Fiberglass and repair question

Discussion in 'Boatbuilding' started by MooseTrack, Jul 4, 2014.

  1. MooseTrack
    Joined: Jul 2014
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    MooseTrack Junior Member

    Hello Everyone and thanks for your assistance in advance. I recently purchased a 16 ft ceder strip sailboat that needs some hull repair. The fiberglass was cracked almost the entire length of the hull which included the area around the centerboard trunk. I removed the bad fiberglass and sanded the area. The repaired area is about a foot wide and approx 16 feet long. I have a few questions since I have never refinished a boat before. I have experience in fiber-glassing and auto body work. So, what would you suggest would be the best product to repair this boat and what is the best way to fiberglass the inside of the CB trunk. Thanks. Jim
     
  2. philSweet
    Joined: May 2008
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    Welcome to the forum. Can you upload some photos? To do that, open the reply window click on the "go advanced" button. At the bottom of the new window, you can find the attachment manager.
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    If it's a cedar strip build, your skills with automotive resins will not be very helpful. The techniques are similar, but the resin system is epoxy on your boat, which is quite different then the polyester used in automotive applications.

    It sounds like a simply repair, but photos and your goals will be necessary. If it's brightly finished hull the work is more tedious, but if it's painted, anything can be hidden under primer and paint.

    Lastly, it's probably a good idea to find out why it has a 16' long breach in it's sheathing, so it doesn't reappear after you've made the repair.
     
  4. MooseTrack
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    MooseTrack Junior Member

    Thanks for the info...I will attempt to upload some pictures
     
  5. MooseTrack
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    MooseTrack Junior Member

    Here are 2 pictures of the hull after the damaged fiberglass was removed
     

    Attached Files:

  6. MooseTrack
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    MooseTrack Junior Member

    So, any advice, suggestions on the best way to fiberglass the CB trunk and the best material to repair this boat? Also, in your opinion how much overlap from the repaired are to the good glass. Any advice or suggestions greatly appreciated...thanks
     
  7. CloudDiver
    Joined: Jun 2014
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    CloudDiver Senior Member

    Moose, there is a lot to take into consideration here.
    - You said the 'repaired area', that is just the area you sanded away the cracked glass right? Do you think it might have been repaired once before? The lighter colored wood of the Keel is obviously not cedar strip, likely white oak or possibly ash. The dark stains in pic #1 are from moisture intrusion.
    - In Pic #2 it looks like they used flat head wood screws on the ends and galvanized nails in the middle, several having staining around them from moisture intrusion.
    - So I have to wonder what the condition of the centerboard case is on the inside. To answer your question there really isn't a way I know of glass the inside of the original CB Truck when it is that narrow. The inside surfaces are typically glassed when the box is first assembled and a long dowel can be used to smooth fillets in the corners.
    -Hard to determine from the pics on what all has to be replaced vs. just re-glassed. It begs the question on how the damage occurred in the first place. Without seeing the overall construction of the boat (inside as well) I can only make my best guess is that there is not enough structural support around the CB trunk, causing the hull to flex and stress cracking the glass.
    - Conservatively I would venture to say the CB Trunk needs to be re-built from new material and installed with additional bracing. The keel may need to be replaced as well, although it might not be as bad as it looks.
    - Being a lake boat had it been hauled up on the beach? A rocky beach? If it had been dragged enough that may have caused enough abrasion to warrant using a strip of Kevlar but that could be over-kill.

    If you could post a few more pictures of the inside of the hull as well, especially the CB trunk and tell us if you can see water damage that may be more helpful.
     
    Last edited: Jul 7, 2014
  8. MooseTrack
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    MooseTrack Junior Member

    Will do. The CB Trunk it's self is in good shape. The sailboat was stored in a garage since 2002 and was for sale at an estate sail. When I purchased it I looked underneath it and did no see the damage because it was on a trailer. When I trailer-ed it home an a very bumpy road I believe the crack got worse. In my opinion, at some time moisture got between the the 'glass' and the wood around the CB trunk and caused the damage. The CB trunk and keel are in fine shape and the rest of the wood in the area is solid. I will take some more pictures and maybe that will help.....thanks a bunch for your help.
     
