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. rugludallur
    Joined: Jan 2006
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    Location: Iceland

    rugludallur Rugludallur

    Send it, who needs to send it when it's trailerable:


    But since it's in Iceland the shipping would be something like $20.000 :rolleyes:

    Mechanically these aren't that hard to build, it's mostly the electrical side of things because of interference from the plasma arc. The mechanical only took us around one year, rest of the time was spent trying to debug interference and electrical issues.

    1 person likes this.
  2. durp
    Joined: Mar 2017
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    Location: Puget Sound

    durp New Member

    I know this is an old/ dead thread, but it has brought up some very interesting points that I am hoping to have clarified.

    1) Does anyone have a pdf of the yago project book or plans? I am very interested, but it seems to be dead. I would LOVE to have this booklet for my collection.... (main thing I am looking for here right now)

    2) Building a 36ft boat, completely outfitted could be done for $50k, sure, but this will mean you will be buying mainly used gear. IMHO you may aswell get some good stuff that already comes bolted to a hull, unless you just really need to build it yourself. In the USA, there are so many stellar deals on boats that owners just want to have gone, just wait till its been on the market over a year before making an offer. ;) You can shave a load of time and money from the project by living close to the bone and doing away with unnecessary luxuries. Most 20- 30 somethings will be fine with this, but the geriatric sailing society will throw a fit without refrigeration, hot water, roller furling, shower, water maker, radar, chart plotter, and can't be bothered with emptying a composting head. Then again if you worked your whole life to try and do something cool, but got old and broken instead of living in your youth, you would probably demand such comforts as well, in the small chance you actually got it all to work long enough at the same time to be confident to cast off. If you are young and want adventure, people used to sail from South America on green balsa lashed rafts with square sail to Polynesian. Was it comfy? Not as much as a fine 60 footer, but it could still get the job done if you were young or crazed enough to be determined to set off do or die style. I guess the point is it costs exactly however much money you have to put together a boat, regardless of your personal wealth.

    3) I have been welding for money since I was 14 although I would not call myself a pro. I have built roll cages for race cars, repaired heavy machinery, and done a lot of fabrication. Building a full scale boat with no experience is a fool’s errand, and you will not be happy with your monstrosity. That being said, my old man always says you can get good at welding and cutting, or grinding. Just start small. First build a shoebox sized model or three to scale in your preferred method. After you knock that out of the park, build a dinghy, and if you are still into it build a full sized boat. You will save the most money and time by practicing instead of being a dingle berry jumping into a massive undertaking.

    4) Hulls are the quick part of the boat. After working my way up in size to larger and larger refits/ restorations, I can almost promise you I would much rather just build a hull then do all the other work that turns said hull into a boat. Rigging, building sails, interior carpentry, ect ect ect, is more time consuming. Hell, it takes me longer to do a nice refinish on my dinghy then it took to build it, and it is just a 10.5 ft row boat!

    5) Being a total book nerd (I own originals of Lee Woas sailing without a wind vane, Bill's How to build a wind-vane, pretty much every AYRS pamphlet ever put out, the Pardy's, Hiscock's, and many other classic gems.) I had to leap at the chance to get my hands on a copy of Brent's book. Gotta say, I think the math and theory may be a bit muddled, the welds in the pictures are not of my standard, but there sure are a bunch of his boats about, and every owner I have met loves them. This is the boat I would build if I was keen to follow Van Loans rig advice with a schooner junk rig, truly a "hammer and nails" approach. I wholeheartedly believe you can build a seaworthy boat using nothing but steel, basic tools, his book, and your own intuition. I would not go much over 30ft - 36ft if using such style, but you need no plans at all to build these things if you have any level of mechanical or fabrication aptitude! Truly, the **** looking welds are just more encouragement. I saw them and was like, damn, I KNOW I can lay a better bead then that, and there are a bunch of folks sailing around in these things. It is a fact people have had success with his vessels. I do not think it is cost effective for a minute to build one in the USA, or probably anywhere in North America. We just have too many good used boats that could be modified to be more seaworthy for less than the cost of building any boat. If I was some oppressed person in some part of the world with less resources yet I was determined to learn boats and get on the water to voyage (or seek freedom), this would be the book. Heck, it might come in useful if I sink my current boat in some far off place. Seriously he even lays out the shape, scale it to whatever size that will fit your material. Don't get me wrong, I have no plans, but based off of my personal belief that all DIY boats should have structural bulkheads anyways strength should be just as good or better as any production boat of similar size. This is undoubtedly a way to build a little bruiser, but with all things the execution is what will dictate if it lasts. Everyone has to admit that for $20 plus shipping you are getting a bargain. You can use this book to bang out a boat with a crew of 5 in Asia in less than a month no doubt. Can you name any other plans that can get you out of some far off place quickly in a pinch? At the very least it is a fun read for nerds. Brent is more of a boat artist then anything from what I understand, he just knows how it should be put together and goes to work for the way he does it. I'm just a dull trades men, but even I can appreciate the potential for a fantastic pleasure boat.

