Realistic scantilings

Crag,

Noone is saying Lloyd's or ISO is the end-all to boatbuilding. But just because we need to move forward, to innovate, that doesn't mean we can dismiss it all. That we should abandon everything in them. That argument is like saying that just because science isn't always right, we should abandon science as a method and go back to the dark ages. In reality, Brent and people thinking like him (i.e. science and math is something evil, and we should all shun it), are the anti-copernicus. They are wanting people to trust unfounded claims, they are the church, they are the religion.

The thing is, if one wants to deviate from proven rules, one has to use logic and arguments. In other words: There better be a well-founded reason. One cannot simply dismiss them all, simply because one dislikes the rules. That is tossing all knowledge aside, all so you can make any more mistakes. Although, as I said earlier, even a blind man can hit the mark. But if so, I'd call that pure luck.

Now, would I want a boat build to Lloyd's standard? Well, not exactly. I'd prefer to go above and beyond many of the detailed rules. Some should be rethought and so on. But that doesn't mean I would completely abandon them. And you don't need to abandon prior knowledge completely to go forward (please don't give me more copernicus - it's definately not the same, since the church and religion as a whole isn't based on knowledge, and certainly not on logic, nor proven methods, proven rules of thumb).

Add (I also added a bit more to the above): I wholeheartedly concur with what Murielle is saying about this in post 74.

 

I think you may be overstating the amount of hard science in boat design. We are still struggling to explain and quantify a fraction of what happens in the dynamic environment. We spend much of our time reverse engineering what we can see to work. That is why when we have the opportunity to evaluate a body of evidence that would appear to be outside of established norms, we should grab the opportunity with both hands.

As an aside, it was the church's dismissal of Copurnicus' observed events as plain 'wrong' because they contradicted their 'established' explanations of the solar system, that was the parallel with this situation.

So if a way has been found to construct steel boats that are proving satisfactory in service, then they cannot be dismissed because they represent a sea change from established thinking. Mr Swain doesn't have to to explain why they work, or give any logical explanation or rationale, or relate them to any prior thought processes. To contribute meaningfully to the advance in our knowledge of steel boatbuilding, he has to simply state what he has done and give enough detail so that others can repeat and verify his claims. The explaining of why and the implications of such work can follow later. It's an entirely valid way of research working in any field including engineering. Not every advance is sequential or derivative.

 

I am not overstating anything. Just because it's not possible to explain everything doesn't mean it's okay to abandon what we do know. On the contrary: Scientific method means that one are building upon the proven methods and knowledge, yet try to disprove already proven theories, methods and knowledge. Yes, it sounds like a paradox, but it isn't - it's merely the way science work.

Nothing wrong with reverse engineering. On the contrary it's my point exactly: You're actually getting your theories to fit with the real, getting your math to fit with the real, putting it up against eachother in order to move forward. Again, it's the scientif method. You cannot deduct that because we are not able to understand everything, and we have to do calculations to make things fit (reverse engineering), that it's all fine and dandy abandoning every calculation, all the proven rules and so on.

Further, with Brent Swain's designs, you won't get the "opportunity to evaluate", because he apparently just flicked something together, guessed, and was done with it. At least that's how it appears, since he doesn't want to give any information, no analysis and on and on.

As I said earlier on, it's quite the reverse. Copernicus had data, had calculations and could thus scientifically prove that the earth was round, that the earth went around the sun, whereas the church couldn't.
The only comparison between Swain and Copernicus is that they both went "against the grain". But so does the guy who crosses the Atlantic in a (literal) bath tub. Going against the grain is not the same as proof, nor does it mean that one is automatically right. One has to do much more than that.

If you don't think so, we might as well abandon every professional in every field there is. Let's do away with brain surgeons and let amateurs do it with huge bread knifes on the kitchen table without washing hands. I mean, it's "going against the establishment", if I begin doing it, I must be the new Copernicus.
The thing is, even though modern brain surgery aren't flawless, without risk and so on, it's properly better to use the knowledge already acquired and come up with new methods, based on the old ones. Oh, and remembering washing hands _unless_ one can come up with something better. But doing something differently doesn't mean that is per definition better.

Noone is saying that. However, we only have Swain's claims that they are. Further, the mere notion that the people he sells these plans are in effect beta-testers that are out there testing the material. And with the sea, someone might get killed because of poor "design", even if most of the beta-testers don't, or not too often.

