Fer-A-Lite

You really don’t understand what you’re talking about. Just say so, it is ok, no one will bite. Unless of course you continue with this charade of maintaining an engineering background and subverting opine as fact.

If the shell, or hull, as we call them in the nautical world, is made from paper, compared to one made from polystyrene compared to one made from FC, compared to one made from glass, compared to one made from steel, compared to one made from titanium, which is one stronger? Same hull…same size….just different material. Which..???

If all these different materials are “the finished hull”, your statement, they have by some miraculous event gained strength, why…because you say it is a ‘shell’. But if one made from paper and another from titanium….which is stronger, well, your statement says they are the same, simply because the material is a now in the shape of a ‘shell’

You really haven’t a clue about materials and structural design.

I don’t think you even understand what a composite is!

 

Since I am simply stating the same thing that the various previously mentioned designers stated regarding their own designs, albeit in FC not FAL.....

So are you saying that they are all wrong?

 

Ad Hoc,

No one said anything about the hull being the same dimensions. In fact, I have never seen a ferro design that had the same hull thickness as steel, or frp, and most certainly not wood.

Here, let me make it simple for you.

1 " finished thickness

30% steel 70% FAL would be much weaker than 65% steel 35% FAL, but it would still be tougher than portland in the same percentages.

So you saying a FC hull having x at x means nothing unless you specify the steel content, hence the armature as a percentage, which once again from everything that is popular common knowledge states that the armature plays a much more significant role in the development of the overall structure than the plastering material in a ferro type construction.

 

Ad hoc-- i think we are stating the same things in different wording...my point was simply that the frames on FC and even steel boats are just to provide a shape to form the shell. that the inherent strength comes-as you mentioned- from the thickness and modulus of elasticity. i used youngs modulus for my 30 "Ironwood" steel design...i got the equation from "how to design a boat"...i forget the authors name...
I agree with Darr and with no disrespect to you or anyone with an NA background- the truth is that many people who designed and built boats pointed out in their writings- that the "shell" provides the strength. At first for me that ran counterintuitive since framing members are quite strong..but after i understood the concept of thickness and weight/strength ratio's i understand it better... just sayin'

 

Thanks but please don't go to a lot of trouble to satisfy my curiosity alone. There weren't many of the TAMARACK design built and if this is a DOXY variant, even less, and the name is distinctive enough to make me wonder.

The wire frame photo does look like a Colvin hull; that full length shoal keel is definitely right, I've built one on my boat. I'm not familiar with the Brewer designs so can't say if he had something visually similar.

PDW

 

No. You're simply not understanding what you've read. With respect to steel hulls, the framing effectively increases the plate thickness by adding support to the skin.

It's really easy to see the effect of this. Take a 1m length of 5mm x 100mm flat bar. Lay it flat supported on its ends and put a weight in the middle of it sufficient to make it bend but not past its elastic limit (ie, it doesn't permanently bend). Record the deflection for that weight.

Now weld a bit of 6mm x 25mm flat bar down the centre forming a T. Put the same weight on it and measure the deflection.

Frames & longitudinals stiffen the hull skin and thereby add to the force needed to resist deflection.

Tom Colvin did indeed say that you could build a frameless hull but he also added the caveat that the plate thickness had to increase substantially in order to achieve the same strength/resistance to deformation. We have had a couple of long and quite acrimonious threads on framing and frameless designs. This thread - so far - is quite civilised in comparison.

There's no free lunch.

PDW

 

No, I actually want to thank you. I would not have caught the possible connection.

Anytime I can work a known boat back to its builder its great.

 

All new boatbuilding methods pass through three stages.
First, it is expensive.
Second, it is slow.
Third, it is accepted as being self-evident
lol

 

I think you're confusing 2 terms and this may be part of the problems.

The armature is the wire basket without any filler added, by my understanding.

The shell is the finished hull.

You can't use the 2 interchangeably. One could build an armature and plaster it with either FC or FAL. The strength of the armature would be the same in both cases. If plastered to the same thickness, the strength of the resulting composite shell would differ. FAL is weaker so you use a thicker coat, fine. Aluminium is weaker than steel so you use thicker plates, same difference. It really doesn't matter if it's a composite or a single type of material. The problem you have with this is, you don't know what the strength of that composite actually is because you won't do any tests on it.

Platt doesn't know either, he did a simple bend test which proves pretty much nothing as it doesn't tell you how much reinforcing at what orientation was in that single bend test sample that he does show. That is total crap, honestly. Without knowing the wire thickness, orientation and number of layers you can't draw any conclusion at all from it. I know you get all defensive but stop and THINK about it. If I used high tensile 6mm heat-treated wire longitudinally and covered it with paper maiche I'd get a sample with a much greater resistance to bending than I would if I used that same 6mm wire running transversely. For a test to be meaningful, you have to control your variables. Platt didn't and nor will you.

I did read the bit in Platt's document re using paper to finish the hull because the FAL was so sticky that it couldn't be effectively trowelled smooth. Now in 2010 you you think anyone is going to consider that this is a good idea? Are you recommending doing this to your customers? Your comment re the better job you do fairing, the less you have to fill is self-evident. You agree that FAL needs to be top-coated with epoxy to slow water ingress. Combine the 2 - paper to help smooth the surface and an epoxy barrier coat - and how far away are we from my comment about a f/g (or Dynel etc) skin in epoxy?

Platt on Page 20 says that it's recommended to apply a f/g skin over the wires before plastering. That's more time, materials and effort. I can't see how you can effectively embed the armature in the FAL by doing this either, you end up with a FAL bond to the f/g bonded to the steel armature. Maybe this is better, maybe not, maybe it's an option people don't do, it's in the PDF.

