Attaching a Steel to Aluminum

Discussion in 'Metal Boat Building' started by Hotel Lima, Oct 14, 2007.

  1. Hotel Lima
    Joined: Sep 2006
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    Hotel Lima Junior Member

    Hello again,

    What is the best method of attaching a steel hull to an Aluminum superstructure? I understand that is this very tricky business.


  2. Wynand N
    Joined: Oct 2004
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    Wynand N Retired Steelboatbuilder

    I have read somewhere of a strip you do it with - one side you weld the steel to and the other side the aluminum.....seriously
  3. MikeJohns
    Joined: Aug 2004
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    MikeJohns Senior Member

    Wynand the manufacturing process is called explosive bonding.

    All the strips I have seen have been stainless steel on one half and alloy on the other. The last time I looked here it had to be made to a minimum order and cost an arm and a leg. A neat solution though particulalrly for plating.

    The less costly way is to gasket, fully isolate and bolt both framing and outer plating.
  4. waikikin
    Joined: Jan 2006
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    waikikin Senior Member

    Hotel Lima, on lage vessels an expansion joint or a few are also required & incorporate a simple bellows glued in for water integrity, I only know cause I glued some in on warships, as Mike says there was a gasket in the connection to deck upstand & thousands of bolts all with fibre washers & probably sleeves through the holes too.Gluing in the bellows was kinda awkward as the joints set inside the deck & house line & heaps of wedges & batens required to maintain contact while the adhesive set. All the best from Jeff.
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    A DeltaStrip and DeltaCouple are Dupont products that are steel and aluminum strips, explosive bonded to an inert center section. Weld the steel to the steel and the aluminum to the aluminum. Another method would be weld stainless flanges to the mild steel and bolt the aluminum to this with an isolator.
  6. SaltOntheBrain
    Joined: Feb 2007
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    SaltOntheBrain Senior Member

    I think I remember a product called Al-Clad. It was plate steel on one side, aluminum on the other. Make the whole deck under your superstructure out of it. I will post up if I can reach my old boss to ask for more info.

  7. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    Dont complicate this. Build hull of Steel, superstructure in aluminum with base that bolts to hull with stainless steel 316 nuts and bolts. Oh, I forgot to mention isolate AL from Steel via a gasket of epoxy or polyurethane sealant as gasket. AL is not touching Steel. Paint aluminum structure to prevent any residual steel corrosion from jumping up to AL.
  8. Eric Sponberg
    Joined: Dec 2001
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    Eric Sponberg Senior Member

    We use Detacouple on the Moloka'i Strait motoryachts and it works like a charm. This technology has been around for over 30 years. Our builders buy it with A36 marine grade milde steel on one side, and 5083 or 5086 aluminum on the other side. The oustide surface is sealed with epoxy filler and paint to keep the marine environment away, and on the inside the surfaces are covered over with polyurethan foam. I have never heard of a Detacouple failing.

    In Europe, the trade name is Tri-Clad.

  9. Etec
    Joined: Oct 2007
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    Etec Junior Member

    yup...i've use triclad to built aluminum superstructure and steel deck.
  10. mastcolin
    Joined: Jun 2005
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    mastcolin Senior Member

    Loads of superyachts are ally superstructure with triclad join to steel deck/hull. It's no big deal.

    The easy option is the bonding option though for smaller jobs I imagine.

    To continue another thread, go the whole hog and build your sundeck/bridgedeck/flybridge in composite and bond that to the ally...stick the teak to everything:)

  11. sarikawong
    Joined: Jan 2008
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    sarikawong New Member

    Great thread!!!
    And thanks for all your ideas.....
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