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Discussion Starter #1
The two 24 x 6 deadlights in my 1977 Mirage 24 need to be rebeded/replaced. I removed 14 screws that hold the exterior aluminum frame in place hoping that it would easily separated from the fiberglass. It did not. It appears that the plastic was set into a rubber frame (similar to an auto windshield) which also forms a gasket between the frame and cabin top.
Are new rubber gaskets or repair kits available?
Will I have to buy new deadlights with all the trimmings?
-CH
 

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Best way to remove deadlights (or port light frames, etc.) without totally destroying the 'gaskets' is to use ~20 gauge WOUND wire used on stringed musical instruments.
The winding over the core of the musical string produces a fine but regular rough surface. Use the wound musical string to SAW between the deadlight frame and surface that holds the deadlight in place .... SAW back and forth with the wound wire as close as possible to the 'surface' .

To reinstall, reuse the OEM gasket if you haven't totally destroyed it; Of if you did destroy the gasket go to GRAINGER or other industrial supply (also on the internet) and buy some 50 to 70 durometer (a measure of rubber 'softness/hardness') rubber sheet and cut your own gaskets. Use a compatible caulk, such as stretched-out Butyl-tape to complete the seal.
 

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Discussion Starter #3
Thanks Rich. I don't know if the OEM gaskets are worth saving except as patterns.
I'll use a string from my old Stratocaster Sunburst which hasn't seen the light of day for nearly four decades.
What the heck, if I sell the guitar I could put in 10-20 new portlights!
-CH
 

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Being one of the earliest Mirages, I am not sure just exactly what your frames look like. It would be good to see a close up picture before suggesting anything. From your description, it sounds like they were different from later Mirages and rubber gasket was a moulded piece?

Later Mirages as well as C&Cs, Tanzers and many Canadian boats had an aluminum frame with wide thin external flange. There was usually a rubber adhesive/sealant between the frame and the deckhouse or perhaps a soft butyl rubber tape gasket. IF yours are like that, repair may be easier.
 

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Discussion Starter #5
Being one of the earliest Mirages, I am not sure just exactly what your frames look like. It would be good to see a close up picture before suggesting anything. From your description, it sounds like they were different from later Mirages and rubber gasket was a moulded piece?

Later Mirages as well as C&Cs, Tanzers and many Canadian boats had an aluminum frame with wide thin external flange. There was usually a rubber adhesive/sealant between the frame and the deckhouse or perhaps a soft butyl rubber tape gasket. IF yours are like that, repair may be easier.
The deadlights do have a wide (approx. one inch) aluminum frame on the outside with 14 short screws that thread into the cabin sides. I see nothing inside except the headliner.
The following is conjecture based on external observation only:
It appears the frame may hold a slotted rubber gasket with the window in the slot. The plastic dimensions look equal to or smaller than the opening. A flange on the rubber gasket appears to be squeezed between the frame and cabin side. I'll take pictures this week and post.
-CH
 

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This is a portlite out of a Tanzer. Mirage and others used something similar.



If yours are like that, this write up might help.

Portlight Restoration

However, having done this a number of times, I have given up on using the splines. Used Dow Corning 795 filet to replace splines - One of few sealants that stick to aluminum and Acrylic. It is a commercial product used in hi-rise buildings, but also by Catalina to glue on their external windows. Had it in place for several years now and finally have long lasting leak proof ports!
 

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Windshield gaskets usually have a round beading strip installed in its own groove after the glass is slipped in.This firms up the completed gasket and puts pressure on the cabin side and the deadlite. If yours is built like that (may not be too obvious) just work the O strip free and pull it out.
 

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Yes, the deadlights on my Mirage look exactly like this. I like the sharpened putty knife approach. I must tackle this project soon.
-CH
Good winter job if you don't want to miss summer sailing!

When you get to it, maybe some of this will help:

Rebuilding aluminum frame portlites:
First step is to get the portlite off the deckhouse.
Then clean up frames and replace the seal for the plexiglas panes.
Probably best to cut new panes, perhaps slightly thicker unless you use spacers at inner side of frame.

Originally, a butyl rubber strip was used on the inside face of the frame, then the pane pushed into that. But it tended to soften in sun and oozed out! There were sometimes small spacers placed within the butyl to keep the outer spline tight, but more often the pane was not held as tightly and eventually leaked.

Once the pane is in place, the rubber spline is fitted. It doesn't go under the aluminum frame, it just fits into a groove in the frame. The frames with newly sealed panes are then fitted to deckhouse with sealant. Lifeseal would probably work. You want something that CAN be removed down the road.

Instead of the butyl rubber, I used 2-sided VHB mounting tape on inner face of frame - Kind of thing they sell at auto parts stores and even hardware stores for adhering trim or house numbers etc. I put strips of that in first in several places to act as spacers. I could only find it in large expensive rolls for size I wanted, but eventually found some from Hong Kong on eBay in shorter lengths.
Then applied a bead of 795 all around edge and pushed the pane into place (filling small gap around the edge between pane and frame). Once in place, I carefully created a bead something like the original rubber spline all the way around on the outside. I had first masked the panes to where I wanted the bead to end. Used wet finger to make a neat bead. Once set, used Xacto knife & straightedge to trim just inside the masking tape which was then removed. Wish I had kept pictures. Easier than it sounds!

If you took the removed portlites to a window shop that uses the 795 sealant, they may put in new panes for you at reasonable cost rather than buy more sealant and tape than you can use. It is used for windows in hi-rise construction, and even for windows in large aquariums.

