Replacing windows (yeah, this old dead horse topic again)...

[MrMikey64]

I need your help again, fellow Mac experts.
I'm in the process of replacing my "rosy" windows with bronze Lexan windows (the "rosy" ones are going to the Mac 25 that I am reparing the fiberglass on).
For those who have done this - on models from 1980 onward, where there are no aluminum frames - what did you find worked best to apply and seal the windows with?
It appears that the original windows were sealed with silicone, but I've also read on here about butyl tape. Then there's always trusty 5200 (I don't think I'll be removing the windows again).

What do you all think about this? What do you use?

BTW, based on an earlier post, I checked into Home Depot for butyl tape or butyl "putty" - out here in CA they don't list either on their computer. But, I di notice that auto parts stores, such as NAPA, carry butyl tape for windshields.

 

[ffaubert]

Re: Replacing windows (yeah, this old dead horse topic again

You should be able to get butyl tape at any RV store. If not, our own MaineSail sells rolls of the stuff.

I'm not too sure how well it would work on windows. It would seal them alright but it might be a little messy (squeeze out).

I'm thinking of putting a wooden frame around mine to go with the handrails.

 

[MrMikey64]

I'm thinking of putting a wooden frame around mine to go with the handrails.

I thought about something along those lines as well, but I really dont want any more woodwork to deal with than necessary. Nice idea, though - I'd like to see how it turns out.

 

[oreana123]

I thought that butyl tape was a sealant only, not an adhesive. Also it (butyl tape) is not clear, but usually black. I replaced my windows with the same sealant/adhesive Macgregor used: RTV silicone seal. 2 years and working fine. John S

 

[MrMikey64]

I thought that butyl tape was a sealant only, not an adhesive. Also it (butyl tape) is not clear, but usually black. I replaced my windows with the same sealant/adhesive Macgregor used: RTV silicone seal. 2 years and working fine. John S

'Nuf said.

Is Permatex a good brand, or is there a better one?

 

[flynfol]

Re: Replacing windows (yeah, this old dead horse topic again

I know this doesn't apply to your windows, but I used butyl tape(light grey) from an RV store(Campers World ?) on my aluminum framed windows(as original) works perfectly. However, the aluminum frame has many screws which hold it/seals against the fiberglass. Not sure it would do the same with the later windows. I found a polyurethane U channel that looks and fits like the original from the glass company that cut my windows. I can dig up the part number if anyone needs it(or email me still have lots left). I think I had to buy 100' and was only $20.

J

 

[rgranger]

When I rebedded my windows (I have aluminum frames) I used plumbers putty. It is cheap and I figured if it can keep my kitchen sink from leaking for 20 years at a pop it should work on my windows. I only have one year of data but so far so good. Not sure how you might adapt that to a frameless window but thought I would put it out there for consideration.

r

 

[HogRyder57]

Re: Replacing windows (yeah, this old dead horse topic again

I need to replace the windows on my 1985 MAC 25... What is a good source for the Bronze Lexan?

Thanks....

 

[Bob McL]

Re: Replacing windows (yeah, this old dead horse topic again

When we had the windshield replaced in our Avalanche, the tech gave me four tubes of the black sealant they use. I am sure an auto specialty store has the same thing. Man does it "hold" and seals.

 

[MrMikey64]

I need to replace the windows on my 1985 MAC 25... What is a good source for the Bronze Lexan?

Thanks....

It took me a bit of searching. I quickly became aware that HD didn't carry anything close to what I needed (I'm using 3/16" smoke lexan).
I ended up finding a deal on eBay, doing a search on Lexan. If you don't find bronze lexan listed, you could inquire if a seller carries bronze or not. Most are happy to create an eBay listing if it means a sale.
Good luck!

 

[brokenfeather]

3m 4000

Just for what it's worth. Found this on West Marine. No I don't work for them.

http://www.westmarine.com/webapp/wc...toreNum=10104&subdeptNum=10325&classNum=10327

 

[timebandit]

Re: Replacing windows (yeah, this old dead horse topic again

I did not save the entire post but this is the gist of it.

Tony on Acrylic vs. Polycarbonate:


"Consider the Following:

• All major hatch, portlight and window manufacturers use Acrylic in offshore / bluewater marine products.
• Acrylic is more scratch resistant than standard (9034) polycarbonate.
• Acrylic is significantly more durable when exposed to Ultra Violet radiation (sunlight).
• Acrylic is less expensive than Polycarbonate.

Don't misunderstand my preference for acrylic. I buy, use and sell a significant amount of both products and each has its application. In my humble opinion Acrylic is more durable, versatile and cost effective in the hands of a skilled craftsman than polycarbonate.

