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Looking for Advice on Fixed Portal & Headliner Replacement

Oct 9, 2013
68
Beneteau First 38 Belmont Harbor
Hi,

We are in the process of replacing the 29 year old plexiglas portals in our Beneteau First 38. While we are at it we are also removing the sagging foam backed headliner.

So far we have accomplished the following:

- removed plexiglas
- removed still soft (after 29 years) sealant which was used to seal the plexiglas to the outside of the deck, perhaps it was butyl tape?
- removed the inside aluminum frames
- cleaned all sealant residue from the deck and the interior
- dropped off old Plexiglas at local plastic fabricator as pattern for cutting/fabrication of replacements
- dropped off old aluminum frames at local shop for cleaning and re-anodization

While we are at it we have removed the cabinets & cooktop in the galley and the cabinets in the head to remove the sagging headliner that was also used there. The headliner extended from the ceiling and then to the backside of the cabinets.

We have new plexiglas being cut/fabricated and have sent out the aluminum frames for cleaning and reanodization. We also considered using polycarbonate (e.g., LEXAN) but chose to stay with plexiglas since it is less prone to scratching/hazing.

We had considered having new 316SS frames custom made for the inside but lost interest when quotes came back totaling near $1600. We will be using new foam headliner sold by Sailrite.

We ripped down the sagging headliner and then used a steel brush on a drill to grind off the old foam backing and the original glue. Big messy job. We had to keep the brush moving so that we would not heat up the foam/glue and create a bigger mess. Next step was to use heavy duty citrus cleaner (ZEP brand from Home Depot) which does contain MEA (MonoEthanolAmine) which is a good solvent. We then followed up with acetone. The fiberglass is now clean and no longer tacky from the old foam/glue.

We are unsure how we want to reattach the new plexiglas to the deck. Options are butyl tape (we have 2 new rolls from Maine Sail), DOW Corning 795, DOW 4200, or ??? Also, there will be a bunch (80+?) barrel bolts (aka Chicago bolt or sexbolt) which go through the plexiglas, the deck, and the interior aluminum frame.

Any suggestions on sealant to use? Any other hints & instructions?


Doug in Lakeview
1984 Beneteau First 38 – Hull #178
Belmont Harbor – Chicago
 

Attachments

Nov 26, 2008
1,879
Endeavour 42 Cruisin
You said the plexi will be held in place by the bolts, right?
Then sealant will be all that is necessary, not an adhesive. The caulks are adhesives and the butyl is a sealant. Let the bolts do the adhering and the butyl will seal the water out.
If there are no fasteners holding the glass in place then Dow 795 is appropriate.
 
Nov 9, 2012
2,435
Oday 192 Lake Nockamixon
Re: Looking for Advice on Fixed Portal & Headliner Replaceme

I dunno if I agree with that. If there is an aluminum frame for the bolts to pull against, thus distributing force across the plexi, MaineSail's butyl may be ok. But it really needs compression in order to seal properly, and point loaded fasteners drilled through plexi will not get the job done. I know that on my surface mount plexi windows, there is no frame around the outside. The original screws drilled through the plexi were just there to hold the plexi in place while the Dow Corning 795 cured.

To replace mine, I followed this article from Sail magazine: http://www.sailmagazine.com/boatworks/replacing-fixed-portlights They say that the 795 is preferred due to expansion/contraction differences between plexi and fiberglass.

You will need to sand the fiberglass surface where the old 795 sealant was applied in order to remove the silicone contaminated gelcoat. You should probably vacuum the sanding dust as you do it, so as not to grind in silicone contamination elsewhere. Nothing will stick to silicone contaminated gelcoat, including more 795.
 
Oct 9, 2013
68
Beneteau First 38 Belmont Harbor
Hi sailors,

We have received the new plexiglas portals back from the fabricator and have meticulously cleaned both the exterior and the interior of the openings on the boat. We are planning on attaching the surface mounted portals per procedure “Replacing Fixed Portlights” by Don Casey published in Sail Magazine. Thanks , Brian S, for providing the link to the article.

However, we have a couple of questions:

The 3M tape is grey and the Dow 795 sealant is available in 3 colors – white, black, & grey. To hide these from the exterior we are planning to paint the plexiglas surface so that the 3M tape and Dow 795 sealant are not visible. After installation, the tape & sealant will not be visible through the plexiglas and only a thin line of sealant will be visible at the plexiglas/fiberglass joint. We will be using the black sealant.

