Buying a hull to start a project boat- another option found....

Discussion in 'Boat Design' started by parkland, May 21, 2013.

  1. parkland
    Joined: Jul 2012
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    parkland Senior Member

    I think I might have found a hull or 2, for sale, and roughly the size I wanted to build a low speed cruiser type houseboat.

    they are both aluminum hulls, double welded seams.
    One is 38" deep, 10' wide, and 40' long.
    Other is 44" deep, 10' wide, and 44' long.
    Roughly 2000 lbs each.

    The bottom plating and motor compartments are 7/64 thick, and the rest is 5/64 thick.
    The company that built them was called "kaizer", but I can't seem to find anything on them.

    These 2 hulls are old but never been built or put in the water, they are just left overs that someone bought and never used.

    I was hoping to get an opinion on these...
    Either one seems like a good option, but I do have a concern, the metal seems really thin.. is it just me? 7/64 isn't even 1/8" of an inch.

    And they are asking for 10,000$ each for the hulls, does this sound reasonable?

    I guess I'm scared I'd buy one, later to find out that something was lacking in he hull design or something?
    What do you guys think?

    What I really wanted is a full displacement style hull, but I'm sure this will work "good enough" with the flat stern design. After all, beggars can't be choosers.
     

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  2. JSL
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    JSL Senior Member

    Could be "Kaiser" as in Kaiser Aluminum. Structure sounds a bit 'iffy' - thin plate (what alloy), An angry fish could sink you. And what is the framing?. The hull is fairly narrow so the cabin would be one level only to maintain decent stability.
    If really old, this might sell at scrap prices, $1.00/lb = $2000.00 After that, it could be good money after bad.
    Suggest you get an expert in to look it over.
     
  3. parkland
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    parkland Senior Member


    Well, they've been sitting for at least 20 years apparently. So they are old.

    I don't know about an angry fish sinking it (lol), but it seems like really light construction for such a large boat, thats for sure.
    It would be a chore building a cabin that weighs less than the hull, haha.

    They're far away, so I have no way of looking at them.
    If we decide this is a great idea, I'll have to hire some local expert to take a look.
     
  4. parkland
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    parkland Senior Member

    The seller says they are marine aluminum, very sturdy, and only 7 were ever built by the company that made them.

    On a scale from 1 - 10, where do I sit?

    10 being "why don't I have one en route already"
    1 being "don't even bother thinking about buying one"
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    Top dollar imo, for a shell, and how slab-sided !
     
  6. parkland
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    parkland Senior Member

    So you think 10,000$ is too high?
     
  7. JSL
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    JSL Senior Member

    Let's see....! -20 years old -only 7 were built - 2 are for sale -$10,000 each
    Using a very rough generic guide, for a properly built hull of this size you could expect around 3000 - 3500 lb aluminum (skiff- finished).
    Until you get a 'qualified' person to assess this 'boat', it's a 0 (unknown).
    And no flare (slab sided).... deduct another point.
    score = -1 = a UFO (unidentified floating object)

    I would not be suprised if these are 'disposables' left over from some commercial/industrial venture such as building a bridge etc. and the seller picked them up at some auction for a good price.
     
  8. Brian@BNE
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    Brian@BNE Senior Member

    If intending to use only in fresh water then its worth doing. You could glue closed cell foam to the hull then fiberglass a skin over that. That would give you both insulation and hull stiffness. Offer less than asking price.

    But if thinking of saltwater use, then imperative to check alloy. There are portable XRF analysers that can do that for you - hire from a mineral exploration supplier/company.
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    An "orphan" thing like this has little resale value, and you need to get it cheap, much cheaper than the asking price imo.
     
  10. pdwiley
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    pdwiley Senior Member

    Scrap aluminium price minus the cost of cutting it up & hauling to the scrap dealer.

    My way of valuing unfinished boats:

    Find a boat or series of boats for sale, in the water and ready to use. This is your baseline value.

    Take the asking cost of the 'project', add to it the cost of everything that it doesn't have that the ready to use boat(s) do have, multiply this by 3 to cater for the stuff you underestimated or plain didn't notice.

    How does the cost compare now? If still less than an outright purchase, start putting a dollar value on your time - it's the one thing you can't buy more of once it's all used up.

    My approach shows that most project boats are very poor value for money, unless you actually want the 'build' part rather than the 'use' part. In fact I've turned down a couple of free hulls because they were too expensive....

    PDW
     
  11. Eric Sponberg
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    Eric Sponberg Senior Member

    Parkland,

    My advice: Walk away and look for something better. From the photos, it is obvious that the framing is not to proper marine standards. The transverse frames "float" above the longitudinal frames--that is, the transverses do not touch the plating. In normal marine construction, the transverse frames are notched so that the longitudinals pass through, and both the longitudinals and transverses are welded to the plating. Even in that situation, plating would likely be more like 3/16" thick minimum, and so 7/64" plating is way too light, even for this construction.

    These hulls were likely built by someone who did not know what they were doing and they are worth only scrap value, as others stated above.

    So, keep your money and go away. These hulls are a train wreck waiting to happen if they get finished into a bona fide boat.

    Eric
     
  12. TANSL
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    TANSL Senior Member

    I can not say that the hull is good or bad because I have no elements to do so.
    What I do I can do is attach a picture, taken from ISO 12215-6 for pleasure boats, which considers totally correct, and normal, using floating frames.
    Not exactly what you see in the pictures of the boat but the floating frames "exist"
     

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  13. Eric Sponberg
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    Eric Sponberg Senior Member

    Yes, I agree they do exist, but in my opinion and in my experience, that is not a good way to frame a boat.

    Eric
     
  14. TANSL
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    TANSL Senior Member

    In my opinion and experience, for small boats, is a very correct method and, possibly, lead to lighter structures and, of course, easier to build.
    Do not forget that in a longitudinal structure the frames do not have much relevance.
     

  15. Eric Sponberg
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    Eric Sponberg Senior Member

    Well, I disagree with that, too. Yes, transverse frames do not contribute to longitudinal strength directly, but they do define the support points for the ends of longitudinal frame segments. The strength, stiffness and sizes of the longitudinal frames depend on the square of the spacing of the transverse frames. Also, the transverse frames determine half the boundaries of the hull skin panels. So in those regards, the transverse frames are extremely important to overall strength.

    As you may know, but for the benefit of the readers of this thread, in any well engineered metal hull structure, the plating comprises about 2/3rds of the hull structural weight, and the frames (longtudinal and transverse) comprise about 1/3rd. If you want to make a hull lighter, you ADD more frames. More frames means the lengths of longitudinals are shorter, the sizes of hull skin panels are smaller, and plating thickness goes down, therefore weight goes down because the hull plating commands so much of the overall weight.

    In the example posted by Parkland, the plating is way too thin for the size of hull and the arrangement of the plating that was there--this just from my observation; it's obvious. So those hulls are not well engineered, probably not engineered at all. I don't think I would ever engineer an aluminum hull with anything less than 3/16" thick plating because thinner than that, the plating distorts all over the place with the welding heat and melt. You have to be a really good welder to keep heat distortion of thin aluminum plate to a minimum.

    Eric
     
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