Yes he does. Especially when he claims his boats are better than everything else out there.

That he has to do as well.

Yes, let the buyers be testing them. You know what, I'm going to sell you something I flicked together out of cheap sheet metal, coppled with bronze. It has a huge cockpit and is topheavy. Oh, and did I mention I nixed the keel in the process? Let's let the whys and the implications of my "design" follow later.

No, it's not. But again(sigh!), it doesn't mean one should just ignore all of it. Even the basics.
It's a sad day when people will trust their life and the life of their families on the notion that "Science cannot prove everything, so let's ignore it completely. Let's ignore calculations, because if we're lucky, this boat will prove itself to be safe".

 

Surely we don't just have Mr Swains claim's about his boats? We must be able to see if they really exist, have really done these voyages and whether they have had any problems? Are his customers lining up to complain about his boats? Do they have website haranguing his designs? Are Trading Standards investigating him?

Whatever his methodology, it's entirely possible that he has happened apon something that works. We are not talking brain surgery here, we are talking steel small boat building, which is probably the most conservative branch of boat building. It's always appeared to me to be ripe for innovation.

Also don't bring stability and other issues into this - that's a whole different can of worms in small steel boats that is best left unopened. It's a distraction from the issue about whether it's possible to evolve of scantling regime that doesn't conform to established norms.

I would love to see an account of how grp boat building, or pioneering multihull design, would have evolved in your perfect world. My memory is that designers and buildings took huge leaps of faith and a willing public lined up to do the beta testing (at best).

 

And we're back to the strawman-argumentation.
I am saying that his claims about his boats being stronger and better than everything else out there is unfounded. That his claims (based on anecdotal evidence of slamming into a reef) about his boats being at least as seaworthy if not more than anything else out there is equally unfounded and that we only has his - the sellers - claims to rely on. If one is making these sort of claims, one better have done some research and the needed calculations. Boats sailing around is NOT a proof that his boats are all that. McDonald's, anyone?

Whether people line up to complain or not, doesn't really matter. People don't line up to complain about McDonald's burgers after they bought a burger there.

Oh, and need I mention that an abscence of evidence doesn't mean evidence of abscence.

Yes it is. It certainly is. Noone is saying it's not possible. On the contrary, we have all said it is. The thing is, though, we don't know. All we have is claims and the lack of complaints, which apparently means it must be a great design (you cannot deduct that).

I KNOW we're not talking about brain surgery! Sheesh! Go read about what I said about the Reductium ad Absurdum.

Of course it is. Innovation is good. But clamping something together like a blind man, completely abandoning everything, denying to provide proof of the thinking, strength and so on, all the while claiming the "new" method is much better than everything before, is not "innovation" - it's simply "taking a stab in the dark".Sheesh, I feel like we're starting all over on this thread. It seems like you're convinced that by continue to reiterate the already refuted claims of brent's it will somehow wear us down and if we give up, you guys must be right. There's a word for that strategy, but it escapes me at the moment.

Sure. But the thing is, it's a part of sailing a boat safely. Especially considering there's more to boat's safety and strength than anecdotes about how a boat slammed on a reef.

No it's not a distraction. See above and read the thread. We have said and explained why that is also part of the equation.

I am not talking about a "perfect world". Not in the least. Will you stop playing a Brent on me?

I sincerely hope to not having to reply any further of these "restatements" of what Brent has already said and which has been refuted. If I wanted to keep refuting his claims and the problems with his argumentation, I could just go back and restate my answers, elaborate on them and so on. I don't have the need to, quite frankly.

 

Here is the sort of construction which I made my comments on previously. Did not mean to offend.
Just the other side of the argument this looks awful. the eye begs for the line to carry on and it looks like it just had an operation ...... eye of the beholder I know.

Crag Cay

Did you read the full thread ? It seems that Brent has a very ad-hoc approach and the concern is that he hides the details because I think he is worried someone will simply show that he is wrong. He is quite mis-informed in structural engineering from my viewpoint as a civil engineering student.

How about some in-service measurements? where is the engineering follow up to assess suitability for service before selling another hopeful the same design. If there are serious concerns they need addressing, not hiding behind verses chapter and personal ego in repeated emotive sermons.

