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-   -   Experience installing portlights without fasteners? (http://www.sailnet.com/forums/gear-maintenance/100430-experience-installing-portlights-without-fasteners.html)

Beersmith 06-13-2013 10:19 AM

Experience installing portlights without fasteners?
 
I am about ready to install some largish portlights/windows on my boat and am looking for other people's experience with this particular type of installation.

I plan on following these instructions: Hints For Replacing & Sealing Acrylic Boat Windows | THE PLASTIC SPORK BLOG

it is sort of a modified version of the "Sexy Windows" method that has been discussed here: How to install boat windows and port lights

instead of using the tape, it relies on the Sikaflex for the whole bond. The Sexy Windows article even mentioned in the updates that he might go this route of not using the tape.

My biggest concern was that the bond is only as good as the paint on the cabinside, so I plan on grinding off all of the paint under the windows so it will be bonded directly onto the gelcoat.

Of course the alternative would be to thru-bolt the ports, still using the Sikaflex with spacers. However, the methods in the links above are designed so that no fasteners are needed, which is where leaks seem to show up.

Has anyone had experience good or bad with bonding ports without fasteners?

thanks

copacabana 06-14-2013 10:43 AM

Re: Experience installing portlights without fasteners?
 
Beersmith, are you talking about bonding frameless plexiglass portlights or do they have a frame to sit in? If they are frameless, I think you might want to consider through-bolting them to the cabin sides, especially if you plan to go offshore.

Beersmith 06-14-2013 11:51 AM

Re: Experience installing portlights without fasteners?
 
Quote:

Originally Posted by copacabana (Post 1043974)
Beersmith, are you talking about bonding frameless plexiglass portlights or do they have a frame to sit in? If they are frameless, I think you might want to consider through-bolting them to the cabin sides, especially if you plan to go offshore.

Thanks! yes, they are frameless and I do plan on going offshore.

zz4gta 06-14-2013 03:51 PM

Re: Experience installing portlights without fasteners?
 
Dow Corning brand, silicone # 791

Only think holding on my windows and it's the only think that actually stuck to both acrylic and the gelcoat. I honestly don't see the tiny lip generating enough leverage or force to rip off the rest of the window.

Faster 06-14-2013 04:21 PM

Re: Experience installing portlights without fasteners?
 
zz... is DC791 a better adhesive than 795?

f182 06-14-2013 05:05 PM

Re: Experience installing portlights without fasteners?
 
I have used a different product here in Aus. Have look at the FixTech products and a product FS200. Have used this system on Gallivant with great results.
Web site fixtech.com - fixtech Resources and Information. This website is for sale! contains a usefull installation guide. Found clean up easier than other sealants.

zz4gta 06-17-2013 11:46 AM

Re: Experience installing portlights without fasteners?
 
Going by the product sheets it looks like both are very similar. I believe I used 791. I was specifically concerned with the adheasion to gelcoat/fiberglass and acrylic. Which ever one stuck better to both of those materials was the one I used.

Silicon, 4200, and other sealants didn't last more than a couple months. Just routine sailing wouldbreak the seal and I used mineral spirits to desolve it. The Dowel Corning stuff is like contact cement. I don't know how on earth I'll ever get them off, but they sure aren't leaking either...

KBuckley 06-17-2013 04:10 PM

Re: Experience installing portlights without fasteners?
 
I can't yet tell you how they will last but I just replaced all 8 windows on my '81 Yamaha 30 - just DC 795 surface mount - no fasteners. I followed the advice posted by Maine Sail here (http://www.sailnet.com/forums/1000233-post16.html) and followed the Dow Corning data sheet for DC 795. I purchased the 795 from my local glass shop as none of the marine stores in the area sell it. (!)

I was deterred from using SikaFlex 295UV by the data sheet recommendation that the joint be masked from sunlight to prevent degradation from UV.

I used rubber washers as spacers to ensure I had the bead thickness recommended for my window dimensions (6-8mm). DC 795 is cheap (<$10) for a 300 mL tube. Which is good because I used 20! I tried to get cast acrylic but in my tint it is apparently a custom run. My plastic supplier lead me to believe he had sourced it but when I unpacked the windows at the boat the material designation was for extruded. I complained but went ahead and installed it. I have 1 more week of curing to wait...then in a month, year, or a decade I will know how it worked!

Beersmith 06-24-2013 10:36 AM

Re: Experience installing portlights without fasteners?
 
Quote:

Originally Posted by KBuckley (Post 1045193)
I can't yet tell you how they will last but I just replaced all 8 windows on my '81 Yamaha 30 - just DC 795 surface mount - no fasteners. I followed the advice posted by Maine Sail here (http://www.sailnet.com/forums/1000233-post16.html) and followed the Dow Corning data sheet for DC 795. I purchased the 795 from my local glass shop as none of the marine stores in the area sell it. (!)

I was deterred from using SikaFlex 295UV by the data sheet recommendation that the joint be masked from sunlight to prevent degradation from UV.

I used rubber washers as spacers to ensure I had the bead thickness recommended for my window dimensions (6-8mm). DC 795 is cheap (<$10) for a 300 mL tube. Which is good because I used 20! I tried to get cast acrylic but in my tint it is apparently a custom run. My plastic supplier lead me to believe he had sourced it but when I unpacked the windows at the boat the material designation was for extruded. I complained but went ahead and installed it. I have 1 more week of curing to wait...then in a month, year, or a decade I will know how it worked!


Thanks a bunch! I appreciate that link to the Maine Sail post, that gives me a lot of confidence in this approach. I believe I will be using DC 795 now instead of the Sika (much cheaper and more recommended!).

Beersmith 07-29-2013 03:03 PM

Re: Experience installing portlights without fasteners?
 
finished the window project, thought I'd update anyone looking here:


http://www.thequestforwindandwaves.c...9-1024x768.jpg

full write up of the project here: Making and Installing Large Cabin Windows | The Quest for Wind and Waves


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