    6) What method of construction does safe boat use to build their vessels?

    Truthfully, I am more interested in building scale models to test, learn about boat fabrication techniques, and stick to what I know, which is grp. I just find steel an extremely versatile material and would like to gain more hands on practice applying it to the marine atmosphere. I have a lot of practical experience with things such as industrial rigging, agricultural rigging and fabrication, as well as heavy equipment repair knowledge. Right now I am trying to figure out what translates to boats, as I would prefer to morph into that realm professionally at some point. There also seems to be a wide chasm between what folks that use metals and rigging for work and yachties believe to be true. For instance, I hate stainless wire, pins, and most hardware. I have broken more stainless than galv in my working career due to the fact you can tell before galv fails from rust or stretching, and stainless just explodes. Also it is damn hard to find true 316 steel anything, and most the American crap I see is saddening. Galv also is far more fatigue resistant than stainless, and remains stronger longer. It seems boat riggers have a real hard time calling people back to provide inspections, quotes for materials, and even full re-rigs. Why put up with this when you can deal with a professional supply company that would love to answer all of your application issues, or even ask their engineering department and get back to you, all for way less cost. I am sort of getting sick of getting gouged for substandard service in the marine world, or just not getting replies. I understand some things are application specific, some aesthetic, and some just plain hype and marketing. I get it if it’s for style, or even because you are a racer, but a cruiser in a tub has different needs.
  3. Milehog
    Joined: Aug 2006
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    Location: NW

    Milehog Clever Quip

    An opinion from someone in the know.

    Tom Macnaughton, an engineer who set up the Canadian yacht design school has been warning people about Brent for decades. He has a succinct article on Brent's method that was posted on BD net years ago, I'll copy it here :

    " Periodically someone will just decide that the transverse framing is not necessary. They always come up with great sounding verbal rationalizations but have never actually done the math.
    The amount of weight you can save by tailoring construction to save the absolute maximum in weight, including custom spacing the transverse frames and other transverse members is so minimal and the mathematics necessary to properly predict where you can reduce transverse framing is so complex that I am certain that no one advocating the elimination of transverse framing has actually done the math.

    They are just building cheap, weaker boats.

    One North American advocate [Brent Swain] has written a book which he told me "proved" his case, yet on buying his book I found there was no real structural analysis in it and the one piece of math in the book which applied to reducing framing was wrong.

    There have been recent attempts to reinvent the construction method. Any reduction of the scantlings simply produce a boat less strong than the other methods. Naturally a rationale for this cannot be put in engineering terms. There it would evaporate.

    The overall rigidity of the boat is largely dependent upon the framing. This leads into another argument. This one says that you can eliminate the framing by increasing the thickness of the shell plating. While this would, in theory, and viewed in isolation be true. It does not really work out because stiffness usually comes from thin deep frame members with high section modulus for their weight. Thickening a thin relatively heavy plate to provide the lost strength from removing the frames is very inefficient. The net result is that if you eliminate framing you about double the weight of the hull shell.

