Allen,
If I understand your question, I used Dow Corning 795 Black silicone.
Gary
~~~~~~~_/)~~~~~~
On Thu, Dec 3, 2015 at 7:46 PM, allen via CnC-List <[email protected]>
wrote:
> What did you use for caulking to protect the bond? My caulking is coming
> undone.
>
> Allen Miles
> s/v Septima
> C&C 30-2
> Hampton, VA
>
> *From:* Andrew Burton via CnC-List <[email protected]>
> *Sent:* Thursday, December 03, 2015 9:26 AM
> *To:* [email protected]
> *Cc:* Andrew Burton <[email protected]>
> *Subject:* Re: Stus-List Bonded Windows (continued)
>
> I have templates for the C&C 40 windows if anyone needs them. Actually,
> just a set of old windows the PO thoughtfully passed on to me.
>
> Andy
> C&C 40
> Peregrine
>
> On Thu, Dec 3, 2015 at 9:17 AM, Pete Shelquist via CnC-List <
> [email protected]> wrote:
>
>> Just an observation; The VHB tape seems like a more simple installation.
>> However, I’m curious if Plexus is evil because it’s too hard and tenacious,
>> yet the VHB joined parts won’t come apart, in 5-10 yrs when redoing windows
>> again it sounds like we’ll be calling VHB evil.
>>
>>
>>
>> I don’t have a better solution, and question if there’s really a good one
>> out there. It sounds like we need to keep templates of the lenses and deal
>> with cutting and filling around the frame when the connection fails.
>>
>>
>>
>>
>>
>>
>>
>> *From:* CnC-List [mailto:[email protected]] *On Behalf Of *Gary
>> Russell via CnC-List
>> *Sent:* Wednesday, December 02, 2015 7:47 PM
>> *To:* C&C List
>> *Cc:* Gary Russell
>> *Subject:* Stus-List Bonded Windows (continued)
>>
>>
>>
>> For those who were following my post on bonded windows on High
>> Maintenance, I have an update and many thoughts on the project enumerated
>> below. I have successfully installed two windows on the starboard side and
>> replaced the acrylic on all the hatches and can say that the project has
>> been very successful. I have terminated my project at this point as the
>> temperatures are now too low for the VHB tape which requires a temperature
>> of greater than 60 degrees F for application. Here are my observations:
>>
>>
>>
>> #1. Plexus is evil stuff and should not be allowed on a boat. It is too
>> hard and tenacious a bond. Because fiberglass and acrylic have such a
>> different expansion coefficient, fracture of the acrylic is assured.
>> Removing the stuff is impossible without destroying the gel coat
>> underneath. I tried a sharp blade between the fiberglass and the acrylic
>> and all I managed to do was rip up the gel coat.
>>
>>
>>
>> #2. Before removing the windows, make a template out of some thin
>> plywood (or other material) because the window will (no doubt) come out in
>> pieces and you will have nothing as a reference for making the new windows.
>>
>>
>>
>> #3. I finally was successful removing the acrylic with a 5/8” router bit
>> set to a depth equal to the thickness of the acrylic plus the thickness of
>> the Plexus. I actually used a Roto-Zip instead of a router as it had a
>> smaller footprint and was easier to handle. I free-handed the router to
>> cut through the acrylic and into the Plexus. It’s risky but effective.
>> Don’t cut all the way around the perimeter, but leave tabs to support the
>> window. Otherwise, the window will sink under the weight of the router and
>> you will cut into the gel coat. You can break out the tabs later.
>>
>>
>>
>> #4. Once the windows were out, I used West System epoxy thickened with
>> low density filler to repair any damage to the gel coat. Fortunately, all
>> my gel coat damage was limited to the area under the windows. Once the
>> windows are out and the damage is repaired, the rest is fun and easy.
>>
>>
>>
>> #5. I cut the new window out of 3/8” Plexiglas using a pattern router
>> bit (sometimes called a Formica trimmer). I used masking tape folded in
>> half lengthwise to stick the new Plexiglas to the old window (or
>> template). I ran the tape at right angles to insure that they wouldn’t
>> slide in either direction with respect to each other. It does a very nice
>> job and is quite easy. I then used a 1/8” round off router bit on the
>> outside edge of the new window for cosmetic reasons and a 45 degree chamfer
>> bit on the inside edge to make room for the Dow Corning 795 silicone.