You notice that people with very over developed egos don't ever give any ground. Would you trust such a person to tell you if he discovered he was wrong ? Not saying he is just would you trust a consummate marketer with ego and attitude to tell you he’d possibly screwed up? Or would you expect him to quietly change his designs and keep quiet ?

As for engineering analysis. Forget the dynamics for a start and look simply at rated pressure heads. Apparently ABS that you mention has shaved it for racing boats. The latest is that it is not sufficient for racing boat decks and needs increasing. Surely this is the process that the rules are based on. This is why the rules work. Brent claims they produce overstrong hulls and that his weaker hulls are good enough for the job. But then shouldn’t he show some supporting analysis other than anecdotal? This is also an allowed approach by scantling societies it is called specific design. But you have to submit calculations and analysis OR adhere to the set rules. They are sensible enough in this approach.

 

LyndonJ
I cant argue on the engineering part because Im not an engineer, I'm just a welder but my 26 sure seems to be stiff with no flexing anywhere, even when I leaned the boat forward about 10% setting on the tip of keel and pouring in 1800 pounds of lead.
Like you mention eye of beholder, some like the looks some dont but I hope you dont think that is the only look you can give it. Some have cut the chine out and replaced with split pipe or rolled sheets and blended in the radius. There is a picture of a 40 footer in aluminum that did it and she looks good, Its in yahoo groups origamiboats. same with cabin top corners, if you dont like the square look do the split pipe corners, they look beutifull but a heck of a lot of extra work. Its up to you and your skill.
Tom

 

Crag & all



If you want to be innovative particulalry with metal boats then it would be a good idea to team up with (or run your designs past) an engineer, an experienced engineer will usually be aware of several unforseen issues.

Note that we are not damning his designs, they might even be compliant, particulalry his smaller baots. Impossible to say without some info that is not forthcoming. What has been mainly provided is diversionary argument to change the subject away from actual design. Shame really.

Many people Brent included misunderstand the science behind engineering design. We can predict very accurately just how an isotropic material will behave under load. The big problem is identifying the load not the reponse of the material. We design to a combination of pressure head, global strength and operational loads . The rules seem to have the pressure head about right for small boat design now also in smaller boats the main structural member is the hull skin suitably stiffened one way or another and so smaller boats are more forgiving for the designer.

A heavy or medium heavy 55 foot steel boat sans transveses or bulkheads is starting to get into more concerning territory, It is of a size that could easily absorb a bulkhead and some frames. It would be interesting to see the hull deflections in heavy weather. Then the shrouds and stays and mast get a real workout.

Engineers specific design 'all the time' for scantling society compliance. The rules do not stop any innovation and we can be as innovative as we want so long as we satisfy them that those loads are within the factor of safety that they require. It's our neck on the line if it fails. So i'll just make that FOS 5 rather than 2


Building engineering is mostly concerned with relatively static loads applied at their maximum values; wind loads, floor loads and support. This is always analysed in depth and is a very good example of applied structural engineering and how well it works when the loads are known. Innovation in architecture is continual and safe because of this approach.

I would argue that this is applicable to boat design too. Spectacular failures - yes at times because the leading edge performance composite designers have two problems firstly their orthotropic materials are hard to analyse (compared with isotropic metals) and secondly those darned loads are a lot higher than they often expect particulalry when they go faster.

 

Tom

I think what everyone is saying is that small steel boats like your 26 footer are very likely to be strong and stiff enough and compliant in all respects.
The limited shape is the tradeoff for easy building.

I guess the hillbilly comments are about the people who Brent markets at with his anti-science rhetoric, other people will build his designs for other reasons too.

What everyone seems to be concerned about is that you cant just scale a 26 footer to close to 60 feet and expect it to be stiff and sufficiently strong for the loads a big sea will subject it to without wracking bending and oil canning (or just exceeding the fatigue design limits).

Talking this over with the NA's and it is clear that larger (small) vessels should be able to cope with significantly greater pressure heads for the unforseen events that a true blue water cruisier can meet. Otherwise it should be limited to coastal cruising.

Looking at a spreadsheets of scantling rules from ABS DNV USL and GL it is interesting that GL seems a lot lighter than ABS and DNV for yachts and that perhaps GL have given more serious consideration to smaller steel boats already as Crag Cay was suggesting was required. They also give guidenxe for longitudinally framed boats which is what Brent has been doing.

