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Old 16-05-2010, 18:45   #1
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we went and looked at a hunter sailboat today and all the hatches and fixed glass were all was awful, why does this happen, and with what material do you replace it with so it wont happen again.

just wondering incase I go with it....thanks
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Old 16-05-2010, 20:42   #2
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It is pretty common and occurs on any boat because the acrylic crazes over time from UV light and temperature expansion/contraction. It cannot be polished off as the crazing occurs inside the acrylic so replacement is required. My dock neighbor's Catalina 400 is 7 years newer than my boat and his hatches and ports are virtually impossible to see through except for dull shadows.
I wouldn't consider this a negative if the boat you are considering is otherwise to your liking as no matter what boat you buy, it will happen sooner or later.
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Old 16-05-2010, 21:03   #3
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This one drove me (more) nuts

Try this. You'll see me whimpering as I go thru this part of my learning curve.

Crazing is not supposed to happen. As I see it, it starts with boatbuilders saving money by using extruded acrylic as opposed to cast. There are other contributors downstream of that of course.
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Old 17-05-2010, 03:13   #4
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"... Crazing in acrylic is caused by either thermal or mechanical stresses, imparted during production, transport, manufacture or in use.

Acid rain,Ultra Violet degradation, Windex or the boat detailer's magic deck cleaner (to name a few) accelerate the process.

Once somthing is crazed it is significantly weaker than the same part in factory OEM condition.

How do you stop it? Make sunbrella covers (not vinyl backed sunbrella!!). Use cleaners specifically designed for Acrylic.

How do you repair it? You don't ..."

More ➥ Crazing Acrylic
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"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"

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Old 17-05-2010, 04:50   #5
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Most important to keep petroleum distillates like paint thinner off the windows and hatches, as they accelerate the process--you won't see immediate crazing, but it will be there in a year or so.
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Old 18-05-2010, 15:39   #6
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Yes "crazing" or the little spider cracks/webs type surface degradation is unavoidable in plexiglass (acrylic, lexan, etc.) as time and UV exposure eats at the material. Covering the hatches, etc. with opaque material like sunbrella will stop the process - except - that the whole idea of having the hatch is to let sunlight into the boat without having to open the hatch.
- - I have successfully "polished" away the surface to remove the crazing, but any hand or machine polishing introduces distortions in the surface level which is visibly noticable. So the easy way is to just replace the old plexiglass with new. There are super strong coated plexiglass material that greatly resists the natural crazing, but the costs of the material is extremely high versus plain ole acrylic plexiglass. It is more cost-effective to replace with the ordinary material than go with the "super" stuff.
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