broken windon

[dolphin]

good day to all !
due to maintenance requirement all windows were removed, the surface treated accordingly and again fix in place. one of the window was replace because was broken.
20 days after fixing the windows, the new one had few cracks and one of other windows, had only one !
the material is perplex and the fixing method is direct to the hull with bolts and between window and hull is sufficient quantity sikaflex!
i need to change at least one of the windows but before to fix the new one, what can be the reason that the material crack?
the boat is on dry all the time!
any idea is welcome as i do not have any explanation either the person fixed the window!
thanks and brgds

 

[VicS]

Presumably you mean Perspex. ie acrylic

Cracking may be due to the effects of a solvent although I think polycarbonate is more prone to that problem than acrylic. Not cleaned them with any solvent ?

Holes for fixing bolts if not sufficiently oversize can result in cracking

Countersunk fastenings can cause cracking

Exactly what type of Sikaflex did you use ... Sikaflex 295UV is the correct one for use with plastic glazing

 

[exfinnsailor]

There are different types of sheet. Some are very brittle and scratch resistant others are soft and bendy. You also find it goes very brittle in the sun and cracks in time. You need to talk to a supplier and ask for recomendations