Main bulkhead replacement

Discussion in 'Boat Design' started by N2everythg, Dec 4, 2018.

  1. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    No, I meant the boat is gone from the previous owner, they got their insurance payout (maybe, I'm trying to develop a theory as the OP is not forthcoming with info) and don't have to deal with boat because it's sold, to the OP.
     
  2. N2everythg
    Joined: Dec 2018
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    Location: nc

    N2everythg Junior Member

    not yet. in process. This is not a full time job. and I expect it will take me months. I've been busy with holidays, travel, kids, work life...

    Nor a "flip sale" blue bell. If I ever decide to resell I would disclose everything including repair photos and methods and price accordingly.

    To clear up what seems to be a bunch of confusion on how I obtained it. Yes the PO... previous owner .. pulled her in order to do a top side repaint several weeks before florence. They had been living aboard dockside and just found out they were expecting a baby in january. when the boat fell off the stands they had the boat yard evaluate repair damage cost and received an insurance check. I didn't get into specifics of how much.. but regardless. after evaluating the PO decided to sell rather than to attempt the repair himself or let the boat yard complete it. I assume the insurance wasnt enough and between that and the baby they decided to cut and run. I decided his price was right for what it was.. and in reality ya'll dont need to know what that is. its irrelevant to the point of this discussion. I though it was a darn good deal.

    what I was trying to obtain with this discussion here is additional methods of bulkhead repair when the bulk heads were installed prior to the deck being joined to the hull. And any other constructive suggestions for the strongest repair.

    I understand that I am asking this with out providing a lot of context, background information, etc. But the original post was really theoretical. What I was trying to ask was about methods to repair / replace a bulk head when the original wouldnt fit through a companion way hatch.. what is the strongest method? I have a few ideas of how I could proceed but was hoping for more.

    I am surprised that a site dedicated to boat construction engineering are not familiar with the Amel brand. But I guess if you dont focus on sailboats one might not know the name. Henry Amel is a very famous French designer and builder.
    Histoire – AMEL https://www.amel.fr/en/lhistoire/
    They are a very renowned blue water cruising sailboat that are built to very high standards and well known in the blue water cruising community.

    regardless....... current progress.. due to holidays and travel I have only been able to dedicate one long weekend to digging in deeper, winterizing the boat for a prolonged stay on the hard over the winter. removing running rigging that was still in place, a number of other boat tasks, etc.

    regarding the damage - Almost finished removing all the delaminated damaged glass from the hull breach to determine the extent of the breach and size of new repair patch and removed one stringer.
    I haven't finished grinding in the scarf for the repair but I have determined the extent of the delamination and how much of the hull will need to be cut out and how much scarf I plan to add. I do plan to move that scarf line back at least a foot from where it was marked in the photo.
    I can add a few pictures that might draw some attention to my original question ;).
    thanks,
    N2
     

    Attached Files:

    Last edited: Jan 28, 2019
  3. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    I am pretty sure the scarf ratios you cite are unneeded. I think what happens is the longer the scarf the more likely you will have a void or error. I wish I could give you the actual number but 1:12 is fairly typical. How would you ever scarf into the hull accurately at 1:100 without damaging good hull? Isn't that a 50" scarf for a 1/2" hull?

    A few of the pro builders here might advise, but I would use a much lower number and focus on using more glass to strengthen vs a unusual scarf.
     
  4. chowdan
    Joined: Jul 2008
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    Location: Seattle WA

    chowdan 1980 PAC41 Liveaboard

    Following this thread. I am a big fan of Amel. I would love to see how you do and what the end result will be of her.

    On a side note, talking about structural damage, you should check out the youtube channel Sailing Magic Carpet. I met the couple down in Baja MX last year before they set sail board SV Magic Carpet and talked with them pretty extensively over a few days about the repairs they did to her. Some of their early footage includes videos/photos of the damage their vessel took and what they did to rebuild her back into a beautiful vessel.
     
  5. N2everythg
    Joined: Dec 2018
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    Location: nc

    N2everythg Junior Member

    @chowdan.
    thanks.. I have seen the magic carpet vids on the reconstruction he did and have had several email conversations with him as well. seems like a great knowledgeable guy with lots of experience and know how.. gotta say his project was WAY bigger and more complex than this one. Magic carpet suffered a ton of damage from her fall.
     
