Why Bonded Acrylic Boat Windows Leak — The Engineering Explanation #boatwindows
In this video I explain why saloon window leaks on the Bavaria 37 Cruiser (Farr design) are not simply a sealing failure, but a predictable result of thermal expansion mismatch and constrained movement.
Large smoke-grey acrylic windows absorb far more solar energy than the surrounding white GRP coachroof. Under normal day–night conditions this produces several millimetres of differential movement across a 2.3 m window span. Traditional mastic or polyurethane bonding systems are too rigid to accommodate this repeated shear and peel loading and will inevitably fatigue and fail.
Drawing on façade engineering principles, I break down:
• how thermal expansion and solar loading actually affect acrylic and GRP
• why mastic-only bonding has a limited service life
• how compliant bonding using 3M VHB structural tape accommodates movement
• why a low-modulus silicone edge seal is better suited for weatherproofing
• and how external solar shading can significantly reduce thermal stress
This approach aligns the glazing detail with the real mechanical and thermal behaviour of the materials, resulting in a far more durable solution.
If you’re dealing with recurring window leaks, surveying one of these boats, or planning a long-term fix, this explanation is based on engineering fundamentals — not trial and error.
00:00 Introduction
02:40 “I Can’t Stand the Rain Against My Windows”
05:30 Thermal expansion explained
Sail Safe Guys, Ant & Cid XX 🇬🇧 ⛵️⛵️⛵️⛵️⛵️⛵️⛵️⛵️
Perspex supplier: https://wholesalepos.com/search/results,1-24?keyword=Cast+Acrylic+&x=13&y=15&limitstart=0&option=com_virtuemart&view=category&virtuemart_category_id=0&Itemid=346
===================================================
👋 We’re Ant & Cid aboard SV Impavidus – two adventurers sailing full-time since 2018. From stormy crossings to quiet anchorages (and plenty of dad jokes), we share family-friendly stories of life at sea 🌊
🎥 New episodes every Sunday – honest & safe for all ages.
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We’re currently looking for sponsors to support our video production 🎥
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[email protected]
📺 Our Second Channel
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https://www.youtube.com/channel/UCqYQUohmJ3yLq1zeRd9s3wg
In this video I explain why saloon window leaks on the Bavaria 37 Cruiser (Farr design) are not simply a sealing failure, but a predictable result of thermal expansion mismatch and constrained movement.
Large smoke-grey acrylic windows absorb far more solar energy than the surrounding white GRP coachroof. Under normal day–night conditions this produces several millimetres of differential movement across a 2.3 m window span. Traditional mastic or polyurethane bonding systems are too rigid to accommodate this repeated shear and peel loading and will inevitably fatigue and fail.
Drawing on façade engineering principles, I break down:
• how thermal expansion and solar loading actually affect acrylic and GRP
• why mastic-only bonding has a limited service life
• how compliant bonding using 3M VHB structural tape accommodates movement
• why a low-modulus silicone edge seal is better suited for weatherproofing
• and how external solar shading can significantly reduce thermal stress
This approach aligns the glazing detail with the real mechanical and thermal behaviour of the materials, resulting in a far more durable solution.
If you’re dealing with recurring window leaks, surveying one of these boats, or planning a long-term fix, this explanation is based on engineering fundamentals — not trial and error.
00:00 Introduction
02:40 “I Can’t Stand the Rain Against My Windows”
05:30 Thermal expansion explained
Sail Safe Guys, Ant & Cid XX 🇬🇧 ⛵️⛵️⛵️⛵️⛵️⛵️⛵️⛵️
Perspex supplier: https://wholesalepos.com/search/results,1-24?keyword=Cast+Acrylic+&x=13&y=15&limitstart=0&option=com_virtuemart&view=category&virtuemart_category_id=0&Itemid=346
===================================================
👋 We’re Ant & Cid aboard SV Impavidus – two adventurers sailing full-time since 2018. From stormy crossings to quiet anchorages (and plenty of dad jokes), we share family-friendly stories of life at sea 🌊
🎥 New episodes every Sunday – honest & safe for all ages.
📌 Links
🛒 Shop
https://www.svimpavidus.com/general-5
💻 Website
https://www.svimpavidus.com/
👌 Patreon
https://www.patreon.com/SVImpavidus
🍻 Buy us a beer
https://www.paypal.com/paypalme/svimpavidus
https://www.facebook.com/impavidus.ontheboat.5
▶️ Playlists
https://www.youtube.com/@SVImpavidus/playlists
🌱 Our Philosophy
We live by a “Pay It Forward” ethos – where those taught become teachers, and goodwill multiplies. 🙏
📣 Sponsors & Contact
We’re currently looking for sponsors to support our video production 🎥
[email protected]
📺 Our Second Channel
🎶 Stunning drone footage + eclectic music YOUR DRONE TV
https://www.youtube.com/channel/UCqYQUohmJ3yLq1zeRd9s3wg
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