One thing that hasn't come up as yet. Just how many boat hulls have you personally built or personally supervised being built, and in what materials?

If you want to make claims against my professional liability insurance, good luck finding a lawyer in Australia that'd take the case. I'm not a naval architect nor a marine engineer, I'm a retired scientist and software designer who has had a lifelong involvement/interest in marine stuff. I'm happy to have all my postings here on public record and I'm happy to defend them. Ball's in your court.

PDW

 

For starters you are obviously deluded at 50% of 1 inch by volume as the steel content.

Lets for the sake of illustration Say you had 25% by volume in that 1 inch shell:



So the poor sod who's bought your prolific and very questionable sales talk has now gone and purchased the equivalent mass of steel to plate the vessel in 6mm plate right from the start And the steel is in a much more expensive form.

They now apply that steel in a way that ensures its considerably weaker in every respect than using steel plate, and have to fork out for an additional massive amount of expensive and additionally heavy coating to fix the holes so it floats:!:

All this takes a crippling length of time to build and the result is a relatively worthless hull.

Note the goo could be applied to the steel plate, you could even build the boat out of 6mm steel plate and then drill big holes all over in so the goo could stick better. But that of course would be stupid.... wouldn't it.

 

Promoting a new material, and then hiding behind this argument is morally dishonest.
You try to use semantic to get out of the corner you put yourself.
You can't do that.
With this argument, your whole new product is not worth more than a snake oil bottle.
At least defend your product, don't bail out when the questions start to be difficult.
Daniel

 

That is the whole part of this that is confusing, one says there is no data there to determine x. Someone else says based on the data it is weaker than Portland.

Most professionals I have dealt with over the years would not be making comments based on the material without analyzing the data and the good ones insist on running tests themselves.

Since you and the others state that there is no good data, how can you make a professional statement as to its strength or suitability.

Yet once again, without any first hand knowledge or hard data, judgements are being passed.

This may in fact be be lashing out by some professionals for the audacity of a common person to try to resurrect FC.

As a consultant in the technology arena, I do not make statements that I cannot back up to clients, or in the event of a dispute with a vendor or manufacturer that I cannot back up. I call it making sure my back yard is clean before I call zoning.

So in reality, the proper response from any professional on this site should be that without testing and analyzing the results a proper judgement as to its strength or suitability cannot be made.

Which is why I made a number of samples available at no charge to professionals who want to make a professional judgement on it. Some took me up on it, some did not. Hopefully they will share their experience at some point.

But I guess that is not as fun and entertaining as material assassination without the facts.

I did not come asking anyone for their blessing on the material, but once again, as the manufacturer I will take anyone to task who insists on damaging the reputation of the material without having first hand experience with it.

Simple things like

A professional says: I know of boats built like this that have problems.

The professional knows of one boat, but the way it is stated would lead the common person to assume that all boats built that way has problems because a professional said so.

That is a blatant mis-statement.

And this thread is full of them.



As I have stated before, give me proof and I will act accordingly in regards to the material.

 

I agree. It's concerning isn't it.

I'd still like the missing essential material properties, not the sales pitch about their incorrectly imagined superiority.

The product won't even produce as strong and rigid a hull as standard ferro cement designs built to the same specs, and would need a lot more bulkheading or web framing to keep the hull girder in place.

 

Mike,

I have to admit that I have an unfair advantage over you and the rest of the folks on this thread. I currently own both an FC and a FAL boat.

The FAL boat is much stiffer than the FC. Even though the FC has truss frames at the major stations, and a thicker hull, the FAL boat does not have truss frames and it is still the stiffer boat.

The FC boat was holed when it sat down on a piling during a storm (before I owned it.)

The FAL boat destroyed a good portion of a seawall before wearing thru a small opening. (sadly while I owned it.)

So I guess you guys better go back to the sliderules on that assumption.

 

No, you are wrong. Because you are taking statements from books or others sources, and taking them out of context to support your argument without knowing if the statement is even applicable to you.. Your failure to grasp what these “others” are saying is not a justification for your product. Just shows you are ignorant on structural design and theory, that’s all.

This is a classic case in point. You simply fail to comprehends a basic structural question, if I make a box, any size you want could be 1” or 1km, if said box is made out of paper, is this as strong or have the same strength (as you like) as say one made from steel?

To compare two materials, any 2 materials you like, they must be subjected to the same “test” or “theory”. If you do not do this you have no basis for comparison and all data obtained is meaningless.

Here is a very simple example in an attempt to show you your error in understanding.

If I take a sheet of A4 paper, fold it once, twice three times…..keep going to fold it until I can fold it no more. Then try and bend it…..not easy at all.

Now take steel 1mm thick, and span this 1mm thick steel over say from your house to your neighbours house across the street. Try and bend it….woaahhhh…easy!

Your conclusion is that paper has more strength than steel.

He’s confused about everything because he is not using correct engineering definitions. He is making up his own definitions and using “nice sounding words” to support his incorrect and erroneous definition.

Taking PDW's example further:

If you take that very same FB, now rotate it 90 degrees, ie not laying flat but vertically like an “|” then you suddenly can’t bend it so easily….but how, same material, same section same load applied…how is this possible???

Exactly that, there is no data, ergo how can YOU say it is so wonderful, since you cannot provide proper reliable independent verifiable data.

All the “evidence” you have provided is lots and lots of loose woolly words…no facts.