Fiberglass Repair Option

Discussion in 'Fiberglass and Composite Boat Building' started by bucketlist, Sep 1, 2021.

  1. Mr Efficiency
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    Mr Efficiency Senior Member

    The backing doesn't take all the load, the feathered edge of the existing hull will take a lot, when the repair is finished. I am thinking the sheer thinness of it complicates the repair, in several ways, more flex, and the feathering having less surface area to work with.
     
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  2. fallguy
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    fallguy Senior Member

    Yeah. I updated my prior post to reflect that. Isn't there a limit on how big a hole one can fix with 12:1 feathering? Here 12x1/4" is only 3".
     
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  3. Mr Efficiency
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    Mr Efficiency Senior Member

    It makes it harder, with thin material. Certainly needs a firm backing that is part of the new structure, that the glass will bind to, but doesn't create a hard spot stress concentration.
     
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  4. bucketlist
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    bucketlist Junior Member

    Here are some pictures of location . 1.5 -2 '' port of keel center line (12 ''long ) and the second crack is 10-12 '' port of keel center line ( 12 '' long )
     

    Attached Files:

  5. ondarvr
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    ondarvr Senior Member

    Before doing any repairs the area of potentially thin laminate needs to be identified. If the area is large then it may eliminate the need for any repairs being done inside.

    You may need to add glass to a large area of the hull, since you can't do this from the inside easily, it can all be done from the outside.

    The edges of the added laminate can be hidden at the chine or strakes from side to side, and then possibly an extended taper where it can't easily be hidden.

    This isn't ideal, but it eliminates the need for cutting out the interior and solves the problem for less cost and hassle. Under bottom paint the repair wouldn't be noticeable and would have no effect on performance.
     
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  6. fallguy
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    fallguy Senior Member

    This is probably the best idea overall for the issues faced. You worry less about the bottom and take a hit on hull being perfect down there. Then repair the hole and then add some laminate to the outside that extends beyond the 3" taper grind.

    Another reason to find someone that will spec the work and have the repair guy work to specs. And also, if the break is 6" from the keel, then glassing to the keel beats a small taper.

    can you layout on graph paper the damage with references to keel and chine and stringers or any internals? You may find someone here to spec it for you that way. Not me.
     
  7. fallguy
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    fallguy Senior Member

    This area is really beat up and could be fixed really well by doing a hole repair(s) and then going over it with several layers of glass that go from bigger pieces to slightly smaller, etc.

    how fortunate you are to have @ondarvr reply

    BFD165F8-BCF3-4DB1-A8BE-4CB6724ED9C4.jpeg
     
    Last edited: Sep 2, 2021
  8. bucketlist
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    bucketlist Junior Member

    Unfortunately , the MFG won't share any info , no laminate schedule , no factory recommended repair procedure ( which they promised ) . They don't even offer to repair ABYC wiring infractions that can cause fire . The only specs ( from the Lab Tests ) i have is the 6.3 mm thickness , the 2 fiber thicknesses - 10-12 um and 20-22 um . polyester resin containing styrene , UTS strength 18.3 ksi , Yield 15 ksi , compression 29.2 ksi . ash content 55.8 % . This young man that would like the repair job , just started his own shop , has got 20 years experience ( 8 yrs in Canada at a fiberglass boat repair shop ) and working at his family business in Costa Rica building Pangas Boats . His references check out 100 % . I can't find anyone else in Ontario interested in repairing my boat . I am sharing all of the Boat Design Forum advice,with him , that all of you are sharing . I will be mentioning to him to join as there is a wealth of knowledge in the group .
     
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  9. ondarvr
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    ondarvr Senior Member

    Drill some 1/4" holes elsewhere on the hull and see how thick it is, anything similar to your sample may need more glass. And you may find out how thick it should be.
     
  10. fallguy
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    fallguy Senior Member

    I won't spec for you, but i would fix it with 1708,1808,1708 on the outside after conventional hole repairs using epoxy if it were my boat and I could not find anyone to spec it. There can be no gelcoat remaining to start and the substrate needs to be keyed with 40 grit. Because it is upside down, the best work would be done using vacuum after the holes are all fixed. And probably even using a hotcoat of thickened resin or even infusion. If he doesn't have vac; he can get a small pump for the work for like $200. The reason to use vac is to avoid air in the bottom. Air holes in the laminate on the bottom are subject to hydraulic erosion. Can it be done without? Yes. As well. No. Inspecting for laminate voids in handwork is critical.