Apparently the workboat standards of all rules that came first are a lot heavier than leisure boats and have evolved to cope with higher loads all around.

 

Mike

The last harbour I was in(Nanaimo BC) had ten of my designs in,including one circumnavigator. The town I'm in now has six including one Pacific circumnavigator. There is your proof. Any one on any of these boats can tell you where the rest are. I have yet to se a McNaughton design anywhere.
Have you read any of the books on cruises in my designs that I've recommended?
You say they don't exist.You are a liar.
Is this the same Mike who stabbed Alex Chritie in the back, after all he has done for metal boatbuilders, by claiming a boat with all the steelwork finished was only worth the price of scrap metal?
Yes, everyone, including Lloyds has some good ideas and some bad ones.
Brent

 

Ha ha, no. You claiming as much is not anywhere near to proving anything. It's _still_ just an unfounded claims. So there, prove it.

Well, you continuing to to make that claim doesn't in any way, form or fashion make your claims valid arguments.

What's your point? As have been pointed out on several occassions, just because some have succeeded, doesn't mean your designs are inherently safe, and certianly not that they are better than anything else out there as you have claimed. Or put another way, as have been done on likewise numerous occasions: Anecdotal evidence is just that: Anecdotes. And you cannot simply extrapolate from anecdotes.

Strawman. Noone is saying that _none_ of your boats have been build.

Ad homimen.

Ah, how swell of you. Now, how about you put up or shut up? Up until now, you have done nothing to validate your arguments, nor have you provided proof of any of your claims. The closest thing to something real is you "backing up" your claims with further claims, using strawmen, ad hominems ad naseum, stirring it in that big pot of stink you consider "proving your point".

 

It would help if you addressed comments to the recipient.

If you are reffering to me as 'The Mike' the answer is NO.
I am intrigued though, was this a large structurally defficient vesseel?

Why do you always do these sideways leaps into the stinking swamp when the discussion gets firm and technical ? I also think you would find Germansche Lloyds ( Not Lloyds ...different organisation) small vessel scantling guide very illuminating too. Read it it's free on their website.
Arvy who started this thread is probably worth you contacting for some offline advice, he has probably got to grips with it by now.

ABS also clearly and simply identifies the loads that have been identified as the desirable safe design criteria (from experience). So here's two simple questions that any prospective client should ask you:

What is your design criteria for the foreward lower pressure head on a 57 foot vessel ? What analysis have you done to ensure that this load can be resisted without any transverse support?

Very simple questions, simple enough calculations that should be adressed for every ocean going vessel.

Then there's other very basic calculations like COG, GM, Vanishing angle, roll period, dellenbaugh angle that will all tell a prospective a lot about the boat thay are considering. Do you even furnish that information ? In Europe they have found a need for people to be informed so that they are not taken in by marketing hype and can judge a vessel in comparison to other vessels on the 'numbers'. Every client I have these days wants a rollover stab curve and knows what to look for on them. Sailors are becoming better educated and it seems to me that a designer who spurns education so vocally is not shooting himself in the foot but blowing one of his legs off.

 

Not to mention the mast loads imposed on the chainplates when the mast goes into compression, inertias etc. Lets not spook this guy with numbers Mike

And before I (we) have to listen to another rant from Brent, consider this whereas diplomacy, some sensible advice, questions and challenges are rudely ignored or answered.

"Never argue with a fool, a person that happens to walk past, may not know the difference between you - and the fool will beat you everytime with experience"

 