    In an actual calculation comparing a normal hull framed both longitudinally and transversely with one that eliminated the framing the increase in weight of the metal structure of the vessel was 96%. Even disregarding the consequences for plate forming operations and welding operations of going to thicker plate, it should be easy to see that the large weight penalty is not acceptable because the performance of the boat will suffer terribly.
    Do we really believe that these people are making the shell plating as thick as necessary to gain back the strength lost by eliminating the framing, given this weight penalty? I think it highly unlikely in view of their claim that they can reduce costs. Therefore should a metal boat be promoted as “frameless” you can essentially say that something is wrong.

    A North American advocate [Brent Swain] has written a book which in one place compares the stiffness increase obtainable by using a thicker plate versus a thinner using an erroneous prediction of the relationship of thickness to stiffness. Presumably his entire system advocating reduced framing is justified by basing it on this erroneous calculation. There appears to be another interesting reason for this intense desire to justify reduced framing. We have noticed that all the structural members whose removal is advocated are the ones whose shapes are difficult to predict if you do not understand how to design the vessel with developed surfaces and produce patterns and plate expansions graphically such that every piece of the boat can be precut and can be set up and welded into a predictable shape.

    Instead of this fully predictive system these boats seem to start out as scale hull plate patterns created by trial and error by cutting shapes and “folding” them until a shape is derived which looks good. Then the full sized patterns for the plates are scaled up for various sized vessels. However this trial and error system leaves no way to predict the shapes of transverse frames, watertight bulkheads, floor timbers that follow the shape of the hull and keel, etc. Interestingly enough it is these same members whose shape cannot be predicted using these methods that suddenly are declared “unnecessary”. At best this seems an exercise in self-delusion.
    One final argument made for “reduced framing” is that if boats are composed of curved surfaces and that curved surfaces are stiffer and therefore don’t need framing. Let’s get real, even to figure the deflection on a simple curved beam of constant radius gets you into calculus. When you get into anything as complex as a boat hull with varying curvature in all directions, not to mention chines, deck edges, varying loads from ballast keels, large engines or rigs, the math pretty much goes off the charts. I just simply don’t believe that the folks I’ve seen advocating this as a reason to reduce framing have done these calculations.
    Even with today’s computers and some pretty fancy and expensive software achieving any significant weight savings given the normal complexities of hull shape is quite unlikely even without considering some of the other factors which tend to make it difficult to save weight in real world hulls. Among these are the fact that without frames to stiffen the structures all the stress simply runs to stress concentration points where the hull may be reversing direction of curvature, be flat for hydrodynamic reasons, have some sort of chine or other corner around which the stress will not carry without some support.
    Given all this the prediction of stress levels to sufficient accuracy in any given area to allow the reduction of scantlings on the basic of curvature becomes unrewarding and in practice is never done. My experience is that the people asserting that they can make such scantlings reductions, although speaking with great confidence and often with much disparagement of those who question them have not in fact done the analysis necessary to develop rational scantlings and are in fact just deciding to believe what they want to believe. One common characteristic of these promotions seems to be little or no space devoted to any real structural analysis of the relationships between methods. There seems to be a lot of space devoted to circular arguments saying that no proof is needed because only very stupid people living in the past could possibly not see the superiority of this new method. The evidence that these people are stupid is that they ask for the proof! These are “religious” arguments in that we are asked to “have faith” and those who doubt are castigated as lacking in the vision of the “true believer”. You will find us always on the side of “doubt” rather than faith.
    We are always worried that we have made a mistake, have failed to see a possible failure mode, are using a model that is not as predictive as it might be possible to construct, etc. The “true believer” is unencumbered by doubt and therefore need never check for mistakes, worry about failure of imagination, etc.
    We don’t buy into this and you shouldn’t either. In conclusion, do not be distracted from the lessons of real structural analysis by the promotional materials of these companies.

    This is simply another repetition of the mistakes that builders have made over and over. I would suggest remembering an old principle of design: If structural analysis says a boat is strong enough it may be wrong, but if structural analysis says a boat isn’t strong enough it is probably correct. "

    Tom MacNaughton YDS

  4. ImaginaryNumber
    Joined: May 2009
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    ImaginaryNumber Imaginary Member

    If you are still looking send me your email by PM or email, and I will send you what I have.
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