Key Message: Even with professional knowledge, hands-on projects are a process of problem-solving. The goal is a functional, lightweight part, and sometimes that means making—and fixing—mistakes along the way.
Author: Anna & Olly
Introduction
This project was born from necessity: four days of pump foiling with an old kiteboard wasn’t cutting it. The solution? A quick, custom-built carbon foil board. This isn’t a slow, perfect refit; it’s a rapid prototype that demonstrates core composite principles in a real-world, fast-paced build. We’ll cover the laminate, a clever bagging technique, the inevitable errors, and the final, successful result on the water.
Materials & Tools
This project was built using professional-grade materials, many of which were scraps from our Paikea refit. For those looking to replicate this build, here is a full list of the essential components we used, with links to our preferred supplier, Easy Composites.
- Core Material: PVC Closed-Cell Foam (Easy Composites)
- Resin System: EL2 Epoxy Laminating Resin with Slow & Fast Hardeners (Easy Composites)
- Reinforcement: 200g 2×2 Twill 3K Carbon Fibre Cloth (Easy Composites)
- Project Note: We are still experimenting with laminate stiffness. For less flex, a heavier cloth weight may be beneficial.
- Vacuum Bagging Consumables:
- Breather Fabric (Easy Composites)
- Vacuum Bagging Film (Easy Composites)
- Peel Ply (Easy Composites)
- Tacky Tape (Easy Composites)
- Perforated Release Film (Easy Composites)
1. The Build: Envelope Bagging for Complex Geometry
For this board, we used a technique called “envelope bagging.” Unlike standard vacuum bagging where the bag is sealed directly to a table, the part is completely sealed inside a bag, like an envelope.
- Why This Method? The bottom of the board had bevels. If we tried to bag it directly to a flat table, the bag would bridge these bevels, creating voids and uneven pressure. The envelope ensures the vacuum pressure is applied uniformly across the entire complex shape.
- The Process: The pre-wetted carbon laminate was placed on the foam core, followed by peel ply and breather. The entire assembly was then sealed inside a vacuum bag, creating a pressure chamber around the part.
2. The Inevitable Hiccups: Sanding and Drilling Errors
No project is without its lessons. We encountered two classic composite workshop errors:
- Sanding Through the Laminate: While trimming the edges, we sanded through both 200g carbon skins, right down to the foam core. The cause? The vacuum bag had pushed the top layer slightly beyond the bottom layer, creating a trap for an over-zealous sander. This highlights the importance of careful, measured sanding, especially on thin, high-performance skins.
- The Accidental Drill Hole: A measurement error when drilling holes for the base plate led to a hole in the wrong place, going straight through the carbon and into the foam. This is a common risk when working without a drill jig and reinforces the need for double-checking layouts before committing.
The Fix: Both issues were repairable. The sand-through was patched with a small carbon piece, held down with tape acting as a temporary vacuum bag. The errant drill hole was simply filled with resin during the final assembly. These are not catastrophic failures, but part of the iterative process.
3. Finishing and Assembly: The Devil in the Details
The final stages are what separate a rough prototype from a finished product.
- Surface Finish: After a repair and a final light laminate, the board was wet-sanded up to 1200 grit to prepare it for polishing. This creates the smooth, low-friction surface essential for a water board.
- Weight Management: The final board, including all laminates, resin, and hardware, weighed in at a respectable 900 grams. We monitored resin use closely, applying only 50g for a final coat to avoid unnecessary weight.
- Precision Assembly: To ensure perfect alignment for the expensive base plate, we used 3D-printed inserts as guides. These inserts allowed us to accurately drill the final bolt holes without risking misalignment and damaging the carbon board or the plate.
4. The Payoff: Successful Foiling
The ultimate test for any project is its intended use. After the repairs, finishing, and careful assembly, the board was taken for its maiden voyage. Despite a initial challenge of stepping off the front, the board performed perfectly, getting up on the foil and proving the design and construction were a success.
Conclusion: Embrace the Process
This pump foil board build is a perfect example of practical composites. It demonstrates that you don’t need a perfect, sterile environment to create a high-performance, functional piece. You need a solid understanding of the principles (like envelope bagging), the humility to fix mistakes (sanding and drilling errors), and the attention to detail in the final finishing (sanding, painting, and precise assembly). The result is a lightweight, custom piece of gear built for a fraction of the cost of a commercial board, and the satisfaction of having built it yourself.
Want to see more on Olly’s Board?
Follow Olly’s obsession with everything foiling here on his channel https://www.youtube.com/@OliverYoung123
See the first half of his build of the pumpboard in more detail in this video