclusive term used to describe kayaks made of fibreglass, Kevlar or carbon... or any combination of the above materials. Composite kayaks are made by hand fitting layers of cloth into a gel-coated mold and then adding resin to create a stiff, tough shell using a number of processes from hand lay-ups, to high tech vacuum bagging & infusion lay-ups. The outside gel-coat adds additional protection, produces an attractive, shiny finish but most importantly enables the kayak to be relieved from the mold. Contrary to common belief fibreglass kayaks are tough and average 20% lighter than similar Polyethylene kayaks. Kevlar kayaks weigh 10% less again, yet offer the additional impact strength of Kevlar. Carbon offers slightly lighter craft weights again. However, these kayaks must be handled with care.
You will only really know why you should buy a composite sea kayak once you own one! Composite kayaks are high performance, quality craft, custom built just for you. Once you have used one it's going to be hard to settle for anything less. Part of the attraction of owning a composite kayak is that you enter a select world of people who want the very best and are happy to spend that little more time looking after it, keeping it at its best and you will forever enjoy the superb feeling of gliding effortlessly through the water. The efficient grace, smooth lines, beautiful handling and amazing appearance of a well-built composite sea kayak really are something to behold.
There are practical reasons too, like being lighter and more rigid. This gives better efficiency through the water and the ability to customise your kayak with the many different specification options and colour choicesof your deck, hull and trim.
The satisfaction you will get out of a composite kayak is not in a graph or table nor is it valued in monetary terms either, it will be in your own satisfaction of owning something very special that you will enjoy on your adventures long or short, serious and committing, or perhaps more relaxing and peaceful for many years.
| why are composite kayaks so expensive? |
The short answer is that they are a lot of work to build. The slightly longer answer is that if you want a high quality, state-of-the-art touring kayak that is lightweight and lasts there are no shortcuts to get this result. We could build our kayaks in a few hours less per kayak but quality would suffer. This difference in build quality would not be readily apparent at first but would show up as the kayak gets older. Using somewhat cheaper materials is a temptation but results is a lower quality kayak. Doing this is a relatively small saving compared to the final cost and not worthy of consideration.
| are all kevlar kayaks created equal? |
No. Some of our competitors are building Kevlar kayaks with a minimum of Kevlar in them, expecting that the customer ... thats you, wont notice!! Some kayaks have as little as one layer in the hull only and are sold as Kevlar kayaks.
We build our Kevlar boats with a maximium Kevlar in them. We are the only kayak builder who uses a glass/Kevlar hybrid first layer. This layer has the glass fibres on one side and the kevlar fibres on the other. There is a polyester thread woven around these fibres to hold the cloth together. The fibres themselves are not bent or crimped from being woven which slightly improves their strength properties. We orient this material in the most appropriate directions to achieve maximum stiffness. The glass fibres are on the outside of the laminate.
Kevlar kayaks should always have a layer of glass fibre on the outside of the laminate as Kevlar is not very good under compression. Kayaks built with only Kevlar will suffer compression damage on the outside of the laminate and will eventually become damaged, and so we reinforce our Kevlar decks with uni-directionl glass and the hulls with uni-directional glass and a core utilising a twill weave Kevlar to acheive the maximum multi-directional strength and of course the strongest possible lay-up available.
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