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Disappointing survey today...

Discussion in 'Technical Discussion' started by Norseman, Oct 23, 2015.

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  1. Capt J

    Capt J Senior Member

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    I don't remember exactly but seem to recall airex had issues with it gassing off as it aged and delamination, but do not quote me on this as it's been over a decade since I've heard anyone mention Airex.
  2. olderboater

    olderboater Senior Member

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    All cores can be done very well or very poorly, whether Airex or Balsa or any other material, but then boats that aren't cored can have issues. It's really just a matter of quality of build, followed by quality of maintenance and care.
  3. Norseman

    Norseman Senior Member

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  4. Capt J

    Capt J Senior Member

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    I wouldn't want a boat that is cored below the waterline, ever. Hullsides yes, below waterline no.
    My only exception would be a cold molded SF.
  5. Norseman

    Norseman Senior Member

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    Yeah, that has crossed my mind as well, no core below the waterline.
    If I find a good one however, no abuse or no damage, then I could use and maintain it for a long time with no issues hopefully, as I would make a priority not drilling holes or running into rocks:)
  6. Pascal

    Pascal Senior Member

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    I think the possible issues between balsa and foam core are too differed to lump them together

    The problem with balsa is that once you get water in, no matter how little, the core will rot and the damage will expand. This is why maintenance is so critical. On the plus side balsa will absorb resin creating a strong bond to the glass

    Foam cores on the other hand will not rot and being closed cell will not absorb water but it will not bond to the glass as well as balsa.

    Remember that boats are pretty much all hand built and that it doesn't take much for an area to be resin starved resulting in poor lamination. Especially as builders try to save weight and resin costs...
  7. K1W1

    K1W1 Senior Member

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    And cheap in experienced labour/labor is used to lay them up.
  8. Norseman

    Norseman Senior Member

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    Copied from a review by Naval Architect and Surveor Jack Hornor:

    She is solidly constructed utilizing conservative, time proven construction techniques and quality materials. Core materials are used in the construction of both the hull and deck structures although care is taken to use non-absorbent materials at through-hull fittings and attachments. Vinylester resin is used in outer laminates and osmotic blistering has not been a problem.

    Structural strength is provided by two fiberglass-encapsulated longitudinal stringers and plywood bulkheads all securely and neatly attached with fiberglass tabbing. The hull and deck are joined in a shoebox fashion with adhesive sealant as well as nuts, bolts and washers. The quality of construction, fit and finish is at the level of upscale productions builders.
  9. Pascal

    Pascal Senior Member

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    Builders have been using plywood bulkheads for years and owners have been fixing bulkhead rot for just as long.

    Why not use foam core? Is it because divinicel cost 4 or 5 times what plywood cost?
  10. Norseman

    Norseman Senior Member

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    No idea, not a boat builder like you:)
  11. Norseman

    Norseman Senior Member

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    Not being snarky Mr. Pascal, I know you built your own boat and hat off to you Sir.
    My expertise, if any is (was) to maintain a CSY 33 sailboat so as to keep in Bristol Condition, then sail her to the Bahamas or the FL keys then put the anchor down and drink beer.
    (27 mini-cruises to the Bamahas, 30 to the keys)
    Now I plan the same on a small power boat and singled out the Albin 28TE as my next pleasure cruiser.
  12. Capt J

    Capt J Senior Member

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    For a few reasons. Plywood may only needs to be painted, but some builders do glass the bulkheads 100% instead of just tabbing them. Coring needs to be glassed on at least one but preferably both sides or it has no strength. BUT the major reason is plywood is much stronger (in regards to holding screws) for mounting all of the various things on them. Think engine room bulkhead, where fire extinguishing bottles are mounted, heavy machinery, etc. The plywood is much stronger at holding things mounted onto the side of it 3/4" side (side loading) , like salon floor resting on it, versus a cored bulkhead that's butted up to the salon floor, then tabbed to the engine room ceiling/salon floor.
  13. Pascal

    Pascal Senior Member

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    True, although coring must be glassed on both sides, not just one, otherwise it will flex.

    You can easily epoxy plywood mounting blocks where stuff needs to be attached and for floors aneasy solution is to epoxy strips of foam core (2"wide works ) to the bulkhead for th edge of the floor to rest on. My only experience is with divinicell but that works very well resulting in a strong light and stiff structure. More time consuming and costly than screwing into plywood but longer lasting
  14. Capt J

    Capt J Senior Member

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    I've seen people re-do center console floors with divinycell and not sure they glassed the bottom side, perhaps they put 1 layer on it before screwing it down to the stringers, then glassed the floor side. Or the stringers supported the floor enough that it didn't flex. I don't know.

    I haven't seen any rotted plywood bulkheads in a very very long time, and only on 1 boat that I can think of. Seen plenty of rotton balsa cored deck issues, once was on a 6 year old boat, we had to cut out the entire fore deck, cockpit deck and swim platform and re-core it. I have been seeing a lot of tabbing broken loose on boats lately for some reason.
  15. Pascal

    Pascal Senior Member

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    Like every thing you need to use the right material and the right amount. A divinicel cored panel with just 2 layers of 10 oz S glass on each side will be extremely rigid and very light but you must glass both sides

    Problem with plywood bulkhead is that the rot will be at the bottom usually in places where you can't. Balsa decks on the other hand will feel spongy right away.

    As a hatteras owner, I know the feeling :)
  16. Bill106

    Bill106 Senior Member

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    As Pascal said, the right material selection and amount are critical to a long lasting part. I've been doing bulkheads exclusively out of Divinycell for over two decades, with a little planning you can easily accommodate heavy equipment mounting by using higher density inserts while making the panel. Especially on cold molded boats, solid bulkheads are not always the best material and can cause hard points leading to delam and tabbing failure at the joints where the hull flex meets a rigid bulkhead.
  17. olderboater

    olderboater Senior Member

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    And right methods and technique for that material.
  18. Capt J

    Capt J Senior Member

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    Just out of curiousity, what coring are you using for the hull? Okuma in the cold molding of the hull or divinycell there also?
  19. Bill106

    Bill106 Senior Member

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    I really don't like Okoume for hull bottom's J, if it's going to be wood, A/B fir is my choice. When foam is the clients' call, I always liked Core Cell for bottoms but switched to Divinycell about 10 years ago. A layer of 18 oz Aramid hybrid followed by two layers of 18 oz biax using epoxy has been working for us.
  20. Norseman

    Norseman Senior Member

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    Sent a message to the owner, via the broker.
    If he takes it to a reputable yard, have all the big issues fixed, with receipts and a re-survey, then I may come back and look at the boat again.
    The broker agreed and will de-list the boat if not repaired.

    In the meantime I was all set to drive up to Stuart and inspect the Cream-Puff
    Albin 28TE listed for sale there, arranged for Thursday morning, but with my luck the Cream-Puff came under contract today...:confused:

    Link above:
    Really low hours though, 272 hours in 12 years, probably not good for the engine, internal corrosion and dried out seals, etc....?
    Any expert comments on that?
    (Without involving idiot and moron labels :D)