Transom Repair Question

Discussion in 'Fiberglass and Composite Boat Building' started by Andrew Courtney, Jul 17, 2019.

  1. Andrew Courtney
    Joined: Jul 2019
    Posts: 2
    Likes: 0, Points: 1
    Location: Williston, Fl

    Andrew Courtney New Member

    Hey everyone. First post and new member.

    I had a recent run in with a rock and it caused the transom to crack the bond at the cap. It is right at the point where the jack plate, motor and power poles are mounted. I am working with a couple different boat builder/repair companies to get it fixed. One of the more reputable companies in our area told me they would cut out a three foot section of the composite transom, replace and reglass. The thing I am having a hard time getting my head around is, if they cut a section out of the core and replace it, how would they be able to keep the integrity of the transom? I don’t understand how they would tie the core together with a new section and still have the strength needed to support the motor and accessories. Their response was putty and glass would bond it. Can someone please help me understand or am I right in the idea that it would weaken that area. Thanks for any input.

    Andrew
     

    Attached Files:

  2. gonzo
    Joined: Aug 2002
    Posts: 13,558
    Likes: 374, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    From the brown discoloration at the edge, it looks like it may have had water intrusion for a long time. It is common to remove the inside skin, bond a new core and laminate new fiberglass.
     
  3. Ad Hoc
    Joined: Oct 2008
    Posts: 6,107
    Likes: 355, Points: 83, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    Hi Andrew, welcome to the forum.

    If you remove a section of the transom, there are 2 conditions to satisfy.
    1) The core.
    So long as the bonding material that butts and joins the old core to the new core, has the same or greater shear strength than the core, it is fine. Since any shear loads can pass from the old to new and vice versa via the adhesive that bonds the 2 cores together.
    2) The skins.
    So long as the laminate that is used is the same or greater strength than the original and there is no reduction in stiffness/strength, again you'll be ok. The important part will be bonding of the old and new laminate, just as with the core.
    This is often achieved by over laminating the joint.
     

  4. Andrew Courtney
    Joined: Jul 2019
    Posts: 2
    Likes: 0, Points: 1
    Location: Williston, Fl

    Andrew Courtney New Member

    Thank you both. I have been told by all the people who did my estimates that they believe the core to be composite and still solid. I think some of the browning is from corrosion on the old bracket that was over this area as well as the hardware there.

    So cutting the middle section out only and replacing that with the correct bonding material (I’m assuming that would be the putty they are referring too) and getting a good bond to the old glass and the new core and finishing with new glass will be sufficient if done correctly. That does make me feel better about that. Hopefully they won’t find any surprises when they get in there.

    Thank you again for the quick responses.

    Andrew
     
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