I re-did my windows using the VHB method this spring.

Removing the old windows with a sharp putty knife and a hammer was the hardest part.

Rough repair on the damaged areas with 2 part epoxy.  In retrospect I should have painted the blue repair closer to the deck colour since some edges are visible under my tinted plexi.

Cut the new windows from a full sheet of 3/8" plexi - that was a pain.  Jig saw cut the lines easily but I should have had a belt sander to straighten out my poor lines.  Router to round over edges.  Then used a torch to "polish" the edges.

Held the new windows in place and marked the inside paper surface.  Removed paper from outer portion that would contact hull.  Sprayed black Krylon Fusion plastic paint (couple coats) to help obscure the repaired area (glad I did that part as I can see through to the hull on certain angles).

Put VHB tape on the back of the window.  Got everything positioned and used the "masking tape" hinge method recommended by by another list member.  Worked very well.

My cabin has moderate curve and 2 long windows on each side - I didn't even need any bracing to hold the windows in place.  Once I pressed them on they were NOT moving (so better get the location right the first time!).  Followed up with masking off cabin sides around the windows, then Dow 745 equivalent to seal around the window rim. 

Zero leaks since and nice to have clear windows.

Mark


On 2017-11-22 10:17 AM, robert via CnC-List wrote:
Scott:

My boat has two windows on each side as well, and one, the long one has a significant curvature which puzzled me as to how I would keep it in place without a frame, screws, bolts etc.  I completed the job 8 years ago and the windows still look like new with no issues.

First, I removed the old windows using a stiff putty knife which I filed the edge very sharp and tapped on the inside of the window slowly and carefully with a rubber hammer to cut the old Plexus.

I cleaned the Plexus from the old windows as they were used as a template to cut the 4 new windows.

Where the old windows came out, you may find the Plexus lifted some of the gelcoat....you can fill and smooth over with a filler or just leave it as the adhesive will take care of it.

At the time, I was not aware of the VHB tape so I used Sika 295 UV and the Sika Primer......I can not stress enough the need to include the Sika Primer and it is more expensive that the Sika 295 UV which I used 2 tubes (not all of it but I needed some of the second tube).  The Sika 295 UV will not bond properly without the Sika Primer.

The new windows will have paper on both sides so you have to put them in the cabin sides and draw around the inside so the paper can be cut away where they fit into the cabin side.  With sand paper, rough up the new window where they will be mounted.

I taped both the inside and outside of the cabin......the Sika 295 UV is very dirty stuff....you will need a solvent and lots of rags handy.  I applied the Sika to both where the windows will be mounted, liberally as I wanted it to ooze out when I pushed the windows into place and some on the edge of each window itself.

I resorted to cutting 3 pieces of 2" X 4"'s approx 23" long for each window to brace it after applying the adhesive......I put the 3 pieces of wood against the window and braced them against the toerail placing a 10 pound rock on each piece of wood to ensure it stayed in place.....left the braces on for 48 hours to allow sufficient curing time with the moderate Spring temperature.

I did one window at a time, removing the tape inside and outside, before the adhesive started to cure.

If I were to do it again and was assured that the VHB tape would address the curvature issue with the wooden braces, I would use the VHB tape, regardless of cost.  While the Sika 295 UV and Sika Primer is effective, it is more labor intensive with the application and it is messy if you are not prepared.

Several years back I had to replace my car windshield and they used a Sika adhesive.....the people that did it said the Sika adhesive they used was similar to the one I used except the curing time was a fraction of the 295 UV for obvious reasons.....they don't want your vehicle in the shop for 24 to 48 hours while it cures.

Maybe the VHB tape and bracing will address your curvature.

Rob Abbott
AZURA
C&C 32 -84
Halifax, N.S.







On 2017-11-21 5:59 PM, Scott Baker via CnC-List wrote:

Hi All,

I am still really new in this group and I’ve not really figured out how to search through the archives to find the advice I need.

I know this topic has probably been exhausted on here, but I need to replace my portlights on my 1987 35MKIII.

Some background and my questions:

~My boat has 2 windows on each side, but they still have a slight curvature in them.

~I’ve watched Andy’s Youtube Video where he uses VHB (Very High Bond) Tape from 3M to install similar portlights. (although no curvature) https://www.youtube.com/watch?v=MQyjxVUskd8&index=2&list=PLV97GZkHhpHMFb660AAGO4PuRKJPmHxDS

~I like Andy’s install method but obviously I’m worried about the curvature issue. Can I induce curve into the windows before I mount them? If I brace them in place I fear they will pop back “flat” again later? Solutions?

~I’m afraid of using screws or through bolts in the mounting proceedures because of the expansion issues etc… Is this a stupid fear?

~I’ve done enough scoping around to learn that everyone seems to have a different opinion of what the best material is to make new windows out of. Andy points us towards a specific material and source on his website.

~I’d like my new windows to be tinted, it seems this would make it hard to see in and also hide the flange in case it gets mucked up… Yes?

~I cannot find a good explanation of the best method to remove the old windows.

~I think many use the old windows as templates to make the new ones… so therefore they must be removing them intact? Has anyone mastered the removal of these windows without hacking everything up?

~My boat is on the hard and inside a huge shed now in Upstate, NY… Do I need to wait until it’s really warm to do this? Maybe I work on removing the old windows and cleaning up the mounting areas and put new ones in in the spring?

Can someone point me in the right direction to find all the answers?

If there is a trick to locating past chats about all this on the C&C site, I’d love to be edumacated!

Sorry for beating this dead horse.

~Scott Baker

 



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