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Kennneee

Polycarbonate or Arcylic?

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Hi Guys- I am sure this has been discussed before but some advice would be appreciated.  I am about to buy the plastic for my sliding pilot house windows, door, etc.  Can't decide if I should go with Acrylic or  Polycarbonate.  I know acrylic is more scratch resistant but more inclined to break that polycarbonate.  I thought the choice was settled when the price difference was almost 2x at my closest supplier ($375/sheet for polycarbonate).  I just found another option where the price difference isn't that big ($275 plus $60 shipping).  I  have some smoke gray polycarbonate for the oval windows that Graham and Alan cut for me on their CNC machine so those are already covered. Any input appreciated.

Ken

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I've always come to the conclusion that Acrylic a bit thicker is a better choice. I've had too many cases of crazing and scratches over the years to justify the benefits of Poly-carbonate. We all want tough, but it takes a lot to break the small panels we use for port lights and other stuff. There is a good summary here: http://highlinepc.blogspot.com/2009/12/acrylic-sheet-and-polycarbonate-sheet.html

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Ken,

 

Based on input from various forums and my plastic supplier, I’m of the belief that polycarbonates are more susceptible to UV damage and scratching but are stronger in impact situations.  Last week I was on a tour of a Naval Academy 44’ training sloop.  These boats are built with safety  being the number one priority.  The dead lights were polycarbonate and heavily frosted over perhaps from UV.

 

i used acrylic on my Bluejacket.  A very respected poster on the Woodenboat Forum says that when cutting or drilling acrylic, stresses are introduced that later will cause cracks in the material.  The poster says that after working the material, put it in an oven for  one hour at 200 degrees to anneal it.   Lacking experience with plastics,  I have no basis to question the poster’s advice.  

 

However,  use of Ann’s kitchen applicances for project work is no longer an option for me after I used the microwave oven to “kiln dry” a piece of wood off my sailboat when I recently replaced a depth sounder transducer.  The transducer wood  spacer block was  too damp to put three coats of waterproofing epoxy on it.  After four minutes of cooking, steam came out of the microwave and the wood was light and much drier. Consequently, the genius decides that  if four minutes of microwaving was good then three more minutes would be even better.  

 

I hit the start button about the same time I hear Ann arrive home from grocery shopping so off I head to the driveway to unload the car.  Returning to the house I’m greeted by heavy smoke and smoke detectors going off. I head for the microwave and gag on the smoke.  Two glasses of water were needed to knock down the flames in the microwave.  The first and second floors were filled with smoke and Ann stayed  in her air conditioned car for  30 minutes until fans cleared out the smoke. Scary indeed how much smoke was generated from a burning 1 1/2” by 3 1/2” X 5” piece of pine.  A wake up call on how a “minor”  house  fire can quickly overcome the ability to breath.  

 

For a week the house smelled like a forest fire and to my surprise, after rigorous scrubbing of the microwave, it is usable though the revolving glass plate has permanent burn marks in it.

 

Ann was very restrained after my wood drying experiment in that the worst she said was “What is wrong with you”.  During my college years I had a Volkswagen Beetle engine  block in the bathtub of our apartment for steam cleaning.  She was satisfied with my promise that the engine would only be there for two days thus she showered along with it.  However, Ann’s goodwill needs no further testing by putting my Bluejacket acrylic windows in her kitchen oven.  

 

One 2’X2’ fixed acrylic window in my Bluejacket has holes drilled in the perimeter and attached with screws.   The other window is held temporarily in place with butyl tape but will will be redone with 3Ms VHB tape and no screws.    It will be an interesting science fair project to see if the material cracks.  

 

Regards,

Dave

 

P.S.  Your wood work, especially the galley cabinets, is an inspiration for me to step up my game when in December I return to finishing my Bluejacket’s interior.

 

 

 

 

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Dave- Your microwave adventure sounds like a great "learning experience"  I am probably one of the last humans on earth that has never owned a microwave.  Years ago I wound up on the west coast of Florida after a rough passage from the Panama Canal.  We hadn't been among the "civilized" in years and were thrilled when an old friend offered his fancy home on a canal for us to tie our boat to and take care of while he was away.  The first night we reveled in the idea of a washing machine and dryer, the ability order a pizza and a microwave to heat up other foods.  Well in the course of around 15 minutes I stupidly put something with metal in the microwave, the dryer buzzer sounded and so did the doorbell when the pizza arrived.  We had a small dog and he started barking..... All of the noises almost caused us to head back to sea!

Luanne likes to roast our coffee from green beans.  She is quite diligent with everything she does but a few months back forgot about the coffee roasting in the kitchen and started pruning the roses.  Long story short, the house filled with smoke and we were lucky that it didn't burn down.  She spent 3 days scrubbing the walls, ceiling, etc.  I think I might be able to use the oven for important things like annealing boat windows after that without getting any grief. Does using someone else's misfortune to my benefit make me a bad person? No answer required.

Well Dave, I look at your pics and it makes me step up my game as well. Let's keep that inspiration bouncing back and forth.

Ken

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It used to be that acrylics were just not strong enough, so their scratch, yellow resistance didn't add up high enough.  It is no longer the case.  Even overhead hatches are being made with acrylic now.

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