Cracks in window frame. How to fix?

Discussion in 'Multihulls' started by mrybas, Mar 4, 2018.

  1. mrybas
    Joined: Jun 2017
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    mrybas Junior Member

    Hi,
    What would be the best way to fix cracks in window frames?
    I was thinking some carbon unis (blue tape) and framing the window with 1700 biax glass. Thoughts?
     

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  2. UpOnStands
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    UpOnStands Senior Member

    You filled the crack in photo #2?
     
  3. Ad Hoc
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    Ad Hoc Naval Architect

    Before you attempt to repair it, you need to establish why it cracked to begin with. Otherwise it'll suffer the same fate!

    The 3rd picture suggests poor fabrication, since there is a 'crack' or saw cut in the wood lining. It may be as simple as that. If not it could be the laminate thickness is insufficient for the loads the windows experience.
     
  4. mrybas
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    mrybas Junior Member

    No, this was a a repair by an old owner. I think he may have dremeled out the crack and filled it, but didn’t add any or much glass.
     
  5. mrybas
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    mrybas Junior Member

    The cracks do coincide with where two pieces of timber were joined together.
    (I apologize, the pictures posted sideways!)
     
  6. UpOnStands
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    UpOnStands Senior Member

    Thanks, thought that filler looked old. 4 corners, how many have cracks and which ones?
     
  7. mrybas
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    mrybas Junior Member

    Hi,
    Three corners have cracks.
    The largest crack is upper inboard corner. The crack is in the corner of the window frame and extents to where the post (vertical timber) meets the beam (horizontal timber).
    The upper outboard and lower outboard corners also have cracks. These crack are where the triangle wedge of the radius has separated from the vertical and horizontal sides of the window.
    Picture 1 general overview
    2 upper inboard corner of the window taken from cockpit
    3 upper outboard from cockpit
    4 upper outboard from cabin
    5 lower outboard from cabin

    6 and 7 there is the same window on the port side, but it only has a crack in the upper inboard corner
     

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  8. TANSL
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    TANSL Senior Member

    When an opening is made in a panel, it is always necessary to reinforce the area to supplement the material that has been eliminated. This is usually done by framing the opening with reinforcements. In addition, it is convenient to reinforce the corners of the opening by placing, for example, twice the thickness of the laminate of the panel.
     
  9. rberrey
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    rberrey Senior Member

    To stop the crack from running farther you will need to drill a hole at the end of the crack . Even if I went for a structural fix with a glass lay up I would still drill and fill before patching .
     
  10. TANSL
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    TANSL Senior Member

  11. UpOnStands
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    UpOnStands Senior Member

    This is the actual boat or a sister ship? Cockpit from about 5:40. Appears to be no winches or clutches on the roof. The roof does extend some distance aft with no support pillars but not excessive overhang. Roof supported a mess of solar panels, clip on screens, people for mainsail flaking/stowing? none of the other corners (portside) have cracks?
    If the cracking is due to a design problem I would expect at least some of the other aft window frames to show similar cracking.
    No other cracking = design is good.
     
    Last edited: Mar 5, 2018
  12. Ad Hoc
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    Ad Hoc Naval Architect

    Based on the pictures, and the comment above of other boats of the same, it is clearly a manufacturing issue.

    Where there is evidence of poor fit up and saw cuts is at the worst location in terms of stress distribution around an opening, such as a window, and coincides with your cracks.

    Remove the whole radius regions and replace with one part that is specially shaped and smoothed, not made of several 'bitty' parts. So the wooden part has its joint either side and away from the radius. Thus one wooned part that takes up the whole radius with no joints. Time consuming , yes, but necessary.
     
  13. UpOnStands
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    UpOnStands Senior Member

    plus 1 on that.
    The below example is not good. Cost cutting or a rushed job?
    [​IMG]

    For rbeery. dry fit one half of the window/surround and determine how much clearance you have from the surround to the wood opening.
     
  14. mrybas
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    mrybas Junior Member

    That’s the actual boat from a video a previous owner took. There is nothing on the roof anymore (solar panels removed). I don’t think the window cracks are from roof loading however.
     

  15. mrybas
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    mrybas Junior Member

    What do you think about cutting out the wooden frame 3” from either side of the corners and replacing with a piece of G10 epoxy board?
     

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