Aluminum Kayaks

Discussion in 'Boat Design' started by GAVIOTA, Jun 5, 2008.

  1. Sean Herron
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    Sean Herron Senior Member

    Holy Bunch Of Poo...

    Hello...

    Nice aggressive and purposeful looking fish killer there Jim - I like it...

    I don't get all this hooplah over why you could not make an aluminum kayak...

    All 8 hours of a day I have to fabricate and MIG or TIG where appropriate - little brackets for whatever application to radar towers - and well - boats - or get someone else to do it...:)

    I love aluminum - and if you know how to work it - and you are willing to accept a mil finish - it ends up being the absolute cheapest way to go - one off - at the end of the day - assuming someone else payed for the welder - the wire - and the Hydro bill...:)

    Bunch of Poo heads - if you know how - you can make any damned thing out of aluminum - welded or seam riveted...

    Yeah...

    So there...

    SH.
     
  2. kengrome
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    kengrome Senior Member

    Jim, it looks like you got yourself all worked up over nothing. Too bad you missed my point completely ... :(

    When I said "As far as the concept of building kayaks in aluminum, I think it is faulty from the start." ... I was talking about developing a profitable commercial enterprise based on aluminum kayak manufacturing -- not about one-off aluminum kayak building for personal use.

    :eek:

    I still believe that going into the business of mass producing aluminum kayaks is a faulty commercial concept.

    And OF COURSE kayaks can be built in aluminum. It's been done before and it will be done again ... and I never said it couldn't be done!
     
  3. Bullshipper
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    Bullshipper Bullshipper

    Ken,

    Instead of jumping all over this guy from the start, why don't you give him an estimate of what he needs to get started, your style. What kind of capital it would take to produce an injection mold for a plastic kayak?

    Lets say you get the mold cheap, say a million dollars. It has to be amortorized, so thats about $2,000 in just amortorization per hull for the first 500 units, plus all the other expenses that go into a unit that costco markets for $300.


    You have to start somewhere, and producing a one off that you can sea trail, use yourself, or market IS a viable concept.
    FYI, 50 lbs of 5052 goes for $150.
     
  4. kengrome
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    kengrome Senior Member

    Injection molding is neither my interest nor my specialty. You're probably better off talking with factories in China or the USA, manufacturers in both countries seem to do a lot of this kind of thing.

    In fact, there was a thread last month started by a guy who had recently set up a new injection molding system in the USA from what I recall. You can probably find his thread and talk with him about this if you're really interested.
     
  5. larry v
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    larry v Junior Member

    dont know if its a kayak or not

    This is something that I have been working on for a few years now. After building 27 wooden kayaks I decided to try my hand at an aluminum one. This is what I ended up with.[​IMG]
    So far so good, we have been putting it through its paces. It is a rather large kayak at 20 x 3 ft. but it weighs in at 125 lb.
     
  6. JEM
    Joined: Jan 2004
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    JEM Senior Member

    Wow that is HUGE!

    But only 125 pounds for that size is pretty good. Nice work!
     
  7. kmorin
    Joined: Apr 2005
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    Location: Alaska

    kmorin Senior Member

    Kayak Methods?

    larry v,

    very interesting boat! great stem line and sheer! There were only a few pictures at the link, hundreds less than there are questions in my mind, any additional info on the details of your joints, the metal-alloy? thickness?- MIG or TIG? wire size? weld methods? power supply? Design seems to have a hollow in the bottom's waterline aft? The bottom and topsides seemed full length in one pic then a second pic seemed to show the boat in halves at the master station? But then that [transverse] joint doesn't seem to appear in the final craft??

    The sheer seems to have a riveted coaming or angled section extrusion overlapping the hull topsides to deck seam? Is this seam welded then covered or is the extrusion the basis for the joint?