Additional considerations may include polycarbonate with UV and scratch resistant coatings. While these products are heavily promoted by several manufacturers and carry 5, 10 even 15 year warranties the following information has been reported in "real life"applications:

• Polycarbonate is impact resistant. When its new it is almost impossible to break.
• Small quantities (less than a 4 by 8) in gauges over 1/8th inch are difficult to to find in the uv/scratch resistant grades.
• Colors are limited. Only two standards (gray and bronze). Try and find anything thicker than 1/4 in UV/ scratch resistant!
• Polycarbonate foreshortens when subject to static or dynamic loads. What this means is if you replace your hatch lens with polycarb, seal it and then step on it the ductile material will deflect (bow) in the center. One of two things may happen. 1st you will surely break the watertight seal, 2nd you may end up with a leg in your galley.
• As for the warranty: The original owner is warranted against failure subject to the material being submitted to the distributor for evaluation with the original invoice subject to actual replacement cost at the time of purchase. I guess this means they sell you a new square of material and apply the old payment to the new cost. How about the labor to fabricate the part, install it and sealant? Why take the chance?

Polycarbonate is a great material, The US Air force uses it for fighter canopies! I sell Polycarb to the USCG and US Navy. Remember they don't mind using it because we are paying to replace it every three years.
Both Acrylic and Polycarbonate have specific uses and installation requirements.

Cast Acrylic (of a specific thickness) is in accordance with CE and ABYC guidelines, and installed on virtually all of the big blue water sail boats produced on both sides of the pond. Polycarbonate is commonly used as a replacement due to its ease of fabrication and incredible initial strength. The USCG and USN require Polycarbonate on their vessels but they also have a PM cycle of 36 to 42 months for change out. My Tax dollars at work...

Due to its ductility Polycarbonate it is more challenging to install. I have seen Sika Flex 295UV with primer and Dow 795 both mentioned. I use and recommend both. Dont go over 4 ft continuous length with a fixed portlight. Remember the coefficiant of thermal expansion for Acrylic and Polycarbonate is in the neiborhood of .000039 per inch per degree F. That means an 8ft plastic port will expand and contract up to 1/2 of an inch from the coldest day in Feb to the hottest day in summer. WOW!! Compartmentalize the job. It will be easier to install and less prone to leaks.


Tony on Screwing or Through Bolting:

Never ever bolt a plastic portlight in place. Screws are fine to hold a lens till the adhesive cures. Take them out asap and fill the holes with the afformentioned products. Both of these products are rated at 700 + percent elongation before tear. Strong flexible and UV resistant. Been to a boat show lately? Seen any screws? "

Tony on Sealants:

"I hear the question as to which sealant to use when bonding Acrylic, or Polycarbonate to aluminum, stainless or FRP over and over and over.....

Well here goes... The only three adhesives I would consider using are Sika Flex 295 UV with the primer, GE SG-4000, and Dow 795. Using the correct adhesive is only 1/2 the battle. Do not apply the sealants below 50 degrees F. The temperature must maintain at least 50F during the entire 21 day cure cycle. Cut this corner and your finished before you start. Preparation of the bond area is also very/ very important. DO NOT TOUCH THE BOND AREA WITH YOUR BARE HANDS! Contamination from the dirt and skin oils will make a solid cure impossible. You may clean the FRP and metal with acetone to prep the area but if you touch the Lexan or Plexi with harsh solvents you will ruin the portlight. A 50/50 mix of isopropal alcohol and distilled water will work well to clean the plastic if needed. Remember that clean enough is not clean enough."

 

[MrMikey64]

Re: Replacing windows (yeah, this old dead horse topic again

Wow - I wish I had known about this article prior to purchasing and prepping the Lexan for installation. I guess they won't take it back now...

 

[oreana123]

Who is Tony and why should I care?

If you wish to mount a lens with screws, make the screw holes oversize to allow thermal expansion. I cut a large hole in the forward hatch of my D Mac and mounted a piece of clear plastic with a series of screws, about 50 in all. This boat has been radiated in the sun for years, walked on and no cracks and no leaks. You don't see this kind of design at boatshows because it is labor and material intensive. Oh yeah, sealed with RTV silicone.

For the cost, for the effectivness, RTV silicone was the choice of Macgregor. It is a clear, long-lived sealant and it is very tolerent of touching the seal area, it is available anywhere. I do not ever expect to need to rebed this hatch lens- the RTV silicone seal used by the manufacturer was incredibly strong when I removed the side window lenses after 20 years, I broke all of the lenses removing them for new ones. YMMV

 

[timebandit]

I just saved the working part of discussion so I blinged the part numbers ans came up with this----he might know a thing or two.

http://www.selectplastics.com/index.php/Home.html

Who is Tony and why should I care?