    I'd follow ondarvr's exceptional advice and fix it chine to chine and about 6" past the damage for and aft each way. Since there are 3 pieces, something like 10",8",6" past the damage for and aft and then on the sides from chine to chine and minus two, minus 4 because going to the keel doesn't do much. You could also opt to go say a foot past the keel to starboard, but harder to finish as well. What you don't want to do is create hrdpoints and so the glass layers cannot directly overlap each other. Nor do small pieces go first. Biggest first. Many people falsely believe the 1708 and 1808 cannot be used with epoxy, but an absolute lie. The styrenes do not break down, but they do not need to. The mat will help stiffen things.

    Again. The best way is to pay someone to spec the repair. They may tell you the glass I suggested is excessive, for example.

    Also, I would not pull too much vac for the repair and use some holed release fabric. Noahs in Toronto can probably supply it all.

    you need to get the boat fixed so you can use or sell it and get past it
     
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  11. bucketlist
    Joined: Nov 2020
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    bucketlist Junior Member

    Thank you everyone for the advice . I am meeting the Fiberglass repair man tomorrow and will go over your advice with him . We will use the boroscope to check the inside areas to check on amount of edge for a good overlap etc. Thanks again
     
  12. rxcomposite
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    rxcomposite Senior Member

    I will wear my hat as a ship surveyor. If there is a local impact damage, the structure near the damage was also affected. This is evident from the picture provided.

    To further asses the damage, the interior/floor above the damage should be removed in order to accurately asses the damage so that appropriate repairs can be made. Check for any sign of delaminations.

    In the absence of original laminate schedule, a section must be cut out and burned (from another thread) so that the laminate schedule can be determined. The fiberglass will not burn but the resin will. This will enable you to separate the layers and identify the type of fabric used. The sequence is important and bear in mind that the keel is always thicker than the bottom laminate. Usually it is 1.5 x thicker than the bottom laminate. Most oftentimes, it is 2x. Do not assume that the laminate failed because it was weak from the start. I can see from the damage there is an impact greater than the allowable design pressure. Let us just assume the manufacturer did their homework.

    To start the repair, Prop the boat properly, make sure it is even and firmly supported. The damage caused the structure to skew, pushing some parts out of alignment. Cutting out the part will also allow the structure to "normalize" as the laminate has a memory. It will return to its original state/curvature. Properly propped, wait for a day for everything to settle.
     
    Last edited: Sep 2, 2021
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  13. rxcomposite
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    rxcomposite Senior Member

    Feather the edges of the cutout part. A 6:1 taper is acceptable in the boat industry but a 12: 1 is better if permissible or practical. Apply a temporary backing plate on the inside. Use Bondo to hold it in place. This will later be removed. Patch the hole progressively in accordance with the original laminate. It should be 50 mm larger for the original layer and progressively larger until the last layer is about 20-25 mm larger than the last layer. This will later be sanded and faired. When cured, remove the temporary backing plate and apply a fabric type glass on the inside for insurance. Thus you have original laminate restored + 1. Overlap should be 50mm. Do not overbuilt by applying too many layers as it will cause a stress risers and cracks will show later in the adjacent laminate. Epoxy is good but an overkill. The original resin type can be used.

    If you used polyester, laminating resin is used. It remains tacky after cure. The last layer inside should use resin with wax. Remove the wax with acetone if you need to paint it. If there is a need to gel coat after fairing, use gel coat with wax so that it cures without a tacky finish.

    Good luck in the repair.
     
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  14. fallguy
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    fallguy Senior Member

    @bucketlist

    Rxcomposite has proven himself to be a master of laminating.

    And I hope you don't get too lost in positive vibes from me and ondarvr. If the boat is broken away from stringers or bulkheads; it is a serious issue that cannot be overlooked and repaired outside only.
     
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  15. fallguy
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    fallguy Senior Member

    The problem present is the status of the laminate between the outboard damage 12" to port and 12" long and the near keel damage is unknown and probably compromised. So this means the hole is about 12"x12". I seem to recall OP mentioning a long area of delamination as well not discussed here. And his burn test did not provide the laminate schedule...nor did Rangertag.
     
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