The good, the bad and the ugly - Steel building methods that is....

Discussion in 'Metal Boat Building' started by Wynand N, Aug 18, 2010.

  1. Wynand N
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    Wynand N Retired Steelboatbuilder

    That said, lets start the thread and let me the first ;)

    Steel boat building may be any of the following methods;

    1. Chine - hard chine, multi chine and radius chine

    2. Round bilge

    3. Framed

    4. Frameless

    5 Origami

    Which is best and why? Pros and cons of different methods? Or any other query concerning these methods - please lets speak our minds within the preamble spirit of the thread.:)
     
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  2. terhohalme
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    terhohalme BEng Boat Technology

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  3. magwas
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    magwas Senior Member

    It depends, as always.

    I like origami. It is an ingenious technique well suited for the home builder.
    Yes, I have read the transverse frame and the origami threads, and I hope no one will bring that style of conversation here. My conclusion is that origami is indeed suitable for up to 30-40 foot. Yes, I would not build anything above 20 ft without proper calculations, but I understand those who sail Brent 36s. It is a proven, sturdy boat in spite that the designer refuses to use any scientific method to prove it.

    disclaimer: I am not qualified to have an opinion on the subject, as I have only drawn origami boats, and made models from paper. I am in the process of building my first real one, and it is still not steel but flax composite.
     
  4. Wynand N
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    Wynand N Retired Steelboatbuilder

    Magwas,
    I agree with you that origami has its place with the home builder provided that is is well engineered.
    Not everyone is a boilermaker or welder out there and this type of construction will suit their abilities.

    Personally, I would go for a "frameless" v/d Stadt design. Relative modern lines, build very fast, although more welding on the hull is needed. All panels are computer generated and easy to layout. In short, the plates are also pulled together and the boat takes its shape - much like origami, albeit on a different scale.
    However, I believe there are also other frameless designs out there from other well known designer worth the effort, although I had not build any of those.

    This said, Im not suggesting that origami must be rejected for the conventional frameless design - both have their merits. Just a matter of personal preferences.

    My only pain with origami is that no proper calculations are done that Im aware of and safety compromised because of the lack of this.
    Perhaps someone out there has a set of origami lines and we can try to convince MikeJohn's to do us a stress analysis on that and calculate a scantling for it and provide origami followers with a safe set of plans....

    Terho, nice pics, why do you not post it here and we can all discuss it?
     
    Last edited: Aug 18, 2010
  5. magwas
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    magwas Senior Member

    I think lack of calculations is not inherent to origami. More exactly there _is_ a little difference between lines and actual build, but I think it can be covered with appropriate safety factors and maybe not much greater than the other differences natural to each building methods.

    I would be very happy to draw up lines for a cruiser in the 10m (32ft) range. I can do the drawing, but I need criticism, much like in the http://www.boatdesign.net/forums/boat-design/placement-seat-kayak-34186.html thread.
    Anyone offering that?

    (Actually I have offered this (with something above 40ft) to Brent to take MikeJohn's offer with my drawing, but he refused.)
     
  6. waterdrop
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    waterdrop Junior Member

    You know I've browsed these discussions about these brent's boat designs and I'm no engineer and so don't really understand exactly what you mean by scantlings or a stress analysis, I mean obviously there are forces put on the boat in some what predictable ways when sailing and uhm.. when grounding and the design comes into how the forces are spread over the hull.
    The origami technique in my mind is a great, fast easy way to build a nice fare shape, reduce welding time and distortion and skill requirement and is ideal for the amateur, how many frames one welds in after is really the issue it would seem so it's really just frameless part that in debate. Myself I'd be happy just because it 3/16 steel and certainly no worse than fiberglass or wood and maybe even aluminium when you hit something, in fact better usually. The debate here is really how the forces are distributed along the hull when you hit something (am I wrong here) I've never seen a lines drawing for any of brent's boats but you don't really need one as you needn't do the lofting that is normally done in a build.
    So in the 20' - 40' foot amateur homebuild what would be an acceptable way to do it as easily as the frameless origami technique?
     
