|Topic Review (Newest First)|
|03-29-2009 01:32 PM|
"they had it in stock and I did not need to buy a whole sheet. " What riles me is that almost all plastics shops will indeed charge you for the whole sheet--even if they don't sell or deliver it to you. I know, it has to sit in inventory until someone asks asks for the stuff...but if I'd paid for the sheet, I want the sheet.
Even on a coastal boat, there are reasons to consider structural glazing instead of what the builders use. They have to skimp on costs or else they're out of the market. But, even coastal, what happens if a storm hits and your whisker pole breaks free and shoots through your portlight?
I'd rather follow the conclusions after the Fastnet disaster, i.e. that the entire cabin top, doghoise, whatever, be fully as strong as the hull itself.
Or at least, as strong as the screen doors on a submarine.(G)
|03-29-2009 02:31 AM|
yes for smaller boats windows i dont think it will make much difference. personally i would not go over about 12 by 12 with acrylic unless 3/8 or thicker. i want the poly for the boards for security reasons, and remember it will not be for holding back a wave. i plan on using 3/16 because i can get it locally for pretty cheap and in my case i want the flex
i have seen the results from a companion board made from 1/4 inch acrylic kicked in, i did it on a boat that got donated to the charity that i bought my boat that i was looking at. it did not take much and there where pieces found in the v berth. ( breaking it was with permission )
|03-29-2009 01:51 AM|
Originally Posted by scottyt View Post
This is an O'day for coastal sailing and they are small windows. Considering just about every sailboat builder out there and every hatch manufacturer uses Acrylic, and has been for a long time, and you can't get Lexan in many thicknesses, with UV and scratch resistance, why would you suggest Denise reinvent the wheel so to speak?
I sailed in the Perfect Storm aboard a Shannon using acrylic hatches, as most all do. We took a serious pounding and never even came close to imploding those hatches.
A friend of mine here in Portland own a fleet of commercial long line boats (Deadliest Catch type steel fishing boats) and they too use Acrylic on board. Builders like Hinckley, Swan, Morris, Malo, Halberg Rassy, Shannon, Passport, Hylas & Valliant and hatch makers like Bomar, Lewmar, Goiot, Adkins & Hoyle, Hood, Nibo and others all use acrylic. I can't remember the last time I heard of a hatch or acrylic portlight imploding. Perhaps it's happened but I'd venture to guess Denise will not be out in 40 foot seas.
I think on any small coastal cruising boat the biggest priority is keeping a seal and preventing UV damage. As Tony D'andria states (owner of select plastics) Lexan flexes too much under foot and you can risk breaking the seal by simply stepping on a hatch. There is a big difference between impact resistance and flex. Flexing under foot or wave can break seals on polycarb hatches.
The hatch glass that just came out of our boat is 30 year old & acrylic. I could still walk on it but barely see out of it. The boat has tens of thousands of miles on her and 5+ years of circumnavigation/cruising. I stayed with acrylic because it works, is strong, and lasts a long, long time, 30 years long.
If Denise needs to replace port lights ever 30-40 months I don't think that is a wise investment.
Make your own decisions but before you do please pck up teh phone and call Select. I too wanted Lexan before I learned the pros & cons..
|03-29-2009 01:24 AM|
not stirring the pot here
personally i would go with poly. i have seen acrylic basicly explode under pressure, it will flex to a point then bust with force enough to stick a shard thru drywall. if you want strength with scratch resistance use tempered glass, over a certain size it will be cheaper to use glass.
if you are doing pilot house windows, size em to use school bus rear windows, i bet with some searching at scrap yards they would be very cheap
i will be doing some companion way boards soon with poly inserts like a raised panel door. for privacy i plan on getting some of the self adhesive child sun blockers like this stuff here but my windows will be about 12 by 18 so it wont need much thickness
|03-29-2009 12:59 AM|
Originally Posted by hellosailor View Post
I'm fortunate enough to have a good plastics company up here in Maine. I just replaced the glass in two Goiot hatches for under $300.00 using Acrylite GP. This included the CNC cutting and everything and they had it in stock and I did not need to buy a whole sheet.
Select plastics is a great source and they have rebuilt hatches for me before. The last time I spoke with them they could not get Lexan in 3/8" or 1/2" smoke with scratch resistance and UV. They also convinced me to not use it due to the potential for bonding failures due to the flex characteristics. They basically said if you can't get UV polycarb not to bother as it will be a waste of money on a boat..
In terms of plastic hatches & port windows Select Plastics is probably one of the most knowledgeable companies in the industry and are the largest in the world who do hatch repair..
|03-29-2009 12:34 AM|
"The USCG and USN require Polycarbonate on their vessels but they also have a PM cycle of 36 to 42 months for change out."
So, do you think that's all pork barrel spending? Or, that poly really is superior provided you have the budget to maintain it?
Whether it is acrylic or poly, genreally if you want anything beyond the most common grade of clear stock, it seems you have to order in full 4x8 sheets. Only the largest of suppliers (who generally won't be local) carry anything that has special qualities, But something like GE MR10 poly (scratch and Uz resistant) will be commonly available to them, as it is a standard for architectural and other uses--like train windows, which are required by federal law to be bullet-resistant. (Go figure, the train itself doesn't have to be, but the windows do.)
|03-28-2009 04:40 PM|
Originally Posted by deniseO30 View Post
You really should be using Cast Acrylic.
Not my words these are the words of Select Plastics..
|03-27-2009 12:15 AM|
Matt, call GE's toll free number. Ask the lexan ("structured plastics") division and the silicone sealants division if you can use silicone seal to glue Lexan to fiberglass.
I'm fairly certain they will all tell you NO WAY. Silicone products simply do not bond to Lexan, you not specific adhesives and often primers for them, or the Lexan will rather quickly unbond from the adhesive.
A couple of free phone calls will save you from a major redo.
|03-27-2009 12:09 AM|
Lexan is predrilled
Originally Posted by cutterorient View Post
I think I will try replacing one of the windows and in the process it will become clear whether it has sufficient adhesion and whether the other windows need replacing.
The lexan overlaps the outside of the windows by about 4 inches all around, so quite a bit of surface area attachment.
I read somewhere that if the lexan overlaps the fiberglass and you don't want to see all the goop behind the lexan then you should paint the back of the lexan where it overlaps. But I am not sure what paint to use?
|03-26-2009 11:39 PM|
Go ahead with the 3/16 lexan. Lexan is very, very tough. Once it's on, I doubt you could break it with a hammer. If it's plexi, on the other hand, you need to go thicker.
I have folded lexan in half in the vice without breaking it.
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