Crack Back

Discussion in 'Boat Yard Basics' started by goodhands_gheenoer, Jun 25, 2009.

  1. goodhands_gheenoer

    goodhands_gheenoer Well-Known Member

    159
    0
    341
    I bought a used 97 Classic a short while ago and it had a small crack where the back flotation chamber meets the transom on the inside. The transom seems solid with no soft spots and it was stored in a garage. I took pics earlier and will transfer them to the site tonight. Need your thoughts on repair. Is it a matter of 5200 in the crack to seal out water, or does it require fiberglass work?
     
  2. Un-shore

    Un-shore Well-Known Member

    I think 52 would be a good quick fix. You can still grind the area over and epoxy it later.
     

  3. goodhands_gheenoer

    goodhands_gheenoer Well-Known Member

    159
    0
    341
    Hope this picture posts. If someone can fix it I appreciate it.

    IMG]http://i688.photobucket.com/albums/vv242/redgheenoe/Transomcrack002.jpg[/IMG]
     
  4. Brett

    Brett > PRO STAFF <

    You almost had it...just left a bracket off the front...  [ 

    [​IMG]

    That looks to be a little bit deeper than a stress fracture.  :-?
    I'd grind it out and reglass the area.
     
  5. goodhands_gheenoer

    goodhands_gheenoer Well-Known Member

    159
    0
    341
    OK--So grind it back and reglass. This is new to me. Once I grind (1/2 inch around the crack?) to expose area for adhesion, do I fill void with something before laying glass mat over the crack?
     
  6. paint it black

    paint it black Paddling away...

    6,208
    845
    2,328

    You might want to drill out the ends to ensure that the crack will not continue to grow once glassed over.
     
  7. Brett

    Brett > PRO STAFF <

    Take a couple more pics of that area from top left and top right
    looking back at the transom and post them. I'd like to see how
    far the crack extends along the float chamber.
    And one from the outside so I can check the exterior gelcoat.

    To repair the crack you'll have to remove the interior gelcoat at least
    4 to 6 inches each side of the crack to create a strong bond to
    the existing structures. Don't use just mat, add some woven
    fiberglass layers to the repair. Fiberglass mat doesn't make for
    a strong repair. Alternating woven with mat produces a stronger
    more durable patch. Not a hard job, just messy.
     
  8. goodhands_gheenoer

    goodhands_gheenoer Well-Known Member

    159
    0
    341
    Thanks Brett--I will take some more tonight--here is one more I took earlier.

    [​IMG]
     
  9. topnative2

    topnative2 Well-Known Member

    2,201
    377
    938
    brett is rt. ---but use bi-axial cloth and epoxy---start w/ small patches going progressively larger---as suggested
     
  10. Un-shore

    Un-shore Well-Known Member

    That is bigger than I thought. you will want to cover your hands and arms before grinding or you will be itchy.

    Hey guys, I've heard that mat has a wax on it to bind it together and epoxy does not have the chemical reaction to remove this wax and will not bind well. Can anybody verify this or is there two types of mat?

    Also GG, do you know if there might be water inside the chamber and might have waterlogged the foam?
     
  11. Brett

    Brett > PRO STAFF <

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    Those cracks are known as hard point fractures.
    Fiberglass is very flexible except at sharp bends.
    Any time a flexible fiberglass panel meets a hard point (sharp bend),
    the possibility of a fracture occurring goes up greatly.
    The transom is laid up as a single fiberglass skin
    with the rest of the hull. The floatation compartments
    and benches are added afterwards and are not built as well
    as the rest of the hull. So any hull flex transfers unevenly to
    the components glassed in later. Your fractures appear to
    be caused by the weight of the outboard shaking the transom
    which has caused the separation fractures you are seeing.
    The transom is peeling away from the benches.
    I can tell this as there are no cracks on the outside of the transom,
    and the symmetric fractures to the tops of both benches.
    Is the bottom of the transom and hull properly
    supported by the bunks on your trailer? If not, after making
    the repair, those fractures will occur again.
     
  12. goodhands_gheenoer

    goodhands_gheenoer Well-Known Member

    159
    0
    341
    I don't think there is water in it as it has been covered. Not sure how I would know unless I made the hole bigger. :eek:
     
  13. tom_in_orl

    tom_in_orl Founder of Microskiff, Member of the Gheenoe Army

    Do you work for Gheenoe or just stay at a Holiday Inn Express? JK, ;) but I think you might be reaching a little there unless you have inside knowledge.



