Rex
This is a topic of MUCH discussion over the years. Suggest you check the photoalbum archives and you will get a lot of good information. We went the Sikaflex 295 route in 2006, followed the instructions to a “T” and no problems so far. Removing the old windows was a bear and involved a fair amount of gel coat damage which involved a lot of effort to repair. My thinking was I never wanted to go through that again so stayed away from the Plexus system. My research also indicated the adhesive industry had progressed a lot from when the boat was builtUsed ¼ inch rubber spacers to ensure sufficient depth of sealer. Drilled holes and used screws at each corner to hold in place while it cured (at least a week and is sensitive the heat and humidity). Removed the screws and filled with sealer. Be sure to well tape any adjoining surface as the sealer will squeeze out during installation and you do not want it to contact any adjoining surface as you will never get the black stain out. Checked my own archives and offer the following for your info. Hope this helps and best of luck John Maryann & others, Different strokes for different folks. I went the Sika 295 UV route. It was easy to work with, requires no special applicator and has a longer open time is easy to clean up afterwards and costs less. Make sure that you use it as directed. It must be used in conjunction with their cleaner and primer. The primer is formulated to form a tenacious bond with the acrylic and fiberglass (I specifically verified with their tech rep that it would also bond with epoxy, since that is what I used to repair and fair the window recess). The 295 UV polyurethane forms a tenacious bond to the primed surfaces. You will not get a good bond to the acrylic and fiberglass if you don't use the primer. The thing that convinced me to use this method was that after doing research on this list, it appears that after using the Plexus solution ther were people who didn't get it quite right and still had small leaks. They were so daunted and at the thought of breaking the plexus bond perhaps the acrylic and cost and hassle that none of them redid the repair. If you have to redo a Sika UV bonded window, it will be much easier. I don't really buy the structural argument either. My window just pushed out. It had surely not been structurally bonded for many years, but the cabintop has not collapsed, nor had I ever noticed it flex when walking on it and I am not a small guy. There is a general opinion on this list that you should almost never bond anything with 3m 5200 because almost every job will need to be redone at some point and if you used 5200 you are making it harder (if not impossible) to redo in the future. I apply this same philosophy to bonding the portlights. Don't do something that makes this almost impossible to redo. I have added a few pictures of the primer painted on to the window and recess to the [ http://www.user.firstclass.com/~eric/Arioso/Log%20Months/April%202005 ]April 2005 log page on my site. Here is an excerpy from the March 2005 log page which contains the details of some tips that the Sika Tech Rep. gave me. "I talked with Rick the Tech. Rep. from Sikaflex on the phone. He had the following advice about using the Sikaflex 295-UV system. The product numbers in Canada are different for some of the components. The Primer is 209N, the Cleaner is 205, The adhesive sealant is still 295-UV. The working time of the 295-UV is about 20 minutes.Try and make the bead about as deep as the mortise. Place the bead where it will meet the flat of the acrylic. Match sticks are fine as spacers. There are no problems in using this product with epoxy. When caulking the outside seam, push the caulking gun along, don't pull it. Smooth the seam with a gloved finger dipped in a bucket of water with about four drops of dish soap in it." -- Eric Haberfellner 1979 C&C 34 Arioso National Yacht Club Toronto Ontario, Canada 43° 37.9' N, 079° 24.4' W http://www.user.firstclass.com/~Eric/Arioso CnC Email List <cnc_l...@cnc-yachts.com> on Friday, January 27, 2006 at 10:28 PM -0500 wrote: >Different schools of thought - go the plexus route or the "soft" sealer >/ bond route?? > >Many on the list prefer the Plexus citing the added benefits of >structural bonding. I find that hard to accept as my boat and many >other C&C's in the area have replaced windows where the old ones were >not well bonded at all so not providing any structural strength and >with no apparent issues. Leaks, yes but no structure issues. > >Hunter, Sabre, Catalina, Tartan and C&C OEM as well as Select Plastics >all use one of three comparable "soft" sealer / bond systems > >1) Sika 295 UV - polyurethane sealant / adhesive (specifically >recommended by the "new" C&C for replacement of "older" C&C windows) >2) Dow Corning 795 - silicone building sealant >3) GE Silpruf SCS2000 - acrylic bonding agent > >The key for these is to prevent UV degradation. They all recommend >using window material that prevents UV light getting through, or to >paint the window exterior to prevent UV. I personally prefer the Sika >for its higher strength characteristics. > >Kind of like sealing an automobile windshield. Also have personal >experiences of several other C&C owners in the area - all with good >results using these sealers / adhesive. Let it flex, let it expand and >contract and all is well. You can still remove it if needed without an >act of Congress > >Cheers > >John & Maryann Read >Legacy III >1982 C&C 34 >Noank, CT > John and Maryann Legacy III 1982 C&C 34 Noank, CT From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Jim Watts via CnC-List Sent: Saturday, February 07, 2015 7:51 PM To: Rex & Jennifer Delay; 1 CnC List Subject: Re: Stus-List Window Installation - 1985 41 Do NOT use 5200. Here is one way to do it: http://www.cncphotoalbum.com/doityourself/portlight_replace/page01.htm Here is another way to do it: http://forums.sailinganarchy.com/index.php?showtopic=133986 <http://forums.sailinganarchy.com/index.php?showtopic=133986&hl=> &hl= Here's another way: Clean all traces of silicone from the window and frame. This will take roughly forever. I used a product I got from an auto parts store called "Acryl-Safe" which did a good job. You could also try any number of citrus-based silicone removers. Clean off all the remover residue with Interlux Special Thinner 216. You could try rebedding without screws. I opted to use screws on 6" centers, 4" would have been better. Drill the holes slightly oversize and use a washer under the screw head. The sealant is the next step. I used Life Seal (NOT Life Caulk!) because it has good adhesive qualities and does not interact with the acrylic/Lexan (whatever you have). If I was starting from scratch, I would use Sikaflex 295 UV with the special primer and skip the screws. Jim Watts Paradigm Shift C&C 35 Mk III Victoria, BC On 7 February 2015 at 16:18, Rex & Jennifer Delay via CnC-List <cnc-list@cnc-list.com> wrote: We have a relatively new to us 1985 41. The windows and hatches had been replaced by the previous owner. Hatches were done right, the side windows were bedded in silicone, not right. I had to re-bed one of them already but did not get all traces of the silicone off so it did not take. Need to do it again as soon as possible which will involve removing the window, scraping clean and then wiping the cabin side with acetone and re-bedding with 5200. The question is – there are no mechanical fastenings? Should I add screws every 4” or so or create some sort of method to press the windows in place while the 5200 sets? Anyone come up with the perfect jig to do this or is it better to add screws? Large custom bar clamps? Rex & Jennifer Delay www. Ghostlake.com <http://www.ghostlake.com/> www.ghostlakesailing.com _______________________________________________ Email address: CnC-List@cnc-list.com To change your list preferences, including unsubscribing -- go to the bottom of page at: http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com --- This email has been checked for viruses by Avast antivirus software. http://www.avast.com
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