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Replace acrylic portlights

Discussion in 'Catalina 22' started by kbgunn, Oct 12, 2017 at 11:27 AM. Add this thread to a FAQ

  1. kbgunn

    kbgunn

    Joined Sep 19, 2017
    12 posts, 2 likes
    Catalina 22 Gen 2 WK
    US texas Lake Lewisville
    I finally decided to address the acrylic windows that were sun damaged, crazed and leaking.

    Outside-
    [​IMG]

    Inside-
    [​IMG]

    Several people recommended this resource from sail magazine: https://www.sailmagazine.com/diy/replacing-fixed-portlights
    This youtube video seems like a independent validation:

    So I dived in with irrational exuberance. After removing screws and running the putty knife around the seal from the inside, the acrylic pops off easy enough.
    [​IMG]

    I dropped the old acrylic off at the local plastics fabrication shop to match the thickness, shape and bevel. I now turn my attention to surface prep while waiting on the new material. Does anyone have a quick and easy way to remove the old silicone based bedding material and get a proper surface for the 3M VHB (very high bond) tape to adhere? Also for the Dow Corning 795 sealant to stick.

    I've thought of razor blade scrapers, wire wheel in a drill, 3M scrubber pad, repeated application of mineral spirits, and swearing. All of these seem like grueling work with questionable results. Any suggestions to get it done in an hour's time would be greatly appreciated. Also, any tips for installing the new material efficiently would be welcomed. Wind forecast for Saturday is 10-15 kts and I'd rather be sailing then scraping. B-)
    KBG
     


  2. rpludwig

    rpludwig

    Joined May 23, 2016
    283 posts, 105 likes
    Catalina 22 #12502
    US New Bern, NC BSC
    from my limited experience you're on the right track...razor blade scraper, swearing works, add a thin putty knife, and a wide thin flat blade screwdriver to the equation...no eze way, but the results are worth the effort...others know better & will chime in....(silicone doesn't belong on a boat imo)...
     


    greg_m likes this.
  3. Bill Roosa

    Bill Roosa

    Joined Jun 6, 2006
    6,859 posts, 99 likes
    Hunter 40.5
    US Harrington Harbor North, MD
    Goof Off
    Stuff is great at getting just about any kind of sealant off.
     


  4. SVMOONDANCE

    SVMOONDANCE

    Joined Aug 31, 2017
    44 posts, 21 likes
    Catalina Catalina 22
    US Tampa Tampa


  5. kloudie1

    kloudie1

    Joined Nov 6, 2006
    7,313 posts, 286 likes
    Hunter 34
    US Mandeville Louisiana
    Whatever you use, be sure to tape a cover over the interior opening so you can control the dust and keep the interior cleaner.
     


  6. kbgunn

    kbgunn

    Joined Sep 19, 2017
    12 posts, 2 likes
    Catalina 22 Gen 2 WK
    US texas Lake Lewisville


    SVMOONDANCE likes this.
  7. kbgunn

    kbgunn

    Joined Sep 19, 2017
    12 posts, 2 likes
    Catalina 22 Gen 2 WK
    US texas Lake Lewisville
    Excellent. That's thinking ahead. I would be wasting quality sailing time with the shop vac cleaning silicone debris out every nook and cranny.
     


  8. SVMOONDANCE

    SVMOONDANCE

    Joined Aug 31, 2017
    44 posts, 21 likes
    Catalina Catalina 22
    US Tampa Tampa
    Use it with a LIGHT touch! They are designed for removing gasket material from metal so be easy with it and don"t push hard, let the tool do the work. As soon as you see the gel coat underneath the caulk showing through move on.
     


