Topic: A detailed breakdown of the design and engineering process for creating custom composite deck hatches, covering problem analysis, material selection, structural integration, and the use of 3D printing for prototyping and manufacturing.
Author: Shayne and Anna
The original deck hatches on our Catana 42, Paikea, had served for over three decades. While built to last, their design was showing its age: they were heavy, sat proud of the deck, snagged lines, and most critically, had developed a persistent leak that new seals could not fix. The solution was not a simple replacement, but a complete ground-up redesign.
This project showcases the systematic approach we take to engineering problems, where off-the-shelf solutions are evaluated and often found wanting for specific, high-performance applications.
The Problem Analysis: Why Commercial Hatches Fell Short
A thorough evaluation of commercially available hatches revealed that while they could solve some issues, they introduced others.
- Flush Hatches: While solving the snagging problem, many modern flush hatches have known issues with flexibility and strength, particularly in the corners where acrylic lenses can be prone to cracking.
- Weight: Lighter commercial hatches often sacrifice stiffness, making them susceptible to the very same water intrusion problems we were trying to solve.
- Serviceability: Proprietary hinges and hardware make long-term maintenance and repair a potential logistical nightmare in remote locations.
“The commercially available hatches could solve the problems,” Shayne notes, “but they couldn’t solve the cost issue… and they couldn’t solve the weight issue a lot… To go lighter, you go with the lower profile hatches… they’re not as stiff.”
The Design Brief: Defining the Perfect Hatch
Our new hatches needed to fulfill a clear and demanding set of criteria:
- Absolutely Waterproof: Under all conditions, including being cracked open for ventilation in tropical rain.
- Fully Flush: Eliminating snagging points and improving deck aesthetics.
- Structurally Integral: The frame had to reinforce the deck opening, not just fill it.
- Easily Serviceable: Using readily available seals and custom, reproducible components.
- Lighter: A significant reduction in weight from the original 5.7kg assembly.
Key Engineering Solutions
1. The Structural Rim
Unlike a thin metal frame, our new hatch rim is a substantial fiberglass component that is bonded and laminated into the deck. This does not just hold the hatch; it actively stiffens and strengthens the deck around the opening, distributing loads and preventing the flex that can lead to leaks and component failure.
2. Advanced Seal & Gutter Geometry
The design incorporates a precise “sealing blade” that presses into a standard EPDM seal, creating a high-pressure contact line. This is surrounded by a generous gutter to manage any water that makes it past the primary seal. The gap between the lid and the frame was minimized to drastically reduce the volume of water that can even enter the gutter system during a wave impact.
3. Custom 3D-Printed Friction Hinges
After investigating commercial friction hinges, the decision was made to design and print our own from nylon-carbon composite.
“This cleans up so much of my design,” Shayne explains. The hinges provide a constant torque to hold the hatch open without struts and can be easily adjusted, serviced, or completely reprinted anywhere in the world, ensuring lifelong serviceability.
4. The Weight-Saving Lid
The lid itself is a composite sandwich structure. A key innovation was using a smaller, circular acrylic lens instead of a large, heavy rectangular one. This reduces weight in two ways: the composite structure is lighter than a full acrylic panel, and the smaller span allows for a thinner, lighter sheet of acrylic without sacrificing strength or watertight integrity.
The Result: Performance Through Design
The final hatch assembly weighs approximately 3kg—nearly half the weight of the original 5.7kg unit. More importantly, it is stronger, stiffer, fully flush, and designed to be permanently serviceable. It addresses the core problems of leaking, snagging, and maintenance that plagues original off-the-shelf designs.
This project demonstrates that the most effective solution is often not the one you can buy, but the one you can engineer to meet the exact demands of your vessel and your voyage.
Want to Learn More?
This hatch project is a single example of the engineering mindset we apply to every system on Paikea. In the Youngbarnacles Members Hub, we provide deep dives into many of the projects you see on our YouTube channel.
Inside the Members Hub, you will find:
- Deep-Dive Project Videos: Extended content on projects like this, including videos and 3D print files.
- Community Discussion: Engage with us and other members on technical challenges.