  7. welder/fitter
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    welder/fitter Senior Member

    I find the plating-before-framing method interesting. I re-read Michael Kasten's comments on various methods - thanks for the reminder, "Apex" - and went through the Van de Stadt site, again, this time taking a closer look at the Norman 40. What other sites/boats built in this method can people recommend? (sail, 35-45feet, pilothouse are my preferences)

    Terho, I really like the origami model you posted pictures of on the other thread. do you have any photos from the aft perspective? The centreline looks as if it wouldn't be as tortured a seam as with the type we see on the west coast of Canada. Will you be taking it further, or was it just to show how simple it was to design? Overall nice shape!

    Mike
     
  8. Wynand N
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    Wynand N Retired Steelboatbuilder

    I had seen a 34ft v/d Stadt 34 buckled its side decks and sheer from the pull exerted on the chainplates when the mast went into compression.
    BUT, this boat was also built by an ignorant home builder that thought the scantling (reinforcing) by the designers were not necessary and done his own thing......:eek: and payed the price in a real blow.

    Scantling is basically put the supportive members fitted to a frameless hull to support hull plating (panels) and to handle loads imposed on the boat.
    In conventional boatbuilding the scantling is the framework before plating.

    Think about this: A very well known designer in steel once told me the hull plating is only necessary to keep the water out of the boat - perhaps this just nicely sums it up;)

    Elsewhere an argument in the making about how a pipe mast can penetrate hull plating. Steel is not so strong as commonly believed when a sudden force is acting upon it.
    I saw a 6" steel nail embedded halfway into a big universal steel column (12mm plate) after an explosion.....
     
  9. pdwiley
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    pdwiley Senior Member

    As I've said elsewhere, you have to consider kinetic energy and momentum.

    Drop a 40 gr piece of lead on 5mm steel and it bounces off. Lay it on the surface and smash it with a large hammer and it smears out to a thin paste.

    Wrap it in gilding metal and accelerate it to 1000m/s and it punches a neat round hole all the way through.

    I have instrumented data showing a four-fold increase in load due to dynamic movement such as ship pitch & roll. It is this sort of thing that a simplistic statement about static loads and tensile strengths don't take into account.

    There are a few VDS Normans around here but I simply don't like the lines. This is a statement of aesthetics not engineering or function.

    A couple of observations about the skin first build.

    You need to be able to get plates of suitable size or you've a lot of butt welds to do and unless you can flip the plates, those butts are only going to be from the upper side. Good potential for distortion there.

    The hull plate is going to be thicker than a frame first boat, almost certainly. That weight is spread out over the entire length of the hull so the boat will be less buoyant on its ends.

    Getting the hull together may be quicker but adding frames to the curved surfaces outside the midships area is going to be a lot more fiddly. You now need to make templates of each piece, take that template out and cut the steel, then cart the steel frame segment into the hull and weld it in place. I can see this being a major PITA with a LOT more climbing in & out.

    I find to my horror that I like building big stuff so I doubt the boat I'm building will be my last. If there were an origami design close to the 12m mark, with acceptable scantlings, I'd be very tempted to build one, just because I could. I'm about to start plating out my hull, after which (provided I don't go interstate for a while) fitting out won't be much of a challenge. After building 3 houses there's not much in the way of wiring, plumbing and cabinet work that I can't do.

    PDW
     
  10. Northman
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    Northman Junior Member

    Wynand: that is a great idea! I hope everybody contributing here respects your preamble. Is it possible to make your first post a "sticky note" - something like "please read before posting"? I hope the moderator shows a hard hand from the very beginning and the thread a long and constructive life.
    Walter
     
  11. welder/fitter
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    welder/fitter Senior Member

    What I'm looking for is a design that I can get a first-time crew up to speed on. Eventually, I'd prefer to go with radiused hulls and if I were doing the actual work myself, I'd go straight to radiused hulls.

    The plate-first method does seem to reduce hull assembly time. I'm not sure about your suggestion that the plate would have to be thicker, based on the sites I've viewed(Boden, Dudley Dix, Van de Stadt, BRoberts). From what I've read, in each case, the jig(trestle) design is given, as well, so there doesn't seem to be much guess work. I just figured that a relatively quick build before moving to a more challenging build would be wise. I really don't want to spend more time than necessary on the first one, as it will probably be the first build for most involved(& I'll be paying an hourly wage!).

    I'm not overly stoked on the pilothouse windows of the Norman40, nor the pilothouse exterior aesthetics, for that matter, but modifications could be made. I like the idea of a specific design that offers both round & multi-chined options. Anyway, I'm wide open to all suggestions.

