Repairing transom delaminate

Discussion in 'Fiberglass and Composite Boat Building' started by nikous, Nov 30, 2010.

  1. nikous
    Joined: Nov 2008
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    nikous Junior Member

    [​IMG]

    [​IMG]

    I would like your help to repair a part of transom delaminate. Firstly, as you can see at the picture, the big hole is created by the manufacturers. They cut the plywood so that putting an aerator pump! Wrong and unbelievable! I recently discovered this, when I decided to remove the pump. The boat is 5 years old.
    There is a gap of the interior skin between plywood and glass, but this is not the problem because the gap is small. Delaminate is bigger outside (you can not see this at the picture) up the engines bolts. (The cutting hole is on the left end of the transom).Also, the wood is damp but not rotted, due to water. (There is water-tight space including the pump which is covering with marine sealant).
    As for outside delaminate repairing I’m thinking drilling 1-2 small holes on the glass of the transom, where the higher delam point. After, I’ll fill polyester resin in the gap with a syringe. Is this the right job?
    I don’t know how I can dry the damped plywood without remove the whole fibreglass.
    I’m thinking the rest job is not so difficult.
    Any idea would be welcome.

    Thanks
     
  2. gonzo
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    gonzo Senior Member

    If the wood is wet, resin will not stick to it. The only proper repair is to cut out the wood and replace. Are you sure there is no deterioration around the engine bolts?
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Your repair approach will not fix much with a delaminated, dirty and wet core. You may not see rot, but I'll bet you have plenty, probably at the bottom of the transom core and working it's way up, you see gravity always pulls the moisture down and the rot starts at the bottom and grows upward.

    The only real effective solution is to open up the transom, dry or replace the core, grind all surfaces clean, then bond in a new core or repair the current one. Polyester wouldn't be the best choice for this job, epoxy would be, because it's sticks to wood much better, is waterproof unlike polyester and will bond with much higher strength.
     
  4. War Whoop
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    War Whoop Senior Member

    You will need to drill a few holes to find the extent of the water intrusion.
     
  5. nikous
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    nikous Junior Member

    Surely as you describe is the proper way.
    If I repair it as I described closing the moisture inside, how dangerous could be? The transom has no cracks. The hole is only 1 inch from the bottom of the transom.
    Thanks for the replies

    Here is a pic where the pump in a new boat
     

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  6. gonzo
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    gonzo Senior Member

    Trapping water in will cause the wood to deteriorate very fast. It is the ideal condition for fungus and bacteria to grow. If there is enough oxigen, fungus (for example mildew) will create dry rot. If there is no oxygen, anaerobic bacteria will eat the sugars in the wood, and ferment it into alcohol.
     
  7. stilloutoffocus
    Joined: Apr 2009
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    stilloutoffocus dealership repair flunkie

    im not as fancy pants technical as these brains here but in my experience any wet wood in a boat only leads to bad things. unfortunately i see a lot of improperly sealed thru-hull fittings and screw holes in my line of work and you have a lot of transoms being replaced within 15-20 years of manufacture. most of these by the time i get them i call "rake-out" transoms because you can just drag your fingers across the "wood" to dig out the rotten core material. if you plan on keeping this boat around my best advice would be to just bite the bullet and get out any wet wood now while your problem is small rather than spending a couple thousand dollars on a transom replacement in a few years.
     
  8. nikous
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    nikous Junior Member

    Many thanks all. I maybe will need your helps again.
     
  9. LMB
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    LMB Junior Member

    Have you checked your warranty? Also, you might be able to achieve a repair by injecting as you described - only use West System G-flex or Git-Rot formula for damp applications. These are the only resins I know of that will work in damp (not wet) applications but there may be others. West System has a good user manual that shows how to inject properly for delamination repair. You could also add a good size backing plate to add some integrity. Keep in mind this is not an ideal repair and not how I typically do things but it may work. Consider the overall structural integrity of the transom and keep it checked for signs of failure. Hope this helps.
     
  10. nikous
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    nikous Junior Member

    The boat is 5 years old. The warranty was for 3 years. I knock my head now. When I bought the new boat I wanted to remove the pump from the day one but the local dealer said no.
    Sure the transom is very strong yet. I don’t know what will happen.

    How the Git-rot works? Is a resin used with fiberglass?
     
  11. Stumble
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    Stumble Senior Member

    Nik,

    Get-Rot is a pretty terrible product. What it is, is a very thin two part epoxy with minimal strength that is sold at about 5 times the price of regular epoxy. They say that the thinner formula helps it penetrate rotten wood, and reinforce the wood fibers. The reality is that the penetration thickness of Get-Rot is about 5% greater than a traditional epoxy at an inflated price, and with about 1/10 the strength. Secondly it cannot penetrate wet wood since the water is already taking the space where the epoxy would go.