We only want to do this once and hope it lasts for many years. The original portals were also held in place with internal aluminum frames and “sexbolts” every 5 inches or so. We are not planning on using the “sexbolts” this time. We are hoping that the 3M tape and the Dow Corning 795 adhesive are sufficient to firmly attach and seal the portals – without the “sexbolts”. This will result in a much cleaner appearance. If the 3M tape and the Dow Corning 795 adhesive do not work (without the sexbolts) we may be repeating this a 2nd time – with sexbolts.

Does anyone have any words of wisdom? Are we making a mistake?

Our proposed procedure:

• Dry fit the portals on the exterior of the cabin and trace the window opening from the inside
• Use an exacto knife to cut through the film (which protects the plexiglas)
• Remove the ring of film where the adhesive tape & sealant will be applied
• The width of the sealing surface on our portals is 1 inch. The inner portion will be used for the 3M tape & the outer portion will be filled with the Dow Corning sealant.
• Paint the exposed plexiglas with black, silicon based high temperature paint.
• Allow paint to fully dry
• Apply the 3M tape (1/2” width) to the inner portion of the exposed plexiglas
• Reclean the fiberglass with isopropyl alcohol/water mixture
• Remove the film from the tape and carefully position the portals and apply pressure to attach it to the fiberglass
• The plexiglas is now adhered to the deck
• Apply masking tape to the deck around the perimeter of the portal
• Apply Dow Corning 795 Silicone sealant to the outer perimeter of the plexiglas insuring that the sealant is forced into the 1/10 inch gap between the deck and the plexiglas.
• Finish the edge of caulked joint
• Allow to set up and then remove masking tape



Doug in Lakeview
1984 Beneteau First 38 – Hull #178
Belmont Harbor – Chicago
 
Jan 22, 2008
7,076
Beneteau 323 Annapolis MD
Re: Looking for Advice on Fixed Portal & Headliner Replaceme

I know nothing about painting plexiglass, but can't help wondering how often you'll have to paint it? My 8-year-old Beneteau's paint rings are wearing off. I wonder if you might be better served by sanding the plexiglass rings so you can't see through it- and never have to paint it? I've done this with my storm windows so people can't see through my street-level 3x3 foot windows. As a side benefit, the treated windows act like a lens and actually make the room brighter!
 
Sep 28, 2008
922
Canadian Sailcraft CS27 Victoria B.C.
He will only have to paint the plexiglass once. It is only being painted under the part that overlaps the cabin side - it is done so the tape and 795 are not visible.
 
Oct 9, 2013
68
Beneteau First 38 Belmont Harbor
Ron,

The painted side of the plexiglas will be the underside - the side where the 3M tape & Dow Corning 795 sealant will be contacting the plexiglas. So I will only be able to paint it 1 time - before installing. Biggest concern is if the paint will tightly grip the plexiglas.

Your comment to sand the plexiglas to make it opaque is a good idea. This would also probably help to get better adhesion of the paint to the plexiglas if I sanded the underside.

The idea to paint the back side of the plexiglas is similar to what auto manufacturers do on SUVs, etc. They don't want the underside edges of a large sheet of glass - where the glass is glued to the vehicle - to show.

Doug in Lakeview
1984 Beneteau First 38 – Hull #178
Belmont Harbor – Chicago
 
Jan 22, 2008
7,076
Beneteau 323 Annapolis MD
...Your comment to sand the plexiglas to make it opaque is a good idea. This would also probably help to get better adhesion of the paint to the plexiglas if I sanded the underside.

Scuffing the plexi should make it so you would not see through it- same as paint, but adhesion is a side benefit.
 
Sep 28, 2008
922
Canadian Sailcraft CS27 Victoria B.C.
I think the tape will stick better to smooth plexiglass than sanded plexiglass.
 
Oct 9, 2013
68
Beneteau First 38 Belmont Harbor
Hi all,

A couple of fellow sailors have asked about our experience with our replacement of the fixed portals on our 1984 Beneteau First 38. Thus an update to the old thread.

We did the work prior to launch in 2014. We essentially followed the procedure “Replacing Fixed Portlights” by Don Casey published in Sail Magazine.

http://www.sailmagazine.com/diy/ask-sail/replacing-fixed-portlights/

Here is a link to pics of the process:

https://1drv.ms/f/s!AhBeqWheWY5jhl1fqgEyIulNOy74

The original portlights were held in place with internal aluminum frames, “sexbolts” every 5 inches or so, and sealant/adhesive. We did not re-use the internal aluminum frame nor did we use any “sexbolts”. Thus we are relying on the Dow Corning 795 Silicone sealant/adhesive to hold the portals in place. Dow Corning 795 is used for windows in high rise buildings. Great adhesion that remains a bit flexible after curing. So far the plexiglass has not leaked nor has it detached from the gelcoat. Currently, we are only sailing in the Great Lakes. If we were offshore we would consider putting in the “sexbolts” for additional strength/safety.

