A Question About Planking

Yes, like you said earlier on these forums, true friends forever. -

 

Angélique, ___, do you think this discussion interests anyone? Let's be sensible,___, and let's end this nonsense.

P.S. I have deleted words that are not correct in conversations of this type.

 

Many of (directed at the original poster) us here have been participating for some time and relationships develop over the years, in some cases decades. This is a natural progression of friendship and respect we've learned about each other, across this time period.

About "changes a lot", I'd suggest the wholesale removal of all the athwart framing system, when comparing a traditional lapstrake's typical arrangement to a glued lapstrake, significant enough to want the scantlings to have been "changed a lot", wouldn't you TANSL?

 

Post # 32 ↓

Do as you say, and you won't be a liar . .

I suggested far much earlier to you, in an bit indirect way, to take your nonsense to a more appropriate place . . .

Post # 14 ↓

Post # 21 ↓

Edit = corrected a post №.​

 

I respect a lot and I consider myself a friend in the distance of many members of this forum, with some of whom I have had important discussions. That has helped me to know their worth as people and as professionals.

PAR,my friend, I would raise here two, let's say, new points of view or approaches to the discussion:
- How are the scantlings calculated, what procedure is followed to calculate them, in each case ?. I can have my ideas about it but I do not know how you do it. When I know your method, perhaps, I can clearly deduce why they change a lot from one case to another.
- In my opinion, many boats could be made without frames (I'm thinking of kayaks, dinghies or similar). The frames are necessary when we want to give the hull a certain shape, far from what the normal flexing of a wooden board can achieve. So, if the frames are necessary to get that shape, to say that one method or another allows to reduce the frames, or to eliminate them, does not seem to fit the reality. But, if the frames are necessary and we can not eliminate them by what has been said, let's use them as resistant elements that will reduce the thickness of the boards of the shell. In my opinion, the opposite reasoning (the tables allow to reduce or eliminate the frames) is not correct.

 

There are centuries of data to show that lapstrake can be lighter than carvel in smaller hulls. We are obviously not referring to ships. Frames are not necessary to give the hull a certain shape. They are structural members. In many construction methods, they are installed inside the finished planking. For example, in lapstrake. As to your question on how the scantlings are calculated, that depends on the method used. Most traditional designs follow customary rules of thumb that have historically worked well. More modern methods use displacement based calculations. With the advent of computers, many calculate scantlings through FEA or similar programs.

 

Thanks a lot, Gonzo.
Question, "how do you calculate this"; answer, "this is calculated as best as possible"
FEA is not a program, is a method of analysis.

 

TANSL, don't you think your pre-last post, and also your last above post, goes beyond the initial objective of the OP ?

When want to learn about boat design, why not start a thread of your own ?

 

Post #37 ↓

Honey, your deliberately and also unjustly twisted summary here is unfairly ridiculing Gonzo's knowledgeable and comprehensive response . .

So my dear TANSL, since you've not stopped your nonsense, please check the first line in my pre previous post (#34) for what that makes you now . . .

Post #32 ↓

Post #34 ↓

Edit = corrected a post №.​

 

Post #29 ↓

Just tracked down what post you meant, yes he nailed it there, fortunately you got this one . .
Post #26 ↓

 

A computer program (aka software) is a collection of instructions that performs a specific task on a computer, such as executing FEA analysis.

You seem to have a serious problem there buddy, such as trying to get other people down with twists and turns and inappropriate arguments . .

 

Yes you nailed it there. This "as best as possible" is usually by using a prediction model in the form of different scantling rules. They are based of a collection of empircal data and the interpretation is highly biased. Different scantling rules produce different results because they reflect different atitudes towards safety factors and are usually adapted to local conditions. Basicly the same thing as modern ISO rules for boat construction. A subjective opinion on how it should be, only that this opinion is law in some places.

If you want to go back to first principles engineering that is possible. For carveel and other mechanicaly fastened construction systems it is complicated and time consuming. I am not aware of any modern computer aided tools to do this. Probably because there is no market for it, the people still designing and building like that either voluntarily follow one of the rules, are required to do so, or simply build by local tradition ignoring established rules. The primary reason to go first principles would be racing, but how many no glue wooden racing boats were launched since modern powerfull computers became common?

If you do go there please keep in mind following basic things:
Wood has no standard fixed properties you woud have to test each batch. The properties given in reference works are averages and changed over time and with location.
Mechanical fasteners in boats are regarded as only working in shear. Wood moves and it's not possible to assure a tight enough joint for them to work in tension. Because of this movement planking is regarded as a consumable, to be replaced after a specific time period. Wood is regarded as being completly anisotropic, so fiber orientation is critical. Carveel construction is based on the asumption that the framing carries all the loads. Every fastener hole weakens the wood, so the wood must be sized so that it retains sufficient strenght in the presence of fasteners.

