Part 2: Rowing Shell Materials
When you’re buying a new or used racing shell, there’s a lot of technical jargon thrown around that probably isn’t part of your every day vocabulary. We have a three-part series that takes a stab at defining the terms that you may hear or read from a boat manufacturer, and how they affect your rowing shell’s performance and longevity. Did we miss one? Let us know.
Carbon Fiber: A fabric made up of extremely thin carbon atom fibers. Carbon fiber gets its strength from the way the atoms bond with microscopic crystals and align themselves along the long axis of the fiber, which by its nature provides a very strong bond. Strands are woven together to form yarn, which is then woven into fabric. The fabric is available in many different styles depending on the intended use.
Fiberglass: A fabric made up of very fine strands of glass. The first composite boats were made entirely of fiberglass, though it’s used in a more selective capacity now because it’s heavier than carbon fiber. It has specific properties that make it very durable, and is much tougher than carbon fiber.
Composite: A combination of multiple materials engineered to attain a specific characteristic. In racing shells, it refers to the fabric or “skins” and the core.
Laminate: The product of combining two or more layers of materials together.
High Modulus: A grade of highly processed carbon fiber with fibers packed densely enough to yield an MSI of 33+. (MSI – million pounds per square inch; a measure of stiffness).
Unidirectional: (Also called “uni”) A material that has fibers running in one direction only. It is most commonly used as carbon fiber, and can come in many different areal weights. It is used where specific reinforcement is required.
Kevlar: A woven synthetic fiber that’s commonly used in body armor and tires. It’s very strong, but extremely difficult to work with, and once damaged difficult to repair.
Pre-Preg Carbon: Carbon that comes with the resin already on it (or “pre-impregnated”).
Wet Lay-Up: Epoxy is hand applied to the carbon fiber.
Lay-up: The combination of materials used to create the racing shell. Each boat builder has their own proprietary lay-up schedule.
Epoxy: A resin that’s mixed with a hardener. Mixed in exact proportions, the epoxy is applied to the carbon fiber. It cures at a specific temperature over a specific period of time.
Resin: A liquid substance that hardens to a hard or enamel-like finish. In this application, resin is applied to the composite material to create the hull of the boat.
Foam: A closed-cell, very strong, very light foam sheet.
Honeycomb: Solid sheeting that is made up of many small hexagonal (six-sided) tubes. It looks just like its namesake – a honeybee honeycomb.
Nomex: The trade name for the honeycomb most commonly used in rowing shells.
316 Marine Grade Stainless Steel: A grade of stainless steel that is resistant to corrosion. 316 refers to the chromium content. Steel is never completely rustproof, however the addition of chromium improves the metal’s resistance. Marine grade stainless is particularly helpful in salt water since salt is a catalyst to the rusting process.
Aircraft Grade Aluminum: A high-grade aluminum alloy that is extremely light, and withstands heat and fracturing well. This is a somewhat broad term covering a wide range of alloys.
Anodized: A process that increases the thickness of the natural oxide layer on the surface of metal. It increases corrosion and wear resistance, and provides better adhesion for paint primers and glues. The process includes passing an electrical current through the alloy while soaking in an acid solution.
The Bottom Line
Everyone wants four things in their racing shell. They want it to be stiff, light, durable, and affordable. It’s impossible to get all of these at once, so the above listed materials are mixed and matched to try to optimize the shell for those characteristics.
We recommend deciding what is important to your program, then weighing the options. Depending on whether you’re focusing on long fleet life, purchase price, hull stiffness, or shell weight, different materials are going to be advantageous.
Want to know more about the evolution and process of racing shells production? Check out our Composite Boats 101 series: