Sven Yrvindvideo
25 Nov 2025 Composite vs keelbolts Wich is stronger
November 24, 2025 · 4 min · 2K views · Stockholm, Sweden
What this video covers
Sven Yrvind addresses the common objection that epoxy composite is too weak to secure a keel without keel bolts, then works through the numbers to refute it.1:47 His keel attachment uses epoxy rated at 2.5 MPa — 22.4 kilos per square centimeter — over a bonding area he estimates at roughly 1,000 square centimeters (150 cm long by 10 cm wide, shaped), yielding 22,400 kg of holding force from the epoxy alone.2:46 He then adds fiberglass on the outside at approximately 5,000 kg per meter across three meters of surface (two sides of a 1.5-meter keel), contributing another 15,000 kg.3:23 Combined holding force: 37,000 kg against a bronze keel weighing 75 kg — a margin of nearly 500 to one.4:07 Earlier in the segment he polishes the bronze keel surface and countersinks the bolt hole, and briefly grinds and longboards the hull exterior at Ordno to improve fairness.0:01 The calculation shows composite bonding outperforms keel bolts by orders of magnitude for this load case.3:41
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