Coachroof, windows and portlights are where boats leak most. A leak does not just wet the interior; it reaches the deck core and interior joinery. On motor yachts, large bonded windows are also a safety matter.
What is checked
- Acrylic and polycarbonate
- Crazing, clouding and cracks around screw holes; sunlight degrades these materials over time.
- Sealing
- Dried, cracked or separated seals and sealant.
- Frames
- Corrosion and white powdering on aluminium frames; play in hinges and latches.
- Hatch seals
- The seal seating fully when closed; latches working.
- Bonded windows
- Adhesive separating at the edges and glass damage; the safety of large panes in heavy weather.
Finding a leak
- Trace. Stains and lifting on linings are traced upwards; the source is often higher than it looks.
- Moisture. The deck core is read around portlights and hatches.
- Water test. With the owner's consent, water is run outside and watched for inside.
Repair
Cracked acrylic is replaced; a leaking portlight is removed, cleaned and rebedded. Bonded windows are renewed with the maker's adhesive system and surface preparation.
What we often see
- Leaks at portlights and hatches: Water staining and lifting of the interior lining below the portlights.
Acrylic and toughened glass
Boat windows are usually acrylic or toughened glass. Acrylic is light and impact-resistant but over years in sun it scratches, crazes and develops fine cracks. Toughened glass resists scratching better but can shatter completely on impact. On survey, each window's material, cracks and scratches, crazing and the frame or bond line are examined.
Bonded windows
On many modern boats, windows are frameless and bonded directly to the hull. As the adhesive ages, a window can leak at its edge or separate. Gaps at the edges, cracking in the adhesive and water marks inside show renewal is near. A bonded window must be renewed with proper surface preparation and the maker's recommended system.
Portlights
On opening portlights, seals, hinges and catches are checked. When a seal hardens, the portlight leaks even when closed. Keeping portlights near the waterline closed at sea, with seals in good condition, is part of safety.
Coachroof
The coachroof carries load with the deck and, if sandwich construction, needs moisture checks around fittings. Cracks at the coachroof-deck junction can signal structural movement.
Water test
If a leak is suspected, windows are hosed from outside while watched from inside; where water enters is found that way.
Safety
On boats going offshore, storm boards for large windows are considered.
Maintenance
Acrylic is cleaned with products safe for it; some cleaners and sealants attack acrylic and cause crazing, so the maker's list is checked first.
Crazed or cracked acrylic is replaced, since it reduces visibility and strength; the new window is chosen at the original thickness or as the designer recommends. The seal around each window is checked by eye each season, and a small gap closed early saves a large repair.
Window condition is also a visible part of a boat's appearance and value. Crazed, scratched glazing gives an impression of neglect even on a well-kept boat; renewed, the boat looks safer and worth more, and buyers notice at first glance from the pontoon.
Renewal is usually a winter job, done ashore in dry weather, which directly affects bond quality.
The adhesive's full cure time is respected before the boat goes back to sea or is washed down.
Patience here pays off for many seasons to come.
Good glazing is quiet: no drips, no whistle and a clear view out in any weather.