How Water Proof Are Boat Fabrics?

At SewLong, we pride ourselves on going the extra mile to understand the performance of the fabrics we use. When Justin’s son needed a science project, we saw an opportunity to test the water-tightness of our fabrics—and involve some youthful curiosity in the process.

The test was simple: we made small “bags” from five popular fabrics (Aqualon Edge, Top Notch 9, WeatherMax 80, Recacril, and Sunbrella), secured them to buckets, and poured in one gallon of water. Then we watched and waited overnight.

Test 1 – New Fabric Performance

You can watch a timelapse of the New unused fabric over 24 hours here.

By morning, most buckets were still nearly full, but there was some water bead formation on the undersides of the fabrics, showing minimal leakage. Here’s how the fabrics ranked:

1. Aqualon Edge: Minimal leakage, as expected from a coated fabric.
2. Sunbrella: Held up well, with only minor seepage.
3. WeatherMax: Comparable to Sunbrella, with slightly more leakage.
4. Recacril: Performed similarly to WeatherMax.
5. Top Notch 9: Surprisingly, this fabric allowed the most water through.

This was a bit of a surprise, especially since we frequently use Top Notch 9. However, we weren’t ready to write it off just yet.

Test 2 – Worn Fabric Performance

You can also see how the Worn fabric performed under identical conditions here.

To simulate wear and tear, the fabric samples were washed in a machine with two towels (spin cycle, no detergent), air-dried, and then retested. We expected performance to degrade across the board. Instead, we were astonished:

• Aqualon Edge maintained its top position with minimal increase in leakage.
• Top Notch 9, to our surprise, performed better after washing than it had when new!
• Sunbrella stayed consistent, outperforming Recacril and maintaining solid results.
• WeatherMax and Recacril showed slight increases in leakage but were still reliable.

Insights and Questions

The results left us both impressed and curious. Why did Top Notch 9 improve after washing? Does wear somehow “tighten” its weave? These findings have spurred additional questions for our team, including:

• Should we prioritize new fabric performance or durability over time?
• How do fabric treatments like 303 Fabric Guard or Aquatite impact performance?

We also conducted a similar test, focusing specifically on the water resistance of fabric seams rather than the material itself. This experiment aimed to understand how different seam constructions held up underwater exposure, simulating real-world conditions. The findings revealed that seam design and thread selection play a crucial role in maintaining water resistance, especially in marine environments where durability is essential. To learn more about our seam-testing methods and results, check out our detailed analysis at The Leaky Seam.

What’s Next?

We’re planning more tests to answer our other questions, including stress tests for stretching and deformation, as well as trials on coated products. Our goal remains the same: to ensure our customers have fabrics that meet their unique needs—whether it’s for long-term storage, travel, or everyday use.

Stay tuned as we continue exploring the best materials for your boat covers. At SewLong, we believe the best solutions come from a blend of curiosity, innovation, and a commitment to quality.

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