  9. CloudDiver

    CloudDiver

    Joined Sep 8, 2014
    2,296 posts, 260 likes
    Catalina 22 Swing Keel
    US San Diego San Diego
    I did this job on my C22, it only cost me $100 to buy the plastic and I cut myself. I did use 3M VHB tape but I shot myself in the foot with the process I used; The pro's will paint the inside edge of the window black because usually VHB tape is grey and you would see the grey tape through the plastic. Mine is as dark of a tint as they have available in Lexan but you can still see through it. The black VHB tape Andy uses in the Boatworks Today video is only available in 3/4" or 1 inch, mine was only 3/8 wide and Grey. Anyway, I wasn't sure about what kind of paint to use and I wan't confident the paint would stick to the smooth Lexan. So I though I was smart and I knifed a very thin coat of the Dow 795 to the bonding lip of the window. This seemed like it was going to work great until I discovered that the 3M tape will not fully stick to the cured DOW 795! I had to think fast so I ended up using just a few screws that firmly held the window in place (still using the 3M VHB tape as a gasket to maintain spacing) and I caulked in the 795 around the outside edge and then also on the inside. When it was cured I took the screws out and put just a dot of 795 in to fill the holes, it came out fine and the 795 is doing all the work. Note, my 'bonding edge' or perimeter of surface contact was 1.25 inch all the way around. Kinda overkill, I should have done it only 1 inch, but it still looks good.
    Manually scrape off all the old silicone adhesive with a SHARP scraper, then sand. There are no common solvents that will dissolve cured silicone... not Acetone, not MEK, not Toluene, trust me. There is some stuff out there for that that DOW makes but its nasty and expensive plus I have no idea how it will react with gelcoat. A very thorough scraping followed by 80 grit sanding should get plenty clean for the VHB tape to stick very well. Don't worry about the 795, that stuff will stick to anything as long as its clean and dust free.
    windows.jpg
     


  10. greg_m

    greg_m

    Joined May 23, 2017
    170 posts, 47 likes
    Catalina Jaguar 22
    ZA Cape Town, South Africa Simons Town
    Some loud music + swearing + elbow grease = job done!
     


  11. greg_m

    greg_m

    Joined May 23, 2017
    170 posts, 47 likes
    Catalina Jaguar 22
    ZA Cape Town, South Africa Simons Town
    I found these items at my local hardware store. Thin brass wire brushes that mounted into the chuck of a rotary drill. Used carefully they make extreme short work of any rubber bonding/sealing compound. Use a variable speed drill to keep the revs low.

    Used not so carefully they will remove skin as well! Don't ask...
     

    Attached Files:



  12. Gene Neill

    Gene Neill

    Joined Sep 30, 2013
    1,970 posts, 470 likes
    Catalina 22, Albin Vega 27
    US central Florida
    Luke, were you able to maneuver the caulk tube around in the cabin to caulk the inside edges?

    The little forward windows on the Vega did not allow this, and I can't find Dow 795 in a small tube. Nor have I found an acceptable "extension tube". They may just remain uncaulked on the inside if I don't find something.
     


  13. CloudDiver

    CloudDiver

    Joined Sep 8, 2014
    2,296 posts, 260 likes
    Catalina 22 Swing Keel
    US San Diego San Diego
    I was able to move the gun around inside the C22. In the Vega, you could put the calk on a plastic board and knife it in. I had everything taped up and used a wet finger to smooth the bead. It wasn't the neatest job but it was effective (yet still messy).
     


  14. Mark Maulden

    Mark Maulden

    Joined Jan 25, 2011
    1,378 posts, 77 likes
    S2 11.0A
    US Anacortes, WA
    I'm going through this now with six windows. I'm finding that Debond dissolves Sika 295 very nicely. They claim it will dissolve 5200 et al..
     


  15. catalanc

    catalanc

    Joined Mar 23, 2015
    115 posts, 20 likes
    Catalina 22 MK-II
    US Dillon, CO
    On a separate thread, I have asked about removing an in hull transducer. One issue will be to remove the residual caulk/epoxy. These sound like they might work pretty well for that as well!
     


  16. Leeward Rail

    Leeward Rail

    Joined Mar 20, 2015
    1,199 posts, 182 likes
    Catalina 22 New Style
    CA Lake of the Woods
    We use them when removing gasket material and debris from surfaces when repairing intakes and doing head gaskets on motors (that don't require machining), rubber weather stripping glue, windshield install prep, etc etc.

    They work great for any gasket/silicone/rubber material. They are much more gentle that a wire wheel.
    They work great with aluminium and give a nice smooth finish if used correctly.
    The 3M bristle discs are available in multiple different abrasive grades (50, 80, 120) for different tasks.

    I have used them on fibreglass with great success.

    FWIW, there a multiple different type of discs that work with a roloc style mandrel.
    Sandpaper, bristles, scotchbrite surface prep, wool/polishing, you name it.

    You can switch from disc to disc, in 5 seconds without removing the mandrel from the chuck. I rarely, if ever, find a need to use my wire brushes since I've started using the roloc style products.
     


    Gene Neill likes this.

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