If we were to redo this, we would make the windows approximately 1 inch larger on all sides. This would give additional surface area for the adhesive and would cover scratches on the white gelcoat made by prior owner when he dug out old adhesive and then caulked with silicone.

Our procedure:

Dry fit the portals on the exterior of the cabin and trace the window opening from the inside

Use an exacto knife to cut through the film (which protects the plexiglas)

Remove the ring of film where the adhesive tape & sealant will be applied

The width of the sealing surface on our portals is 1 inch. The inner portion will be used for the 3M tape & the outer portion will be filled with the Dow Corning sealant.

Paint the exposed plexiglas with black, silicon based high temperature paint.

Allow paint to fully dry

Apply the 3M tape (1/2” width) to the inner portion of the exposed plexiglas

Reclean the fiberglass with isopropyl alcohol/water mixture

Remove the film from the tape and carefully position the portals and apply pressure to attach it to the fiberglass

The plexiglas is now adhered to the deck

Apply masking tape to the deck around the perimeter of the portal

Apply Dow Corning 795 Silicone sealant (we used black) to the outer perimeter of the plexiglas insuring that the sealant is forced into the 1/10 inch gap between the deck and the plexiglas.

Finish the edge of caulked joint

Use tape, sandbags, and/or long thin wood stakes (bendable) to hold the plexiglas in place for 3 or 4 days while the adhesive dries. This is especially important if there is any curvature to the portal.

Allow to set up and then remove masking tape.
 
Aug 3, 2012
2,518
Performance Cruising Telstar 28 302 Watkins Glen
You can scuff the back of the plexi to paint it black with regular flat black spray paint to hide the underlying white fiberglass. Leave the mask on the rest of the plexi. That is how we treat the plexi portlights on our 272. However, it is recommended that we remove the screws which fix the plexi in place for two reasons: 1. They are not structural once the Dow 795 dries. That adhesive is used to bond building panels weighing far more than our portlights! It will hold your portlights firmly to the side of your cabin. 2. Leaving the screws in will create a binding potential for the plexi as it expands and shrinks in the heat and cold. As an example, My 24" x 14" x 1/2" plexi swinging hatch doors expand over 1/8" on warm days. I have made a cover to protect them from heating up because I cannot remove all the screws from them given the need for hinges and a hasp. The screw holes in your portlights need to either be over drilled by 1/8 " to allow for movement, or the screws removed, and the holes filled with Dow 795 to seal them. If you do not overdrill the holes, and you leave the screws in, your plexi will craze, forming thousands of tiny cracks as the plexi presses against the screws. Likewise, your gelcoat arond the screws could get spider cracks from the pressure on the screws.
 
Sep 8, 2014
2,549
Catalina 22 Swing Keel San Diego
I'm doing the same job on my C-22, fabricated my own windows from tinted Lexan for less than $100. I'm also using Dow 795, 3M hi-bond tape, and no screws/bolts. I will also have to paint the backside of the overlap so you can't see the tape/adhesive through the lexan. Right now I'm not planning to use pain as I also have concerns about its bond strength. I will either brush on or knife on a very thin layer of the Dow 795 and let it fully cure before I mount the windows with the 3M tape. I'd like to thin it first, but I can get a good recommendation from anyone of what chemical works as a thinner for Dow 795, not even by calling Dow tech support. I have a 2 inch rubber roller to help set the 3M tape once the windows are in position.
I think leaving the screws out is the best idea. Also, having the 3M tape not only simplifies the install process, but maintains the standoff distance of the plexi/lexan away from the bonding surface so you get a nice, even film thickness of the 795. Bolts make it too easy to get too much squeeze out, resulting in in a 'thin' bond.
My only question to the OP, Doug, if you leave the bolts out how does the inner frame attach?

I'm probably a little late for this advice, but seriously, I'd leave the headliner off and just paint the ceiling. See all that green gunk in the pics before it was cleaned off? Headliners are a great place for moisture + dirt to hide and promotes mildew & mold growth. Plus, you can't easily get to any thru-deck hardware. JMO