Leaking Fixed Portlight

[dsiegfried]

I have a fixed portlight on each side of the cabin (approximately 10" x 30"). The plexiglass is through-bolted to the hull without a frame by way of holes drilled through the plexiglass & hull. There is a foam gasket between the plexiglass and hull.The problem is the plexiglass expands and contracts enough it cracked the corners off the glass at the corner bolts. Also, the foam gasket degrades with exposure to UV. Result? IT LEAKS! I've replaced the glass and tape twice in 10 years and it needs it again. Beneteau tells me they haven't got any better ideas.I read in DIY about adding external frames and bedding the glass without bolts in a special DOW sealant. Anybody know where to buy custom frames?

 

[Gord May]

Leaky Portlights

LEAKY WINDOWS:Portlight (& Hatch) leaks are often the result of movement between the glazing and the structure, which can result from:- Weak structure that flexes.- Different coefficient of expansion (structure vs window), which is exacerbated by dark tinted glazing in hot climates.- Installation of a flat panel on a curved surface (without a perimeter shim).Caulking degradation (& subsequent leaks) may be caused by exposure to ultraviolet light, movement, or mere age.Glazing “break-away” (at edges & around fastening holes) could have one (or a combination of) two prime causes.- Unsupported glazing perimeter edges. Although plastic glazings (Polycarbonate & Plexiglass) are very strong - they do require firm support around their perimeter.- Spider-cracks radiating outward from mounting holes (or holes too near perimeter) will also cause “break-away”.If you have (or have created) a perfectly flat surface surrounding your window opening, and no structural flexure; you could use a " Primerless Super Fast Urethane Auto Glass Sealant”, such as 3M part #08609 to bond the glazing into the structure. It’s made by 3M’s Automotive Trades Division, and is sold by companies who supply body shops and auto glass shops (almost all auto paint wholesalers carry it). First prime with 3M Super Fast Urethane Primer, part #08608, for UV protection of the bond (this is another reason why the bond fails in many of the hatch frame separations - UV degradation of sealant).Another alternative is to get a complete new window & frame assembly. This might require modifying the existing opening (enlarging). Search out Hatch & Window manufacturers such as:Aluminum 2000 IncArrowhead PlasticsBeckson MarineBomarImtra New Found MetalsScandvikTaylor Made SystemsVetusetc.See also some on-line articles:The Practical Sailor Article - “Converting Windows to Opening Ports” by Paul E. Ringhttp://www.practical-sailor.com/newspics/charts/907windows.pdfThe Sailnet article - “Resolving Hatch and Portlight Problems” by Tom Woodhttp://www.sailnet.com/collections/articles/index.cfm?articleid=woodto0167HTHGord