Mike
There are several pages in my book pointing out the geometric principles involved in the structural characteristics of origami hulls. I guess I was talking over the heads of some, like McNaughton.. Sorry I am unable to talk down to their level , but kindergarten was along time ago.
When you get off the ferry in Nanaimo start walking south. Behind Muddy waters pub, you'll find two of my designs, Viski and a 31 footer. Further down at Newcastle marina , you'll find a couple more , Serafina and Puna. At the yacht club you'll find another 36 footer. In the harbour there were 4 anchored out the last time I was there. Some may have gone cruising. Being debt free, they are free to do that.
In a backyard at the top of the hill on old Victoria Rd you'll find another. In Ladysmith at the maritime society you'll find another , if he hasn't gone north for the summer.
Do you want to put your money where your mouth is and bet $5,000 that no boats of my design were ever built? Or ever circumnavigated? You don't have the huevos. By failing to take the bet, you admit that you are a liar. Your credibilty has dropped to zero.
The decks , cockpit and cabin on my boats are all 1/8th inch plate , with the stiffeners installed and welded before installing the panels in the hull , as on any other steel boat.
Loads on chainplates are far below what the hull can take( or windward shrouds for that matter). You can put a hydraulic jack at that pint and pump it as far as it wil go without deforming the hull in any mearureable way. I make my chainplates, out of 1/2 inch plate. The weight is negligible and there is aboslutely no disadvantage in going for a huge overkill. Ditto for rudder fittings.
Why don't you make a sheet metal model of an origami hull and see for yourself how much stiffness you get from shape. That will answer a lot of your otherwise naive questions. It only becomes self evident when you actually try to twist a sheet metal hull. The irrelevance of transverse frames also becomes self evident at that point. Try it before making anymore naive coments here. I've done several dozen of them.
Brent

 

While a second opinion is always helpful I suspect that the average person would really be put off by some of the bull headiness demonstrated by the engineering crowd in this thread. Especially if the case was one of implementing new design methodologies.

As a third party late to this thread the above clearly goes both ways. For example the issue of transverse structures and the relationship to hull penetrations. I've seen Brent dismissed several times in this thread with respect to that one issue but as far as I can see he is absolutely correct.

Considering the number of probably engineered ships that have in the last few years sank because of hull penetrations there is reasonable reason to believe that modern ship engineering leaves a lot to be desired. Here I'm talking about the larger ships that went down in the arctic and med.

Exactly. So why not analyze the boats correctly to see if there are any real problems? In any event I'm with Brent at least in the idea that the strength of the hull is an important factor in a boat ability to survive certain sorts of unplanned exceptions.

In any event back to modern engineering, how much effort is put into the hulls ability to survive outside exceptions. That is collision with objects, rocks or other ships. Further more which would you rather have, a hull supported with a rigid back bone that is easy to penetrate or one without that has a higher tendency to deform?

The fact is that a lot of very small boats are nothing more than the hull structurally. An Origami only extends the boat in size.

Only in the sense of what you know of and have been trained to? If such a boat was analyzed from the ground up would you feel better? Something that would likely take an engineer willing and able to throw off his preconceived notions and training.

Yes it would. Again though there have apparently been several engineers posting in this thread that have offered up nothing with respect to sound engineering investigations. Complaining about something because you don't do it that way isn't very constructive. Instead show us some sound engineering studies that support you view as an engineer. See that is what I'm hearing in this thread, to paraphrase: Origami can't be any good because we don't do it that way. No there hasn't been anyone person saying so but the tone that comes through is just that. A well trained engineer could easily prove either himself wrong or Brent wrong through a bit of computer time.

But the engineers contradict that in this thread. The overall tone is that anything that moves away from structures with conventionally spaced traverses is a no no.

Which frankly hardly applies to boats/ships. They are continuously exposed to dynamic loads, wear and tear, collision and threatening things like hull penetrations due to any number of causes.

Notably Brent is saying he has not had any of those spectacular failures. Now I don't have the info to say if that is true or not, what I'm saying is that the people (the N/A's) who should be able to offer up a sound evaluation of the designs aren't. By sound evaluation I mean full spectrum of modern engineering techniques including computational methods. Frankly Lloyds has nothing to do with it, as Crag Cay pointed out, not all of what is in Lloyds is based on modern principles.

The other rather scary bit in this thread is the idea that the only worthwhile vessels afloat are the ones designed by engineers. Frankly that flies in the face of history where the vast majority of the ships afloat never had the good fortune of structural analysis. Even more so, as you point, many that have had the effort fell apart anyways.

One more thing before I go on. You seem to be obsessed with your isotropic metals and sound engineering. That is all well and good but I live right next to Lake Ontario one of the great lakes and there are still occasions of large commercial vessels going down. Mind you this isn't a massive storm in the Pacific or Atlantic either. One could make a very good argument that the success of Brents designs have more to do with the owner - builder - user mentality of building the vessel to keep ones *** intact.

Dave