The grey rubber spline is available for several makes of boats (Tanzer, CS, C&C) , but I found that they were all slightly different and before long fell out. Will never use splines again!

This video is install in a fibreglass deck frame, but I see he too also used vb tape and 795.

One other thought. Some owners (including me) abandoned the original portlites and installed external plexiglas . These were held in place with a sealant (795 would be best) plus a number of through bolts or screws. Screw holes must be a bit oversize to allow for differential expansion otherwise cracking will occur. Something like this guy did, using 795 and oversize holes.
 

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A thought...

VHB tape is the bees knees...if you use the right type. There are different types, so learn which will work best. It's in all the bog box stores...but not for all applications.

You would need that guitar string to remove it....but will probably never need to.
 

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A thought...

VHB tape is the bees knees...if you use the right type. There are different types, so learn which will work best. It's in all the bog box stores...but not for all applications.

You would need that guitar string to remove it....but will probably never need to.
Here in Canada, I didn't find much in the box stores. The lip on these aluminum ports is quite narrow and I think I wanted tape about 3/8 wide and thick enough (1mm?) to act as spacer. I found it in smaller quantities on eBay (from Hong Kong!) In US, even Walmart may have it! Certainly car parts stores.
 

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Discussion Starter #12
It has been suggested that I use 3m 4000 to bed the plexi into the frame and against the cabin. I also have considered using 3m Marine silicone.
Any comments or suggestions?
-CH
 

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It has been suggested that I use 3m 4000 to bed the plexi into the frame and against the cabin. I also have considered using 3m Marine silicone.
Any comments or suggestions?
-CH
The 4000 would be fine for bedding the aluminum frame to the cabin wall. But it is not suitable for adhering the acrylic pane to the aluminum frame. Silicone isn't a good adhesive at all. Believe me, I have been though this many times on Mirages, Kirby's, Tanzers.

The Dow 795 is by far the best for the setting the panes into the frames. You likely would have to get that from a commercial window company. The other possibility is Sikaflex 295 which is stocked by marine stores. You could use the 795 or the 295 for setting the frames into the cabin, but the 4000 would be better if you ever want to get them off again!
 

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Discussion Starter #14
795 it is! (Or, will be.) for bedding the plastic into the frames.

If I use 3m 4000 for bedding the frames to the cabin should I use spacers so the bead remains thicker to allow for movement?
-CH
 

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795 it is! (Or, will be.) for bedding the plastic into the frames.

If I use 3m 4000 for bedding the frames to the cabin should I use spacers so the bead remains thicker to allow for movement?
-CH
You may need to use spacers when inserting the panes into the frames. They originally may have had thin plastic spacers (or on earlier boats, butyl tape) on the inside of the panes (that oozed out and and left the panes loose)! That is where I used VHB tape about 1/16" thick. Do a trial fit of the panes. I increased thickness of the panes so that exterior caulk would look about same as original rubber splines. With even thicker panes, the spacers wouldn't be required. Just a thin layer of 795 or 295.

I don't think there is any reason to add spacers between frame and cabin top. I did mount my ports using butyl tape. It's about 1/8" thick but the screws compress it. I ran a bead of sealant around the exterior of the tape 9it was not full width of the aluminum port flange. Some of this oozed out, but was easily cut away once cured.

Hope this is understandable. Easier to do than describe! The key was getting rid of those rubber splines - The 795 does a great job.
 

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Discussion Starter #16
JOB DONE!
It was not as difficult as I first imagined and with good advice from contributors it looks great!

Used a putty knife to carefully separate the frame from the cabin. I think they were bedded in butyl.
The plexi pushed out of the frame with no effort. The old gaskets fell apart.
Sanded the frame contact surfaces with 120 grit sandpaper.
Buffed the plexi faces by hand the with 1000 and 2000 grit Aqua Buff compound.
Sanded the faces of the plexi around the perimeter about 1/4 inch from the edges with 600 grit wet or dry.
Laid the frames on a flat hard surface.
Squirted a small bead of 795 around the frame where the plexi seats.
Inserted the plexi into the frame.
Squirted another bead of 795 around the perimeter on the outside surface of the plexi.
Put weights on the plexi and waited for the 795 to dry. The 795 shrunk into a nice fillet.
Sanded the gel coat on the cabin sides where the frame seats with 120 grit sandpaper.
Squirted a bead of 4000 on the cabin side.
Screwed the frame in place.
I added more 795 around the perimeter of the plexi and formed about a 3/16 R fillet.
-CH
 

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Discussion Starter #18
Funny how sillycone is considered the bane of all marine sealants and Dow 795 is suggested for deadlight mounting in AL frames. 795 is a silicone sealant! I used it anyway. Can't leak any worse than before if it doesn't hold for a year.
-CH
 

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For you frugal guys, check out the dumpster at any auto body shop. They turf out partial rolls of all kinds of window sealant stuff. Keeps well so you can stash until date needed.
 

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Funny how sillycone is considered the bane of all marine sealants and Dow 795 is suggested for deadlight mounting in AL frames. 795 is a silicone sealant! I used it anyway. Can't leak any worse than before if it doesn't hold for a year.
-CH
Chas - Silicone is kind of a generic name for a family of sealants and adhesives. They are not created equal! The product sold as Marine Silicone is not the same as bathroom silicone and definitely not same as Dow's 795 which is a structural adhesive.

795 adheres to acrylic and other plastics as well as to aluminum and glass. Marine silicone does not. Don't worry about your 795 not lasting long. My ports have been in for 3 or 4 years and still are 100% good. So much better than those crappy rubber splines so many boat ports have.
 
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