  9. CloudDiver
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    CloudDiver Senior Member

    The additional pics will help. This might not be a very difficult or time consuming repair at all.
     
  10. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The centerboard case is a well known area for issues. The usual fix is to remove the case, bust it open, make repairs, usually involving a new king post or two, then reattach it to the hull.

    A true strip plank 16' sailor, wouldn't need through fasteners in the case logs, just a heavy fabric schedule over a generous fillet. You could install them, but they're just a path to the inside of the planking and hull. On a boat of this size, 3 layers of 12 ounce (400 GSM) fabric, in a healthy structural fillet will do, assuming the top of the case is also well supported.

    As to the crack, I doubt a bumpy ride on a trailer would have cracked the sheathing. Maybe some localized stress cracks in the goo, near each roller, but not a full length "unzippering" of a seam like that. It's probably the oak (my assumption) center plank has let go of it's neighboring strips, possibly because the tannins weren't removed before assembly or because they used a PVA for the strips, instead of epoxy.

    Identify the adhesive used on the strips. PVA's will be brown, while epoxy will be creamy off white (when sanded). If it's PVA (TiteBond III usually) joint creep is the likely suspect. Since not much will stick to cured PVA, you'll need to remove the center plank (a real *****), mill off the edges to remove the PVA and dress the neighboring strips, before epoxying back into place.

    Also more photos to off the hull, inside an out.
     
  11. SukiSolo
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    SukiSolo Senior Member

    It looks as if those screws maybe plated steel, not Stainless Steel. An awful lot of black marking visible n the timber. If as PAR says, it may be oak, then mixing with steel will lead to blackening. In which case they have to come out and at minimum get replaced.

    Personally, I do not understand this build - yet. If I was building something on these lines, I would have laminated the bedlogs for the case or screwed and glued them but underneath the final stripping.

    Pray it is not Titebond or soggy Cascamite as there is no real alternative to taking the joint apart, cleaning up and reglueing with better adhesives. At least if the joint has failed and it is a dry brittle adhesive, clean up is straightforward. PVA tends to be whiteish (this side of the Pond) and be rubbery as well as a pig to get out of the grain, even planing a bit off. Had a joint go on an old Mirror gaff, and someone had put PVA into the 'split' to hold it. I just eased a chisel along the joint, split it and prepared each face with the plane and reglued. Worst bit by far was the PVA embedded in some parts of the grain. The reglued joint has already done a couple of months service, no problem.

    In the worst case, removing the case and replacing the hog which seems to be keel too, at least the strip construction will hold the shape, unlike some other forms of build.
     
  12. PAR
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    PAR Yacht Designer/Builder

    Yeah, it's a tough one without more images of what's going on, but centerboard cases are quite notorious if not well made. I often use a belt and suspenders approach and toss some fasteners into the case logs and king posts (centerboard case end pieces), plus a hefty fillet and fabric schedule.

    It's pretty rare to "get lucky" with these, as you don't know about problems until they're leaking, which only comes after considerable deterioration of the joints. This means you have to bust them open, which often requires near destruction, so you make a new case, hopefully saving the board.

    The lighter colored PVA's tend to be the non-waterproof "carpenter's glues, on this side of the puddle. Some of them are water resistant, but a centerboard case needs a truly waterproof adhesive, like epoxy, though polyurethane and others could be made to work too.

    Also agreed about the trouble PVA's can pose, after it's been in a joint and soaked into the grain. Sometimes you have to remove a fair bit of material, to insure another type of adhesive can bond to it. The limited testing I've seen on this suggests, the the new foaming PU's can bond to PVA's, certainly much better then epoxy. The only draw back is, the joints need to be well fitted and a lot of clamping pressure during the cure, unlike what's needed with epoxy.
     

  13. MooseTrack
    Joined: Jul 2014
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    MooseTrack Junior Member

    Thanks for all of the input....I will add new pictures ASAP for you to interpret. Where is a good place to purchase the amount of cloth needed?
     
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