>>
>>
>>
>> #6. I installed the 3M VHB 4991 tape on the coach roof and masked around
>> where I wanted the window to go. This would help me locate the window and
>> provide the masking for the Dow Corning 795 silicone to follow. I also
>> masked the edge of the new window for the same reason.
>>
>>
>>
>> #7. Now cones the tricky part. You only get one shot with the VHB tape,
>> because once it is down, it is not coming up. I tried adhering two small
>> pieces of acrylic to each other with about two square inches of VHB tape,
>> and I can assure you, you won’t pull them apart. VHB is amazing stuff. As
>> a guide, I mounted two small wooden blocks to the masking take below the
>> window with a small piece of VHB tape. By attaching it to the masking
>> tape, I was sure I could get it back off. Actually, VHB doesn’t stick very
>> well to masking tape anyway. I also stuck a small wooden block to the
>> masking tape at one end of the window as well. This allowed me to set the
>> window on the two bottom block and then slide it over to the end block
>> before pushing the window into place. By all means, make several trial
>> runs with the film still on the VHB tape before removing the film. Once
>> the film is off you are committed. I pushed the window in place and it
>> looked perfect. Then it is simply a matter of squirting the Dow Corning
>> stuff into the gap and smoothing it out with a finger. As soon as the
>> silicon is smoothed out, you can remove the masking tape and pour yourself
>> a stiff one, while you admire the fine job you have done.
>>
>>
>>
>> #8. There was concern expressed that the VHB tape would be visible
>> through the window, and it was suggested that the window should be painted
>> with Krylon Fusion Black. Actually, the VHB tape is the same color as the
>> Plexus which is not visible, so the VHB won’t be visible either. No paint
>> is necessary. I used the darker shade of grey Plexiglas and can say that
>> it look spectacular. The darker shade really “pops” and the contrast is
>> particularly attractive (in my humble opinion). The darker color makes it
>> difficult to see into the boat, but has a minimal effect when looking out.
>> The VHB is not visible at all.
>>
>>
>>
>> #9. There was also concern expressed concerning whether the curvature of
>> the coach roof would cause a flexing force to peel the VHB tape. I can say
>> that the radius of curvature is very large (>20 feet) and the forces are
>> thus very small. 3/8” acrylic over those lengths is quite flexible. I see
>> no problem at all.
>>
>>
>>
>> #9. I have posted some pictures on Google Drive and I think you can view
>> them at:
>>
>>
>>
>>
>> https://drive.google.com/folderview?id=0BwQRSP2fYIFmemxYOGlVcHNUNVk&usp=sharing
>>
>>
>>
>> I am new to posting pictures, so if you have trouble seeing them, email
>> me and we can get it fixed. I will add more pictures as they become
>> available.
>>
>>
>>
>> #10. Needless to say, I am thrilled with the outcome so far. I have
>> also re-glazed the hatches using the Boatworks video and they came out
>> spectacular as well. The only difference I made from their recommendations
>> is that I bedded the acrylic in butyl tape instead of the Dow Corning 795
>> because it was much easier to get a uniform bead and that was the way it
>> was done from the factory. I still filled the gap around the windows with
>> the Dow Corning 795. Boatworks is right, the Dow Corning 795 is nice stuff.
>>
>>
>>
>> #11. If I have left anything out or you have any questions about this
>> post, just give me a shout.
>>
>>
>>
>> Gary
>>
>> S/V High Maintenance
>>
>> ’90 C&C 37 Plus
>>
>> East Greenwich, RI, USA
>>
>> ~~~~~~~_/)~~~~~~
>>
>> _______________________________________________
>>
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>>
>>
>>
>
>
> --
> Andrew Burton
> 61 W Narragansett Ave
> Newport, RI
> USA 02840
> http://sites.google.com/site/andrewburtonyachtservices/
> phone +401 965 5260
>
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