    The only reasonable repair in this case it to drill a series of small (1/8 inch) holes radiating around where the pump hole is, looking for rotten and wet wood. Once the extent of the damage is known, you have to remove the damaged wood (either by removing one side of the transom, or drilling access holes into the skin), replace it, and then patch the transom.

    The problem with encapsulating the currently wet wood is that the water will remain, and continue to act as a vector to rot out the remaining good wood. If this happens it will turn a likely expensive repair into a boat that is sent to the scrap yard, hopefully without sinking.


    There is also a posibility that the amount of rot is localized to just around the drain hole. If this is the case it may be possible to remove the rotten wood by scraping it out through the hole, letting the damp but not rotten wood dry out, then replacing the damaged core with a lightweight thickened epoxy. I would only recomend this is the radius of the rot is less than about 2 inches, and I was sure I could access all of the rotten core.
     
  12. PAR
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    PAR Yacht Designer/Builder

    Stumble beat me to it about GetRot. It's not worth the containers they sell it in.

    You could try to remove the core around the area with an "L" shaped tool. I've made these on several occasions, to hack out wood inside a transom or other cored area. Some flat bar stock in a 90 degree angle, chucked up in a drill with the "leg" potion of the "L" tool sharpened on a bench grinder. It'll hack up the core and you can vacuum out the chunks. Make the leg of the "L" longer until you run into dry core material.

    Once you've gotten into good core, back fill the hole with thickened epoxy, let cure then drill the epoxy for new through hull.
     
  13. LMB
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    LMB Junior Member

    Please note, I only mentioned the Git Rot brand because they have marketed a formula for damp repairs (not the regular formula). I know nothing of the products cost or performance, just that it may be an option. West System epoxy which I also mentioned are great products with excellent customer service but if you attempt a repair in damp areas please realize you will need an epoxy designed for damp repairs like g-flex (most epoxies are not). I agree that removing any wet wood is the only true solution, but depending on access I realize that this can be a difficult proposition. In most situations I would rather just replace the whole transom than attempt to remove bits and pieces and fit in a new repair. If the area is small and accessible then o.k. I agree that the first step would be to drill holes to find the full extent of the damage. This will also aid in drying the core.
     
  14. nikous
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    nikous Junior Member

    Glad I come in on this very helpful forum. You gave me the best ideas.
    PAR, the plywood is not rotten (at least as I can see through the hole), only wet, so is very hard job to remove it from the small hole. In addition I have difficult access from inside, without cutting the boat.
    I’m thinking now drilling small holes so that found the extent wet plywood, as Stumble and LMB say.

    Hypothetical, if I found the wet (under waterline) plywood, that’s means that piece of the transom must cut out.
    My question: Can I do this job from the exterior only side replacing with a new piece of wood? That piece won’t be so “big”? Is this a properly building, patching with fiberglass only the replacement plywood? Finally, how long could be the new wood, so that giving a feeling of safe?
    This is an easier job for me. I would be happy if you say ok.
     

  15. Stumble
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    Stumble Senior Member

    LMB,

    There is no epoxy in the world that can reasonably be applied to wet wood in an encapsulated area. There are some epoxy's that can be applied underwater, or to bond wet parts, but as soon as epoxy encapsulates wet wood the wood is as good as rotten, and the only option is to remove it.





    N,

    If the wood is not rotten, but only damp you have to determin the amount of water penetration. Since sometimes wood will rot first downhill from where the leak is, particularly if the leak can dry while the interior wood cannot. To determin this you need to drill four small holes about one inch from the outside of the drain hole. Drill in a diamond pattern with one of the holes being directly below the hole. If anyone of these test holes shows wet wood then you need to continue the exploritory drilling until it comes out dry. I always mark each hole with a crayon W or D so I don't forget which is which.

    So long as all you find is damp wood, but no rot you can let the transom dry out. Dehumidifiers and fans can speed this process up, but it will still take some time. Only after you are SURE the core is dry can you then fill the holes, and repair the pump hole that started this problem.


    If you find rot, IT MUST BE REMOVED. No ifs ands or buts. Failing to do this now will result in a long slow (hopefully) continuing rot problem through the core that will spread. Once this gets to big the boat is usually not worth saving, and is instead scrapped.

    If the decision is to cut open the transom to replace the wood, it really doesn't matter which side of the hull is removed. If you have better access to the outside of the hull then start from there. Identify how large a section you will need to remove, then if possible using a hole saw you can cut out a plug slightly larger than the expected repair. This way you get to keep the hole as a plug when completing the project.

    As for the type of wood, most transoms are made of 2 layers of 3/4" plywood glued together then encapsulated in fiberglass. This is a little tricky to duplicate because of the repair, so my advice is to first use epoxy to bond the pieces together (matching the thickness of the existing transome), then coat the patch in two coats of unthickened epoxy (west systems is fine) to waterproof it.
     
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