    Is that a Classic hull with a rear bench seat? If so the area under the crack is open to the bilge and contains closed cell foam. Because of the open nature it can be damp in there but it should not affect the fiber glass when you go to repair it. Grinding off the gel coat to do the repair will confirm it.
     
  14. goodhands_gheenoer

    goodhands_gheenoer Well-Known Member

    159
    0
    341
    It is a Classic with rear bench seat. I'll check it out.
     
  15. tom_in_orl

    tom_in_orl Founder of Microskiff, Member of the Gheenoe Army

    Poke your head under the seat and look over towards either side. You will see what I am talking about. You will find it makes it easy for running plumbing or wiring like this picture where I have the electrical running out one side and fuel on the other.

    [​IMG]
     
  16. kuzus

    kuzus www.fgci.com 800-272-7890

    20
    0
    331
    Hey guys, I've heard that mat has a wax on it to bind it together and epoxy does not have the chemical reaction to remove this wax and will not bind well. Can anybody verify this or is there two types of mat?


    Chopped Strand Mat is held together by a chemical binder that is broken down by styrene allowing it to "wet out". Epoxy does not contain styrene, so it is unable to break down the binder holding the mat together.

    but use bi-axial cloth and epoxy

    I would not use epoxy for this job. If you use polyester resin, you can easily use gelcoat to finish off the repair and match it to the rest of the boat. Polyester is also cheaper and you won't have to worry about future issues with bonding a polyester to an epoxy.
     
  17. goodhands_gheenoer

    goodhands_gheenoer Well-Known Member

    159
    0
    341
    After getting a very generous offer by Pugar to fix the problem, scheduling issues and distance to the shop will not make it easy so I've decided to fix this myself. I have started sanding the area and getting it ready to glass. I do have a question. Now that I've sanded the area, how many layers of glass mat is needed to be laid down? If more than one, do I put them on together or glass--dry--sand--then lay another layer?
     
  18. Un-shore

    Un-shore Well-Known Member

    you just need enough glass to make it level with the existing surface . that would be one of those guesstemant deals. the most important part would be to grind the area wide enough to spread out the bond area and feather the grinded area so you get some depth into the existing fibers.

    I would do it all at once so you dont have to grind the new glass for the next layer.

    also, you don't want more resin than fibers or vice-versa. not to dry or too wet.
     
  19. Brett

    Brett > PRO STAFF <

    mat mat mat mat matmat mat mat mat mat mat mat mat mat mat mat mat mat mat mat
                          biax biax biax biax biax biax biax biax biax biax biax biax
               matmat mat mat mat mat mat mat mat mat mat mat mat mat mat mat
                             biax biax biax biax biax biax biax biax biax biax biax
                    mat mat mat mat mat mat mat mat mat mat mat mat mat mat
                                                             crack


    layup make sense?

    Cut fiberglass to fit
    mix polyester resin with mekp per instructions on container
    apply resin with 2 inch cheap bristle brush

    apply resin, set mat, apply resin, set biax,
    apply resin, set mat, apply resin, set biax,
    apply resin, set mat, work out all air bubbles,
    let harden, sand irregularities smooth.

    Throw 2 inch brush away... ;)
     
  20. kuzus

    kuzus www.fgci.com 800-272-7890

    20
    0
    331
    You could probably get a better resin/glass ratio if you only do one or two layers at a time. If you lay up subsequent layers while the previous one is still tacky you can avoid have to sand in between. Also, if you use a knitted biaxial material like XM1708, or a stitchmat (woven roving with mat stitched on) you could avoid having to lay mat between layers. They will also build thickness in less layers. The downside to those products is that they have a larger profile and might require more fairing than a biaxial cloth like Brett is talking about. If it were me, I would go with the XM1708, but Brett's method is a good option as well. Keep in mind that regardless of the glass you use, you want to use the least amount of resin possible without leaving any dry spots in the glass.

    If the crack is only in the gelcoat, this in no big deal. If the crack goes through into the glass, then you have a structural issue. If the latter is the case make sure you wrap the glass up onto the transom to reinforce the area.