Sealing bolt holes in transom

Discussion in 'Boat Tips' started by cjb10876, Mar 4, 2007.

  1. cjb10876

    cjb10876 New Member

    Messages:
    59
    State:
    Pennsylvania
    I will need to replace the transom in my little 14' aluminum boat before I take it out this season. I was going to use plywood and stainless hardware, but my question is what I need to use to seal the bolt holes. Do I use plain silicone sealant (tube type) or are small rubber gaskets better? Or am I totaly off and need something different? this doesn't look like to hard a job, I just want to do it right so it will last at least a few seasons and first and foremost be safe.
     
  2. AwShucks

    AwShucks New Member

    Messages:
    4,532
    State:
    Guthrie, Oklaho
    Mark had a post on here a few days ago which made an incredible amount of sense. He stated to fill a bolt hole so the water could not get to the transom, to drill the bolt hole a larger diameter than needed. Fill the hole with a good grade of marine sealant (and there is a difference in sealant). After it cures, drill the middle of the hole out for your bolts securing the transom to the boat skin. This is the only way to protect the wood from water as it will leak through the screw threads. Now that I have replaced my transom the first time (aluminum boat of course) it's no big deal if I have to replace it every two or three years. But Marks post made a lot of sense. If your like me, when bolting your transom back in place and before you tighten the bolt, you apply a coat of the marine sealant. Then fasten the bolt and place more sealant over the bolt head. The logic being if you seal completely around the bolt water won't get to the transom. Maybe one of the brothers can provide a link to that thread.
     

  3. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    That method is using thickend epoxy on wood penetrations.
    you drill the hole larger then needed, fill it with thickend epoxy then redrill to the proper size. this totally encapsulates the wood in the hole.

    Stainless steel fasteners. Stainless doesnt rust because of oxygen. Take the oxygen away and it will rust.
    Meaning if you seal a stainless bolt on both sides of the transom and water gets in the transom, it will rust like a steel bolt.
    Stainless is also weak unless you buy the high grades. Because its hard to cut doesnt mean its shear strength is strong.
    I've stripped out 1/2" stainless bolts and instead of cutting them took two wrenches with a quick jerk and snapped them.

    I like stainless but you also have to be aware that stainless isnt bullet proof.
    Spring for high grade. There is a Fastenal store most anywhere in the country. They have an awesome stock of bolts, taps, and washers of all kinds. They also carry alot of different adhesives and TOOLS:0a26:
    I love Fastenal. They are more then just fasteners. They are almost identical to a McMaster Carr or any other large industrial supplier.

    If you ever use stainless fasteners and when tightening you hear a squeak. You have gauded the threads ruining the fastener. They make a thread compound for stainless that is blue in color that will greatly reduce this from happening.
     
  4. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    There's also a teflon thread coating that comes in a syringe that only requires a small spot on the stainless threads that helps prevent that squeeking noise.
     
  5. KansasKatter

    KansasKatter New Member

    Messages:
    807
    State:
    Wichita Kansas
    One more thing I would add to Mark's method of sealing the holes in the wood, if you countersink the oversized whole on each side, before the epoxy, it will be much stronger, as it will sort of form a "wedge" from each side. Does not have to be much, just a little. Gives the epoxy just a little more to grab.
     
  6. navigator

    navigator New Member

    Messages:
    199
    State:
    NC- Brunswick County
    not sure but I was told you shouldn't use stainless bolts in aluminum because the stainless would cause electrolosis in the aluminum.

    I don't rememeber where I heard that from, anyone know if there is any truth to it?
     
  7. BILLYP

    BILLYP New Member

    Messages:
    415
    State:
    Fayetteville, North Carol
    Just to add to the others, use expoy for your filler, it holds tight and is very enexpensive. I just bough a tube from walmart for around 6 dollars, and they come in stick form so you don't have to mix it yourself.
     
  8. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    That isnt marine epoxy.
    For a job this small I would spend the 15 bucks for the epoxy trial kit.
    it will have enough of what you need.
     
  9. BILLYP

    BILLYP New Member

    Messages:
    415
    State:
    Fayetteville, North Carol
    It says that it is marine grade epoxy on the tube, and it has a picture of a boat on it. If this isn't marine grade what would be? I have tried the kit and it dosen't work as well as this stuff from what i have encountered. But thats just my opinion i guess.