    LOL I haven't sourced the maximum plate size available where I'll be building, never even gave it a thought! I was able to get pretty large sheets before, but that was 17 to 19 years ago!

    Mike

     
  12. Northman
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    Northman Junior Member

    Me too.

    That's what I'm looking for, too. In the Norman 40 I find the accomodation a bit cramped - not enough space to sit on the bed in the aft cabin - and I want a skeg-hung rudder. Actually, a transom-hung rudder would be my first choice.
    I recently stumbled over the homepage of Dennis Ganley that after his death now is maintained by his daughter: http://www.ganleyyachts.co.nz/. I found some of his designs quite interesting. Some are build with a single chine which would make for little welding. There is a very attractive boat on Yachtworld: http://www.yachtworld.com/boats/1998/Dennis-Ganley-Time-Rider-1199477/Auckland/New-Zealand, unfortunately with the pilot house in plywood, not steel.
    If anyone has an opinion about Ganleys designs I would be very interested to hear.
    Walter
     
  13. pdwiley
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    pdwiley Senior Member

    I looked at what I was told was a Ganley 'Hitch-hiker' design last year. While the build left a fair bit to be desired, the lines were nice and room in what was a 28' hull was excellent. This one had survived a heavy grounding that dented in the port side hull midships along the chine, but there were no leaks. I would have bought this one except someone else put a deposit on the day before me. It was a cheap buy because of the damage.

    PDW
     
  14. pdwiley
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    pdwiley Senior Member

    OK, the plate thickness comment was aimed at the flat plate pulled together technique that Brent uses. If the plate is too thin it's going to buckle, big-time. I like the idea of this system but until there's engineering data on what framing needs ot be added after the hull is pulled together I won't build one.

    I've seen a 34' VDS built here in 4mm using the female mould technique so no problems there. I'd expect the same for the other designs.

    On plate sizes, locally I could get 6m x 1.8m plates at $72/m2 or I could get 3m x 1.8m plates from the mainland at half of that. Freight isn't that much. Both are in hot rolled so need blasting & priming at quite a bit of money. No such thing as blasted & primed plate that I could find, even pickled & oiled was impossible if you wanted sheets over 2.4m x 1.2m. I'm sure it could be obtained somewhere, but not from the local merchants. I tried.

    Blasting & priming is damn expensive. I've chosen to only build with primed steel so I can avoid blasting inside & out at the finish. I bought a 120 cfm air compressor so I can do some of my own blasting but I still prefer to farm it out. This may change in the future.

    The single chine frame-first design I'm building is going together nicely and I'm happy with it. As I've never built anything else I can't compare the build speed with other methods.

    Point is, you need to consider what materials you can get at what price as well as the design if you're building on a budget.

    PDW
     

  15. Wynand N
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    Wynand N Retired Steelboatbuilder

    Since vd Stadt is mentioned a few times and so the 40 "Norman", have a look at this pic.

    My first boat built professionally in 1988 that happens to be a 34ft Stadt with a Norman deck. This was a once off boat and wonder if such a feat was done elsewhere.
    I had the 40ft Norman plans available for a future boat and my client was sold on the Norman, but he had only a 34ft budget. So I made a plan :idea:

    When I checked the drawings, I was surprised that the 40 Norman hull was virtually a scaled up 34ft. So a few calcs was done and got a multiplying factor to scale the deck down and built a 34ft Norman..:cool:

    On plate thickness, here are some boats I had built;

    Tom Thumb 24 & 28 - Hull 3mm, deck 3mm - frameless
    Dix 30 - Hull 4mm, Deck 3mm - radius chine over frames
    vd Stadt 34 & 40ft - Hull 4mm, deck 3mm - frameless - multichine
    Dix 38 - Hull 4mm, deck 3mm - radius chine - I commissioned this design in 1991
    Adams 40 - Hull 5mm, deck 3mm - round bilge over frames
    Dix 43 - Hull 4mm, deck 3mm - radius chine over frames
    Roberts 45 - Hull 5mm, deck 3mm - multichine over frames
    Dix 57 - Hull 4mm, deck 3mm - radius chine over frames
    Dix 65 - Hull 4mm, deck 3mm - Radius chine over frame
     

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