  6. N2everythg
    Joined: Dec 2018
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    Location: nc

    N2everythg Junior Member

    a section of information found on the web when researching and trying to determine a new layup schedule for the glass. ...
    I knew the delaminated material I removed wasnt woven roving but hard to determine the exact weight of cloth that was originally used.

    "Construction
    All Amels, since 1967, have been built with Amel designed biaxial fiberglass cloth. This is a flat woven fiberglass cloth that is much stronger in sheer and tension than conventional mat and woven roving laminates. The hull is molded in one piece incorporating one piece/non-spliced lengths of biaxial cloth running from bulwark, down through the keel/centerline, and up to the opposite bulwark. In the same fashion the next series of laminates run from the bow lengthwise to the stern, again, employing one piece/non-spliced length of biaxial cloth. "

    "After all the structural assemblies are completely install, the separately completed deck assembly is joined to the hull, (again, while it is still in the mold) with six layers of the same biaxial cloth used in the primary lamination, around the entire hull to deck interface. What is accomplished, effectively, is the elimination of a conventional hull to deck joint. The hull and deck are married with a homogeneous fiberglass matrix, which insures a strong and lee free hull and deck join for the entire life of the vessel."
     
  7. N2everythg
    Joined: Dec 2018
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    Location: nc

    N2everythg Junior Member

    So I decided to use a peyson joint to repair the damaged bulkheads. Surprised that was not posted as a potention option.
     
  8. N2everythg
    Joined: Dec 2018
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    Location: nc

    N2everythg Junior Member

    Hull repair was completed with 13 layers of 17oz Biax and epoxy. Scarfed back a minimum of 48” fore and aft and a minimum of 28” above and below damaged area. 3 layers externally and 10 layers internal all overlapped 3-6 inches depending on location. Layers of Biax were alternated with glass strands at 90 deg and 45 deg alternating layers. Fill and fair and paint yet to complete. Currently working on bulkhead repair...
     
  9. N2everythg
    Joined: Dec 2018
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    Location: nc

    N2everythg Junior Member

    A few pics
     

    Attached Files:

  10. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member


    The hull repair looks awesome.

    There are times and places where a Payson joint is appropriate to use on boats. IMO structural bulkhead repair is not one of them. It is very difficult to engineer the FG scabs so that the joint maintains the same flex characteristics as the unaltered plywood. 10:1 scarfs do behave the same as unbroken plywood.

    Keep up the good work
     
  11. N2everythg
    Joined: Dec 2018
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    Location: nc

    N2everythg Junior Member

    Thanks for the input. And it makes sense. Perhaps I should have said “I think I’m going to use a peyson joint” as I’m really not committed yet or started that part of the repair. Appreciate your opinion

    BYW that exterior pic of the glass still has peel ply on it. It’s not milky or bubbles your seeing it’s the ply protecting it from UV and dirt til it cools off enough the fair and paint
     
  12. N2everythg
    Joined: Dec 2018
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    Location: nc

    N2everythg Junior Member

    So original main bulkhead is 5/8 marine ply. From what I can tell the original construction used a standard butt joint in the center no scarfing at all. I still need to study it closer as tat repair is still 3-4 steps down the road. Just trying to formulate a plan early.

    I was thinking that a 3mm deep peyson routered back 5-6 inches from the join on both sides of the bulkhead (I do have access) then layered with 3 layers of 1708 on each side would be stronger than the original ply. Worst case if I still didn’t trust it I could layer the entire main bulkhead wall (just the damaged 1/2) with 1 layer of 1708 after putting in the peyson. Then fair and paint the whole thing. In my mind that would be way stronger than the original.

    I would prefer to scarf but in the location that needs repair it would be almost impossible to create a precise scarf. It’s only damaged above the door and the tabbing is not even delaminated from the hull or cabin roof. Beats me how those forces worked to that effect.
     

  13. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    As is often the case, incomplete information can lead to in acute conclusions. I didn't know about original butt joint above opening. With that new bit of information, a Payson joint IS appropriate there.

    Forces can travel odd routes. I was once rear ended. The fire department had to bring a crowbar to open my glove box so I could retrieve registration and insurance documents.

    Beware. Peelply left long enough becomes extremely difficult to remove. I once had to grind some off.
     
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