Fixed portlight install—foam tape spacers?

[Noah]

I took the leap this weekend and removed my fixed portlights. They were crazed, but not leaking but, couldn't help myself—the crazing just offended me—so I opted to replace them. New ones are being made at a local plastics shop, using old ones as a pattern. I have screws in mine which were easily removed and I will reuse them for install. The two forward windows came out in one piece. But not the aft ones. Due to a solid coating of sealant under them at the aft pillars (by the head) the aft ones snapped into multiply pieces. The first one rear one I removed resulted a big piece falling in the drink and the pillar section chiseled into small chucks. The second one I removed more carefully, resulting in  four intact pieces that I seamlessly pieced back together to use a suitable pattern. Both sides are symmetrical including the hole pattern fro the screws.
Now my question:
I have studied the Catalina instructions that call for 3/8-1/2 x 1/8 thick foam spacer every 6-8 inches to hold the window slightly off the fiberglass to prevent the 795 sealant from completely squeeze out when the window is pressed into place. BUT, doesn't that act as a barrier and eliminate any sealant from contacting/bonding the acrylic to the fiberglass where each foam spacer is located? Am I missing something here? When I removed the old windows, interestingly, despite what the Catalina shop drawing shows, there were no visible spacers underneath that I could see? Debating whether to use spacers or not? Thoughts please?

[glennd3]

Noah check this out.It may be applicable for you.
https://youtu.be/MQyjxVUskd8

[Noah]

Thx Glenn, I have seen that video. However, I am still opting for Dow 795 over VHB tape, due to historical success and our C34's windows that are bigger than Andy's, and harder to position. I just need to sort out the pros and cons of spacers.

[Stu Jackson]

When my portside fixed port started leaking when we were at anchor during our first winter (i.e., rain), when I removed it and rebedded with the silicone we had onboard, I do not recall any spacers.  I think your idea about using the 795 and no spacers is just fine, the screws have been holding mine in for 20 years! 

[glennd3]

Noah any chance of some pictures when finished?

[KWKloeber]

Oops [Glenn] NOAH:

Forgive my ignorance on your windows. You're talking about plexi windows that were siliconed on?  If so

Yes. Defo 795 it's tenacious and has the best adhesion property and the best elongation before failure property.
1) you don't need screws and many leave them off.
2) IIRC the blocks are partial, ie the 795 seals "outside" the blocks, which sit on the inboard edge.

IIRC becki did hers might be able to answer that.

I also know others who did them if you want to me to connect you up directly.

K

[Noah]

Ken- i sort of get what you are saying with spacers. If they are not as wide as the channel and were set close to the inner radius of the window, sealant would flow around outside edge.? Perhaps. I am happy with screws. The screws will help hold in window while sealant cures and makes it unnecessary to make some sort of jig or suction cups to press/hold in place. Pics. sealant yet to be removed. Cracked section during removal on pillar. Screw for sample depth. Old window before removal showing screws And my assistant. I am cleaning/scraping off old sealant this week.

[KWKloeber]

The CTY drawing shows that the small spacer blocks are way smaller than the total mating/sealing surface and are on the inboard edge, not affecting the 795 that's beyond (outside) the small blocks.

[karista]

Noah!

My fixed port side large port developed a small crack at one of the screw holes. Made a pattern and took it to Catalina Yachts in Largo, not far from where I live. They used my pattern and fabricated me a new replacement port, but refused to add the holes. They said that the holes are a source of problems when the screws are tightened a little too much and are totally unnecessary when using the Dow Adhesive.
So if you have the holes drilled be careful not too over tighten the screws.

[KWKloeber]

Noah

Along that line, many of the C-30ers who do use screws, they are temporary, remove them and fill the holes w/795. YBYC.

[Noah]

Thx for info Bernie. The screws were very easy to take out when removing old windows and I will be very careful not to over-tighten them when I install the new windows. Been raining here for two days (go figure!?!) but today I start removing old sealant and prepping surfaces for new.

[oldcatsailor]

Nosh i got my fixed Windows from Catalina their supplier had the orig. Specs. I didn't use spacers but per advice used 795 with weights hanging on the Windows with screws not fully tightened no leaks 5years.

[Noah]

The old sealant cleans off pretty easy/quickly and effectively with a sharp paint scraper used carefully.  Not my favorite job for a guy with an artificial knee  Next comes sanding.

[KWKloeber]

Noah be thankful they didn't use 795 originally - you'd be going in for a new shoulder 😳 as well.
That looks a mess but it will sure be worth the effort whence you get'erdone.
I can't wait to see the new ones.

[sailr4]

I just replaced one of mine last fall.  Used VHB tape with 795 around edge.  My glass shop would not bevel the edge like the original, but I think that actually helped to get more 795 in the gap.  No screws. i had the port side window made too, but will save that for another day (it's cracked but not leaking).

Rob