Kevin:
I intended using suction cups to hold my new windows in place, however,
before I actually did the job, I experimented with the suction cups on
the new windows and found they did not hold on for very long. I used
Sika 295 |||||||||||UV as the adhesive and therefore left the 'paper' on
the inside of the new window to keep the Sika off. The paper interfered
with the holding capacity of the suction cups and I had to go to plan B.
Plan B involved placing 2" X 4"'s from the toerail to the outside of the
new windows with approx. 10 to 15 pounds of weight on each piece of
wood......I think I used three pieces of wood on each of the front
(longer) windows and two on the back (shorter) ones.
I suggest you test the suction cups before you attempt the job.
Rob Abbott
AZURA
C&C 32 - 84
Halifax, N.S.
On 2015-02-18 1:08 AM, Kevin Driscoll via CnC-List wrote:
When I do this project I plan on using a glass suction cup or likely
two from the inside and tie them off somewhere under load. In my
opinion using these in tension while provide a much more even and
stronger load across the portlights, keeping them in place while they
cure. I prefer to keep my stantions for what they were intended,
keeping the lifelines in place for an emergency.
This:
http://m.grainger.com/mobile/product/FAST-CAP-Suction-Cup-Lifter-3KNF1
or similar product as was already mentioned.
On Tue, Feb 17, 2015, 8:40 PM Dr. Mark Bodnar via CnC-List
<cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>> wrote:
Robert,
Thanks for further input. My plan is to follow the same idea. I
like your keyhole idea to locate the window effectively.
One question - did you tape the window in place and then add the
795 into the gap? Or did you put some 795 on the back of the
acrylic (or the cabin side)? I feel like I'd like to get more 795
in begins the acrylic - but maybe the point is that the tape
provides the holding power and the 795 is just waterproofing sealant.
Mark
On February 17, 2015 2:22:57 PM AST, "Robert H. via CnC-List"
<cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>> wrote:
I am writing to update on my portlight replacement project.
The installation went perfectly and the portlight looks great.
Applying a few wood blocks to the inside of the portlight with
removable, double-sided poster tape was a very effective way
to affix the portlight in proper alignment. It slid into
position like a puzzle piece, which is good because you only
get one crack at it with the VHB tape.
I also have a very good feeling about the VHB / DC 795 method
- though time will be the ultimate judge. I am comforted by
the thought that the tape and DC 795 will allow the
portlight to expand and contract with heat and cold at a
different rate that the cabin top without breaking the bond
(in theory, anyway).
For those that are thinking of using the same technique,
here’s one final tip and a few comments.
The tip: I had good success using a couple of telescoping
hiking poles to apply pressure to the portlight by bracing
them against the lifelines while the VHB tape set up. I also
used a heat gun to warm up the cabin top before applying the
portlight.
I have no leaks in any of the other portlights (yet), so I’m
going to wait until the weather warms up before I start on
them. I learned that the initial bond of the VHB tape is
dependent on both the application of continuous pressure and
the ambient temperature. The 3M data sheet does a better job
of explaining this than I will. Once you have a solid bond,
it will hold well even in cold conditions, but you will be
doing yourself a favour if you wait for warmer conditions.
Sent from Windows Mail
*From:* RPH via CnC-List <mailto:cnc-list@cnc-list.com>
*Sent:* Sunday, February 15, 2015 9:06 AM
*To:* cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>
I have been reading the recent posts about windows and I
thought that some might be interested to hear of my experience
replacing the portlights on my 1989 30 MKII. Please note that
I just started the on-boat part of the project yesterday and
the work is not yet complete.
In late fall I made tracings of the portlights which I
transfered to 1/2 inch ply. The templates were cut using a
circular saw with a guide rail system and a router. I then
took my templates to a local plastics manufacturer, and they
made the portlights from 1/4 inch plexiglass (Bronze 2404).
The edges of the portlights are bevelled at 22.5 degrees (if I
remember correctly). They turned out to be very good
reproductions of the factory portlights.
To ready myself for the project, I also purchased 36 yards
of 3M VHB 4991 Tape 1/2" x 2.3mm, 4 tubes of Dow 795
structural adhesive (I chose white over black), and a can
of DEI 010301 Black High-Temperature Silicone Coating exhaust
paint.
Yesterday, I attended at the boat with a view to replacing
only the aft, starboard portlight (because I didn't want to
bite off more than I could chew). I knew that the factory
portlights were glued on with a methacrylate adhesive and that
they would be difficult to remove. I brought my Dremel
Multimax (which is like a Fein Multimaster) and tried using a
flexible scraper to get between the plexi and the cabin top.
This was not effective. In the end, I used several small putty
knives which easily removed the portlight.
What the putty knives did not remove was the remnants of the
methacrylate adhesive. I tried several different techniques to
remove the adhesive but ultimately decided that the better
course would be to fair the area with 3m Premium Marine Filler.
After sanding the fairing compound, I held the new portlight
in place while my wife traced the window opening from inside
the cabin onto the protective paper film. Then I used an
Exacto knife to cut the paper along the tracing and removed
the paper surrounding the window opening. Next, I spray
painted the inside of the portlight black with the DEI paint
so that the tape and Dow 795 will not be visible against the
cabin top.
I experimented with small pieces of the VHB tape and was
surpised to see that it did not seem to stick too well to the
cabin top even after the surface was carefully cleaned with
alcohol. I decided that the fairing compound should be left to
cure overnight and I will try again today. In any event, I
have since read that the VHB tape needs time to reach maximum
adhesion, and that it will adhere more quickly when the
temperature is warmer. I'll bring a heat gun today to warm up
the cabin top before applying the portlight.
Anyway, if all goes well, the plan is to first affix the VHB
tape to the inside of the portlight. Then, with the portlight
dry-fitted in place, I will affix a few wooden blocks to the
inside of the portlight (through the cabin top window opening)
using double sided poster tape. My hope is that I can then
remove the protective film from the other side of the VHB tape
and then fit the portlight into place like a "key" into a
keyhole. After the tape is set, I will then fill the gap
around the outside with the Dow 795.
That's the plan, anyway.
Robert H.
Email address:
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-- Dr. Mark Bodnar --
Bedford Chiropractic
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