Any thoughts re: very thin aluminium ?

Discussion in 'Fiberglass and Composite Boat Building' started by SAE140, Jun 23, 2010.

  1. SAE140
    Joined: Apr 2010
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    SAE140 Junior Member

    This post is back-to-front: most people (I imagine) start off with a need or desire, consider relevant designs, and one of their last considerations is actually sourcing the material to build their boat with.

    In contrast - I've got quite a few sheets of thin (0.5 - 0.6mm) ally - salvaged from dismanting a 40 foot mobile home a few years back. Most is flat, but stuff from the walls has a slight corrugation.

    I'd appreciate any brain-storming type ideas of how I might use this stuff to build a boat with. I guess we're talking something around a canoe/ large dinghy size.

    To replace the skin on skin-on-frame perhaps - or laminate 2 sheets with thin ply between .... ?

    Be a shame to waste so much material. Thanks.
     
  2. Landlubber
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    Landlubber Senior Member

    ....if the boat is to be used in seawater, then the standard alloy plate will not be much use, unless you know the grade of the alloy.
    Alloy of the 5000 series (such as 5083) is what is commonly used in alloy boat construction, with magnesium being the alloying ingredient. They then have different tempers, hardness, to suit different applications. 5383 is the latest I believe in wonder materials.

    Back to a simple canoe or dinghy, it would not probably nmatter that much what type of alloy it was made from if you have the stock in hand, just wash it down in fresh water after every use, do not leave any copper wire clippinmgs in the bottom, or lead sinkers, as they will eat holes in it faster than you will believe.
     
  3. apex1

    apex1 Guest

    Lubs,

    he is talking about half a millimeter of Al.

    I doubt there is any sensible way to use that on a boat.

    Regards
    Richard
     
  4. mark775

    mark775 Guest

    On the positive side, tho his address is "Earth", we can quite narrow it down to perhaps the very parish where the boat might be used...
     
  5. hoytedow
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    hoytedow Carbon Based Life Form

    It might make a good roof.:)
     
  6. SAE140
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    SAE140 Junior Member

    Landlubber's caution regarding corrosion is both appropriate and appreciated, but I've already got that one covered. The mobile home from which this material came is one of many thousands which are situated adjacent to the sea and thus subjected to a salt-laden atmosphere. Despite there being no evidence of historical corrosion, I've had a test strip hanging off my tidal mooring for some 2 years now, which shows no corrosion - only a light oxide coating.

    Well - I must confess that I had expected a rather more mature discussion than some of the above rather childish posts.

    I suppose I had expected some novel suggestions perhaps re: laminating these thin sheets with a range of other materials: woven glass matting, thin plywood etc.

    You clearly know little about 'Glare' (GLAss-REinforced metal), which I've actually seen being manufactured, together with the results of test bird impact strikes on the material.

    Kaman Aerospace have been using an aluminum-grp sandwich technique since the 1970's, Beluga aircraft were built using Glare(tm) from 1995 onwards, and more lately the A380 Airbus has incorporated somewhere between 22 and 40 per cent (depending on the source of information) of Glare within the airframe - both in order to save weight and to achieve more structural strength.
    In addition, Glare is the only material currently licensed for use in the construction of explosion-resistant aircraft cargo containers.

    I'd like to think that if an aluminium-glass composite is considered good enough for such aerospace purposes, that something similar might just scrape though as being a material adequate enough to build a kayak or dinghy with ...

    Sources for the ignorant/ sceptical:

    US Patent 5547735 - quote "Aluminum alloy sheets having a thickness of about 0.4-0.6mm are most preferred." "Laminates containing two metal sheets are particularly preferred."

    US Patent 7087317

    http://en.wikipedia.org/wiki/GLARE_(material)

    EP 0 323 60 A1 Akzo Nobel
     
  7. hoytedow
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    hoytedow Carbon Based Life Form

    I suggested roof because trailer siding is very thin and lightweight, making it an ideal material for a small shade, whereas it is so thin it is easily dented or holed if used as a hull. I think 0.5mm is an over-estimate unless you have actually measured it.
     
  8. apex1

    apex1 Guest

    Unfortunately it is not as easy as you may assume.

    Your Al sheets have just not enough beef, therefore zero value in boatbuilding structures. So far the facts.

    Now to the dreams:

    Reinforcing metal to provide the properties required is the weirdest idea one could come up with.

    Reinforcing wood or glass is another animal, and would make sense. But adding a paper thin Al layer makes it just heavier not stronger.

    Aircraft materials btw. are NOT seawater resistant, they have other properties, like higher fatigue resistance for example.

    All in all, be clever and sell it as what it is: scrap metal.

    Regards
    Richard
     
  9. Landlubber
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    Landlubber Senior Member

    All in all, be clever and sell it as what it is: scrap metal

    ....do tend to agree........anything else is really just being pig headed determination to prove different....if you think about it, it really is quite useless.....
     
  10. Guest625101138

    Guest625101138 Previous Member

    When you have a name as a grade of oil and location earth you have got to be in here for a laugh.

    If you are being serious it is possible to build a boat with that size sheet. I have a few made from a single thickness of 0.6mm sheet. If is it in good eb nough condition to sanwich construction foam then you could make a reasonable robust lightweight canoe.

    I have a few photos of prototype hulls I have made using thin sheet.

    In the end there is a good deal effort preparing and you need to decide if you want to spend the time doing this and end up with something les than ideal. If you are time rich and cash poor then it might be a way to get out into the local river.
     
  11. pistnbroke
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    Well I did use 4 sheets of thin steel shed cladding total 6m x 2m and bent it to a boatshape ...cut the bow stitchand glue style and a ply transom and used it as a mould to make a fibreglass canoe.....would not do it again too heavy and costly should have used ply....
     

  12. bearflag
    Joined: May 2010
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    bearflag Inventor/Fabricator

    http://www.tgdaily.com/trendwatch-f...posite-stronger-and-lighter-than-carbon-fiber

    I don't get the haterade on this subject. As with any material, if it is properly engineered it could be a win. Fiber Metal Laminates have some really exciting properties, and as noted may have some construction/cost/material advantages over other methods.

    Its my understanding that one of the main advantages of FML's is that you gain effectively unlimited fatigue cycles, and mechanical properties similar or superior to glass/aramid/carbon fiber based materials.

    I am envisioning a high speed light weight racing catamaran or something that has formed aluminum panels that are glued together sort of like a Lotus or a Ferrari, except these panels are actually a bonded glass/carbon/metal matrix.

    One particularly interesting note is that many of these materials are thin and spring-like, so you would loose much of the rigidity of say a foam sandwich construction, but this could be restored by geometry. Since the fatigue cycles are high you might be able to get by with a surface skin with a lot of flex. (esp if it was very strong in tension and returned to its prestressed state).

    Regardless I encourage it.

    Burt Rutan started Scaled in a garage, so did North Sails, and practically any other company worth talking about.
     
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