STEEL HULLS with Composite Superstructure / Topsides

Discussion in 'Boatbuilding' started by brian eiland, Jun 16, 2013.

  1. brian eiland
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    brian eiland Senior Member

    Of the metal choices I chose steel. It is the most ductile (damage resistant), and it is relatively cheap. If you look at these two photos don't you see a lot of relatively flat panels, and/or minimial curvature panels. Or look thru the construction photos on the Euroships website. Both the hull and the superstructure can be built of relativly flat panels, particularly with a hard chine hull.

    So alum is out....not suitable, not necessary

    There has been mentioned plywood for both hull and superstructure. Yes it might work very easy here, BUT it is then 'classified' as a wooden boat. That makes problems if someone buyer wants to finance a purchase (many loan institutions no longer make loans on wooden boats, many insurance companies no longer insure wooden boats, and a number of marinas will no longer offer dockage (long term) to wooden vessels.

    So wood is out...not 'marketable'

    Steel makes more sense for the hull than does composite. And I think some sort of composite makes more sense for the superstructure than steel.

    Which steel?....nothing fancy, just pay attention to protecting it's bilge areas properly.

    Which composite?....that remains to be determined, but some sort of 'panel' construction seems to make the most sense to me.
    Decks?....could be steel or composite
     
  2. brian eiland
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    brian eiland Senior Member

    The Exocet missile which hit Sheffield did not detonate, but the missile severed the high-pressure fire main on board. The resultant fire caused by burning propellant ignited diesel oil from the ready-use tanks in the engine room, and other inflammable materials used in the ship's construction. These fires burned unchecked for a number of days after the ship was abandoned.

    And the superstructure was steel, not alum....I didn't know that
    http://en.wikipedia.org/wiki/HMS_Sheffield_(D80)
     
  3. michaeljc
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    michaeljc Senior Member

    Can you elaborate why you consider aluminium to be 'not suitable, not necessary' ?

    Have you done a costing on AL vs Steel? Where will this craft be built?

    Are designing for fresh or salt water?
     
  4. michaeljc
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    michaeljc Senior Member

    When I look at the above photo it becomes apparent why steel is probably the best hull material. There are a lot of distortions below the rub rail which is probably due to impact with canal banks. In canals there is also the possibility of debris etc.

    I am not sure I would agree with 'any old steel' The design I looked at was about 60', 60ton with 5 mm steel hull. Why not 4 mm corten?
     
  5. Titirangi

    Titirangi Previous Member

    Brian, your thread was about the use of suitable lighter material for superstructure construction on a steel hull, now you decide to go with steel.

    What happened to your original objective???
     
  6. brian eiland
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    brian eiland Senior Member

    Aluminum....'not suitable, not necessary'

    First off aluminum is considerable more expensive than ordinary ship building steel. And the equipments and techniques to work on this material are more sophisticated as well.

    If alum is dented it cannot be simply heated and contracted by into shape. Ask any race car or specialty car repair guys about working on alum panels. Steel can be contracted back into shape with a little heating and hammering.

    If you intend to maintain a nicely painted alum vessel (rather than a raw Dashew look), you will find it particular challenging to get the proper etching primers to use. And if you use any copper based anti-fouling paint you must contend with various barrier coats and electrolysis considerations,,....this pertains to thru-hull fittings as well since most are dissimilar metals. I ran a 60 alum Chris Craft for a few years.,...give me steel's problems instead...any day.

    And what would be the reason to chose aluminum in my cases,...to save a little weight. I don't need to save weight in the hulls on these 3 vessels I'm working on.

    Give me a steel hull when I accidentally come in contact with a corral head or a reef in the Caribbean or out in a remote island in the Pacific. Give me a steel hull when I'm invariable banging into pilings, bulkheads, etc as I trawl thru the inland waterways on my canal boat.
     
  7. brian eiland
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    brian eiland Senior Member

    i'm not a steel expert as I've stated, but I have read that some owners were unhappy with the choice of Corten steel.....I forget why?

    Just found a good reference by Wynand
    http://www.boatdesign.net/forums/boat-design/steel-hulls-31264.html#post340662
     
    Last edited: Jul 6, 2013
  8. brian eiland
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    brian eiland Senior Member

    Sorry I don't see where I have changed to a steel superstructure?

    I might consider steel decks, but I don't really want them if there is a reasonable alternative.
     
  9. brian eiland
    Joined: Jun 2002
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    brian eiland Senior Member

    Steel Hull Prep and Maintenance

    While looking thru a few 'steel hull discussions' I ran across these three references on this one page here:
    http://www.boatdesign.net/forums/metal-boat-building/4mm-steel-hull-1930-2.html

     
  10. brian eiland
    Joined: Jun 2002
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    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

  11. brian eiland
    Joined: Jun 2002
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    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

    Poyurea Coatings

    I remember posting some VERY interesting videos on these new coatings, but I couldn't remember the name of the stuff. Does anyone on the forums have any personal experience with this coating?....looks dynamite !!

    http://www.ace-dragon.com/Polyurea_Coatings.html
     
  12. Titirangi

    Titirangi Previous Member

    Look up RHINO coating - extremely tough elastic polymer coating used originally to seal polyurethane closed cell foam fenders and harbour buoys.

    Common use is tipper truck and boggy bodies to protect against wear and impact. Only issue is difficulty successfully removing the coating for weld repairs.

    Working with Bayer I found a lower cost alternative hot low pressure spray application (to RHINO) for coating pilot boat fenders.
     
  13. Titirangi

    Titirangi Previous Member

    The polymer layer on test section was hydraulic pressed with 3" dia pin @ 600kg to fracture the coating.
     

    Attached Files:

  14. brian eiland
    Joined: Jun 2002
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    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

    Attached Files:


  15. Titirangi

    Titirangi Previous Member

    Good article, covers a big issue we had to begin with both applicator and finish on first projects.
    Humidity levels combined with low winter temps caused blistering and peeling from PU substrate until we realized with our own research what was causing the problem.
    The applicator guy was at point & squeeze the trigger level of product technical knowledge.
     
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