 

@Rumars, this is the second time I have to say that your explanations shed some light on the obscurity that surrounds me about this subject.
By the way, I am glad you agree with me that wood is an anisotropic material, it is not cuasi-isotropic, as some think.
I am not an expert in designing "traditional" wooden boats. I know ISO 12215 well and, according to it, I have designed some wooden boats (very few). This method does not explain any method for clinker construction but it does for wood in strips (supposed to be glued) and for plywood. So I do not know abso- lutely nothing more about it. This standard, and I suppose the Classification Societies, calculate the panels like that, like panels, with their four embedded edges and calculates them by the plate theory. Reinforcements, extrusions, etc. Calculates them as beams embedded in their ends, subjected to certain loads, in general, perpendicular to its longitudinal direction.
And so far my wisdom comes.
When I read that the building in clinker changes the scantlings a lot (see correction below), I have a light bulb. I am not old enough to learn or have time to learn many things but my curiosity has aroused because I did not see a reason to explain such a big change. That's why I started to ask. After answers that did not clarify anything (I am probably not able to understand what is explained to me in English) I thought that, perhaps, if I knew how these ships were calculated in the last century, I would be able to deduce the reasons for all that. That's why I asked the how.
The experts (I believe they are) in the construction of wooden ships have not gotten me out of my ignorance.
It is very likely that, as happened years ago, everything was done as it had always been done, without asking why. But I am sure that the most expert have some formulas to calculate, for example, the thicknesses of the sheets (or strips) of the liner. Those formulas (something like kitchen recipes) would not be the same for the clinker system as for the carvel system. If I knew them, perhaps, I could find out something. Let us not forget that many formulas of the bending moment (BM) used by the Classification Societies are, in the end, no more than BM = P * L ^ 2/12 or BM = P * L ^ 2/8, with Safety coefficients, accelerations, ... which vary from one CS to another.
That is the source of my insidious questions. I'll probably have to settle for knowing what I already know on this subject and nothing more. Not because of friends who have kindly tried to explain me but because of my inability to understand them.
Thanks once again

Correction according to Angélique's warning : instead of "When I read that the building in clinker" should have written "a glued seam".
(I feel a deep respect for PAR, and he knows, and at no time would I pretend "twisting or turn him off," whatever that means).

 

That is nowhere said for clinker on this thread, it said in post #2 already that scantlings change a lot when converting to a glued seam lapstrake, which is something different than clinker by definition, as all over the thread is said and explained many times.

It is also all over the thread said, and explained, that a traditional clinker build is a bit lighter then a similar boat build in traditional carvel.

Your problem to comprehend is just your twisting and turning of other peoples words for ill polemical reasons, as comprehensive explained above, and as a very small part of it in the quotes below. . . .

 

TANSL I do believe you are able to understand me better not because I say new things but because I am able to reformulate what the specialists said. I am not a trained naval architect and I am not able to provide detailed answers to your questions. But I can see you lack some common ground to understand some of the answers. Language is not the barrier here.

I believe you need to read a book about traditional boat building methods and the way they are calculated in order to be able to formulate the questions and understand the answers. Maybe someone more qualified than me can recommend one.

To continue with some laymans explaining (I am the layman, not you):
In some of the traditional no glue methods plate theory can not be applied for calculating the planking thickness because there is no plate (carveel), or the plate can only carry a limited amount of load because of the fasteners (lapstrake). Planking only resists hydrostatic loads and handling loads (abrasion from normal use, deflection from point loads, etc.). This is only the theory because in praxis other factors also govern scantlings and are often more important then calculated strength or stiffness, like the ability to hold caulking for planking (otherwise the boat sinks, important in small light boats with thin planking), sufficient material for fasteners (the moment people started using metal fasteners instead of trunnels scantlings became smaller and boats lighter), method of achieving curved sections (if a frame is buildt out of many straight sections it is bigger then a bent or grown to that shape one), sufficient thickness to allow for rabbets (the backbone could be smaller otherwise) and so on.
For all this reasons scantlings rules, either local traditional or "scientifically established" ones are a fast road to success in traditional boatbuilding. Outside of racing and military commisions nobody wants to pay for ground up engineering, and in some jurisdictions the old rules are still valid. As far as I know under ISO regulations such traditional methods are excepted (boats and copies of boats buildt by methods and materials before 1950) but where national authorites still verify and certify the builds (I know of at least one country in the EU that requires plan approval before build, as well as build suppervision) old national or international scantling rule are used to demonstrate compliance.