Thin sheets of steel and Sikaflex Adhesive

Discussion in 'Boat Design' started by mustafaumu sarac, Aug 15, 2021.

  1. mustafaumu sarac
    Joined: May 2017
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    mustafaumu sarac Senior Member

    I read few archived posts on boatbuilding with thin sheets of steel and sikaflex adhesive.
    Could you please tell me what is the thickness of steel sheets , how many layers and which model of sikaflex been used ?

    Do I need to cut with laser and how many meters of boat been thinked for this process ?

    Can you please explain the process little bit ?
     
  2. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    What are you planning to build Mustafa?
    Will it be used in fresh water or salt water?

    Steel is a VERY strong material - in theory you could probably build a boat out out 1.5 mm thick steel. But it would not have much of a margin for rusting and corrosion. Hence one reason why steel plates on boats are much thicker than they theoretically have to be.
     
  3. mustafaumu sarac
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    mustafaumu sarac Senior Member

    Hello bajansailor,

    I am thinking for long sea passages.

    I know tomthumb 26 is 3mm thick. Can you confirm it can be built by 1.5 mm thick steel for only single summer voyage ?

    And I want to learn can I use sikaflex instead of welding and which sikaflex ?
     
  4. bajansailor
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    bajansailor Marine Surveyor

    You do not want to go below 3 mm thickness, even if you can find a good way of gluing thin sheets together.
    You do need that extra margin of safety against corrosion - and a 3 mm thick plate will also have a lot more stiffness than a 2mm or 1.5 mm plate.

    And as for gluing the sheets together with Sikaflex - what happens when (not 'if') some rust gets under the Sikaflex?
    The joint will fail, and you will probably sink.
    If a welded joint rusts, it will take a long time (relatively) before it finally fails.

    You said
    Do you want to build a 'disposable' boat, re how it will only be used for one summer (or one voyage even)?
     
  5. mustafaumu sarac
    Joined: May 2017
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    mustafaumu sarac Senior Member

    Hello Bajansailor,

    Yes, I am thinking an disposable boat which every part would be lightweight but again steel.

    I dont want to build structures for crane and lots of heavyweight clamps.

    I am thinking a 4 meters long boat.

    I am thinking to cut long wide strips from thinnest steel and I want to bend the out of use parts of steel one on other , two large areas will be adhesived. If the corrosion begins , it will take too much time to invade all adhesived area,

    I want to learn what is the thinnest steel I can use ? 1.5 mm is sounds good but again what do you say ?

    This boat could be build even thinner steel sheets like cold molding but what do you think ?
     
  6. bajansailor
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    bajansailor Marine Surveyor

    It takes the same amount of time and effort to build a 'good' boat as it does to build a 'bad' boat.
    So if you really want to build in steel, you might as well build a 'good' steel boat, that will not be disposable, and will last a lot longer, and be much safer.
    Ok, the materials will cost a bit more to buy initially, but you will still have a boat at the end of the summer, ready for more adventures the following summer.

    However I think that you would be better off in every way imaginable if you build your 4 metre long boat from plywood or fibreglass instead.
     
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  7. mustafaumu sarac
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    mustafaumu sarac Senior Member

    Which sikaflex model adhesive steel sheets one on other ?
     
  8. bajansailor
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    bajansailor Marine Surveyor

    I don't know - and I stand by my comments in my previous post.
    Maybe somebody else can offer an opinion - but I doubt that very many people on here think that your plan is a good one.
     
  9. messabout
    Joined: Jan 2006
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    messabout Senior Member

    1.5 mm steel makes the boat similar to a tin can. It will dent easily, it will not have adequate stiffness to hold its shape unless you add a lot of interior bracing. The need for all that bracing makes the whole project labor intensive. Sheet metal that thin poses the hazard for cutting flesh. 1.5 mm sheet metal will weigh about 2.5 pounds per square foot..... about 12.5 KG per meter square.

    Bajansailor has advised you wisely. Use plywood and epoxy. You will have a much more suitable boat than so small a steel boat would make. The wooden boat has the advantage of positive buoyancy where steel would sink immediately. I suspect that in the end the plywood boat would cost less to build and it would surely have more re sale value. A simple stitch and glue ply boat will suit your purposes, your budget, your safety, and take less time to build. In addition the wooden boat is much more comfortable in terms of heat or cold weather. And the ply boat will not be as noisy as the tin can boat.
     
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  10. BlueBell
    Joined: May 2017
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    BlueBell "Whatever..."

    3m 5200 will work or Sika 117
    Can you get either of those products Mustafa?

    What type of steel are your 1.5mm sheets, or are they scraps?
    Do you know the type of steel?

    Where have you been?
    Haven't seen you here for a while.
    I kinda miss you...
     
  11. mustafaumu sarac
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    mustafaumu sarac Senior Member

    Hello Bluebell ,

    Thank you for your kind words. I am istanbul and here , there is huge sika presence.

    I sent another thread and stainless steel rolls or marine grade aluminum rolls are hopeful.

    I thought little bit and I will make the outer skin with marine grade AL - 2 X 0.5 mm thick cold molded- and internal will be thick GRP like Airbus aircrafts. This would be lot lighter , longer life and lot cheaper.
     
  12. mustafaumu sarac
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    mustafaumu sarac Senior Member

    thickness ................wideness......................int.dia........................,out.dia.
    0,18 - 1,00 mm.........21 - 500 mm........ 300 / 400 / 508 mm ...........1750 mm maks.
    ALUMINUM STRIPE ROLLS
    5000 OR 8000 ALLOY
     
  13. Squidly-Diddly
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    Squidly-Diddly Senior Member

    I'm thinking Sikaflex would not be good for this.Learn to Calculate How Much Caulking or Chinking You Need — The LogFinish Log Blog https://www.logfinish.com/blog/2016/07/learn-to-calculate-how-much-caulking-or-chinking-needed/

    Note how backer rod is used to keep caulking a thin profile so instead of pulling off one side because the caulk is so strong internally, the thin caulking is able to stretch a bit and maintain the seal.

    But if all you've got is a pallet of Sikaflex and stack of steel, I'd make sure all oil/grease is off the metal (almost all metal with come with some oil from rolling and preserving) then give it good roughing with 60 grit or other rough sandpaper.

    I'm also thinking MAYBE several thin beads of caulk-as-glue will be better than one wide field of glue, but not sure.
     
  14. BlueBell
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    BlueBell "Whatever..."

    You know who has all this information Squidly?
    The manufacturer, Sika.
    Have a look.
     

  15. Squidly-Diddly
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    Squidly-Diddly Senior Member

    without looking, I'm pretty certain their only info will be "Do NOT use this product for other than intended use as caulking in buildings and do not use underwater".

    When I was building jails we used special "pick resistant" caulk that was like Sikaflex on steroids. It came with little can with a brush in the lid of some thin "primer" we were supposed to smear on surfaces prior to application with all sorts of dire health warnings. Stuff seemed to work about same without or without primer.
     
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