    The rudder alone would be worth its weight to see more detail and understand how it's rigged.

    great project, thanks for posting your fine looking work, to me this is one of the most interesting projects on the entire site.

    cheers,

    kmorin
     
  8. larry v
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    larry v Junior Member

    Thanks all for the comments.
    This boat is the son of a wooden one that got destroyed when a tree fell on it in a storm. I decided to build with aluminum because the rivers around here are rock bottomed.
    I used as much aircraft tech. as i could in the build (if it was good enough for Grumman, its good enough for me) It took about two years of research and a lot of looking through this sight to learn what i needed.
    Details. 0.050 6061-T6 aluminum sheet and square tube.
    Mig welded and riveted .035 wire 120 volt hobby welder. For thin stuff (below 1/8 inch) these welders do great.
    All the seems are welded inside with a fairly wide weld and then welded on the out side with a thin fast weld.
    The top side is joined with extrusion, just in case i had to get in to do repairs.
    There is a false floor with flotation in it, as well as in the nose and tail. it just holds its own weight when filled with water. (that was a concern when i designed it)
    The rudders are my own design. I have been using them for years on the wooden boats. They are independently operated with foot controls and were designed after watching fish maneuver through the water.
    Most of the pics. are the build process.
    It was a lot more work and time than i had thought it would be. I can build the wood boat in about 40 hours, this took about 100 hours.
     
  9. Petros
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    Petros Senior Member

    interesting design, but it is more like a decked canoe at that size. I consider anything wider than 21-22 inches in a kayak as too wide (it feels like pushing a shoe-box through the water). I would think that it should take a lot of abuse.

    125 pounds does seem pretty heavy. I build skin-on-frame kayaks, light, inexpensive, and fast to build. They typically only take about $100 in materials and about 100 hours (including milling down the wood from larger stock). It uses traditional native construction with lashed joints: they are light, strong and fast. Most weigh less than 20 pounds, the heaviest was about 30 pounds because it had bulkheads, hatches and other accessories. I have built 8 of them.
     
  10. alexlebrit
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    alexlebrit Senior Member

    Origami - and stressed skins?

    I might be barking up the wrong tree here but following a couple of quick experiments, I'm wondering if the thing couldn't be "folded" into shape.

    First off a little mind origami. Take a sheet of standard A4 printer paper, cut this in three lengthways so you have a long thin strip. Now we're going to curve the two long edge up to give a half round shape. and next we're going to pinch in the two endsso they meet. Now without folding down the centre line, fold the two pinched ends in at 45 degrees. If you've done it right you've got something vaguely resembling the hull portion of a kayak. Paper isn't an elastic material and yet we've managed to create compound curves in it without presses etc. I can do the same thing with tin foil, or plastic sheet, or card, none of which strike me as being particularly suited for compound curve making.

    Is it possible to re-create the same process in aluminium sheet? I've only got a small bit of unknown grade ali 1m x 0.5m, in an unknown thckness, definately thicker than 0.05, and I can manage to bend not form this into a nice 2 dimensional curve - it'll spring back to flat after, so I'm tempted to say with a lot of swearing and cursing, and possibly some cuts and abrasions I could repeat my origami on a larger scale.

    If I could, this would give me a hull form from which I could take measurements to make internal ribs and strengthening. From these measurements I could also build a male buck over which to form the next hull, and so on.

    But like I said this is a mind experiment, whether aluminium could actually be made to do this, I don't know, perhaps those with experience would like to say yes or no.
     
  11. larry v
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    larry v Junior Member

    That would depend on your alloy. Once you hit into the 5000 series aluminum they become a bit brittle. If you had a soft chine then you might pull it off. The canoe industry uses a stamping method a lot like what your talking about to form hulls but they normally don't go over 0.063 thick and they use about a 20 tonne press. (i could be wrong on that number) I am not sure one could pull it off by hand.
    If you do succeed let us know.
     
  12. rwatson
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    rwatson Senior Member

    You might like to get a look at Brent Swains book on building Origami Metal Boats - he is a big exponent of the concept.
     
  13. alexlebrit
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    alexlebrit Senior Member

    Oh no, I don't want to build one, it was just a thought, I mean where am I going to get 4m + of aluminium?
     
  14. alexlebrit
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    alexlebrit Senior Member

    Not wanting to tear this thread any further off topic, but, do you think you could explain this a bit more, it sounds like a great way to make a one off kayak.

    PS you can always PM.
     

  15. Grizz
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    Grizz Junior Member

    I see I'm late to the party... but about this statement:

    I would like to see the citation of the CFR that makes this explicit statement.

    That's Code of Federal Regulations. What's the chapter and verse please.

    Grizz
     
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