Carbon vs. Fiberglass – Building for Performance and Reliability

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When it comes to building or upgrading a cruising boat, the question of materials is never simple. Should everything be carbon fiber? Is fiberglass “good enough”? Recently, we sat down with Shane in the engine room to dive deep into the specifics of our rudder system, tiller arm, and torque tabs. The conversation covered everything from material science and electrolysis to the unexpected rush job that got us across the Atlantic.

If you’ve ever wondered how to balance weight savings, budget, and durability, or how the bleeding edge of America’s Cup technology trickles down to cruising boats, this one is for you.

The Tiller Arm: A Study in “Fit for Purpose”

The core of our discussion revolved around the tiller arm. It’s a monolithic component (meaning no core, just layers of composite), and Shane explained why it isn’t 100% carbon fiber.

While the outside is wrapped in carbon for stiffness, the core is actually fiberglass. The reason is simple: physics. The “neutral axis” (the center of the arm) doesn’t need carbon for stiffness or strength. By using fiberglass in the middle, Shane saved on expensive carbon—a precious resource when you’re in the middle of the Caribbean.

However, there was a twist. Shane’s original idea was to use a fully isolated fiberglass tiller arm to break the electrical potential between the steering system and the rudder (preventing electrolysis). But as sailing projects often go, time ran out. With only six hours to spare before crossing the Atlantic, the arm got a full carbon wrap. The result is a super-stiff arm that works, though it sacrifices that perfect electrical isolation.

The Electrolysis Issue: How We Deal With It

Since we didn’t achieve full isolation with the tiller arm, how do we handle electrolysis? It comes down to the rudder blade itself.

The rudder blade is a solid fiberglass piece (e-glass) with a thin 2mm carbon skin. Fiberglass is often called “e-glass” because it stands for “electrical glass”—it’s a fantastic isolator. By grinding away a small ring of carbon around the bolt holes and using fiberglass plates, the system is effectively isolated. The only contact with the water is the stainless steel bearing shell, and the anodes on the sail drive handle the rest.

Torque Tabs: Metal vs. Composite

One of the most interesting parts of the conversation was about the “torque tabs” (or sheer connections) that transfer load from the rudder stock to the blade.

When we looked at building a rudder stock, the options were aluminum (too much wear), stainless steel, or carbon fiber. While stainless steel is strong, the bonding issue is a nightmare. You simply cannot get a reliable, high-shear bond between resin and stainless steel. Metal rudder stocks require massive tabs to mechanically “glue” themselves to the blade, often using thick, bogged-up glue layers.

With a carbon fiber rudder stock, the game changes entirely. Because it’s composite, you can bond the foam core and the skins directly to the stock. It creates a unified structure. The “torque tabs” become smaller sheer connections because the entire assembly—stock, foam, and skin—works together to handle the torque. This results in a lighter, stronger, and more integrated system.

The Verdict: Asymmetric Rudders and Performance

We ended up crossing the Atlantic with two completely different rudders: the old Valencia-built one (splashed off an America’s Cup design) and the new one Shane built in the Caribbean. The difference in performance was “marked”—a big step forward.

What’s Next? America’s Cup Tech and Cruising

So, why are we back in Spain? It wasn’t the plan. We were heading to Trinidad for a refit, but Shane got a phone call. He’s now deep into running the rig and systems program for an America’s Cup team (working on AC40s and the big 75s).

For us, this is an incredible opportunity to see the future of sailing tech up close. While we have to be careful about what we can share due to protocol rules, we’re excited to look at developments like double-skinned D-section mainsails and advanced foil sections, and ask: How can this be adapted for a cruising boat?

Our goal is to bring that trickle-down effect—taking F1 and America’s Cup level engineering and adapting it to boats like ours. We care about performance, but we also care about reliability and budget. It’s a constant puzzle, but we’re excited to share what we learn.

More details on Paikea’s Rudders

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