Transverse frame calculation

So you ignored buckling.. Lord Lindsay of steel

 

You mean the claim that you can easily buckle a 3/16th plate beer can? By hand?
If T- boning a steel barge at 8 knots won't buckle a hull, what will? Do you have your
"Sky falling" insurance yet?

 

I need only close the cap in the noon and have a collapsed can in the evening so no hand needed, anyway if the can is big enough.. But as others have stated, why you can't do with frames or bulkheads if that's more convenient?? I'd rather have a belt and suspenders than an insurance against dropping me pants..

 

http://www.youtube.com/watch?v=ZGhAeG13MTI&feature=related
http://www.youtube.com/watch?v=Uy-SN5j1ogk&feature=related
http://www.youtube.com/watch?v=2WJVHtF8GwI&feature=related

 

Sure, but that would only help if your boat was a sphere, or at least a geodesic structure (paraboloid, hyperboloid, etc).

But even if it were.... you really only gain geometric strength at the seams by creating effective lancet arch (assuming all curves are of positive curvature with respect to the cross-section [negative curvature or inward pointing seams would result in catastrophic failure]), if the "plates" are ideally shaped they will be effectively funicular/alysoidal arches. This strength is very directional and tries to forces the seams apart, in a welded structure, this is your weakest link not only are welds weaker, but considerably less ductile and more brittle than the parent material. So even in the most idyllic case... The lack of bulkheads prevent the structure from maintaining these "perfect" structures when they experience torsion, face deflection, etc. The only possible outcome when this thing fails is for it to catastrophically unzipper or catastrophically implode/collapse, and it doesn't need to have some massive "all at once" impact, little wiggles and torsions here and there fatigue those welds, and unzipper when you least expect it.

There are quite a few cases of boats (granted they were bigger), that bursted and unzippered at the welds just do to the temperature dropping over night in a heat soaked metal.

 

Brent... this is a bit ridiculous. It may be true that if I had disconnected transverse frames then I could flop it any which way. But imagine you have one of those toy floppy wooden snakes?

Due to the geometry it cant twist at all, because the frames reference each other. Each frame is close enough to the following frame that it has markedly less twist than if it was frameless altogether.

Ok, now that we got that... think of the same snake...

Now put a skin on him, and bond the skin to the frames? What do you have now?

A baseball bat.


Further...

The only reason a deck provides any significant protection from bending longitudinally or torquing is it prevents the hull skin from buckling prematurely. Or, exactly what frames do much, much, much more efficiently.

Just think about what you said for a second.... its like you are building a house, and you opt not to put any diagonal 2x4s in the house. And you say.... don't worry the foundation is made of concrete!

Moreover if you just had longitudinal frames.... there is nothing but the skin to hold them together/apart and in the direction they need to be providing the most support they basically don't provide anything.

 

bearflag, now you are getting the idea that Brent thinks bending and buckling are basically the same and that most if not all loads are in compression throughout the hull.

 

I have to give Brent some credit though...

He is right about one thing, that he is taking advantages of the vast mechanical properties of steel. No doubt if the material was lesser, we wouldn't even be having this conversation.

With that said, I'm not sure why he is so resilient to the idea that unless the cross section of the steel is massive ( "MASSIVE" ) that internal framing provides no benefit.

That is not to say that the internal framing need span the cross-section. As I mentioned before there are geometrical options available, as additionally there are skin on frame structures, and sandwich structures (think like a honeycomb with skins).

 

No, not like Herbulot. I use to know the man, he was open, extremely curteous, always listening to ideas, a brillant naval architect, a perfect sense of engineering, and eleguance in simplicity, and never ever dismissed a discussion to try to be right.
So please don't insult the great man.
Brent is far from that league, and I doubt he will be there.
As for your last sentence, its is quite chilidish. I will not tell you why.
And contrary to your beleif, a boat or ship can be design perfectly. And it include several hundred worker to do it, not one person. The nobody is perfect is a little short of reality check.
Daniel

 

That last one is worth looking at . Similar to the collapse of Brent's proposed 60 foot unframed boat diving into a wave one dark and stormy night. But wait it's curved so every bit is supported its neighbor and the steel would need to rip in tension to fail ..........................

Even if you framed it longitudinally it would just straighten out the collapse creases, not stop it collapsing. It's a misunderstanding of failure modes that has sunk Brent.

I was sent another email, apparently one of Brents 36' boats as designed by Brent hit a rock and broke welds and the hull was breached. Brent knows about that apparently. What's the story there Brent ?

Also this fixation on the anecdotal T boning of a barge, doesn't illustrate anything. How did it pan out? did the boat ride up, did the barge side bend, was it well fendered? What size was this barge. Presumable it was low in the water and small and taken on the stem. Given the inertia, mass and steel thicknesses it didn't bounce off and the energy had to go somewhere.
It's easy to use anecdotal tales as arguments. But lets substitute a concrete harbor wall for the barge and try again at 7 knots as you claimed, I'll put several thousand dollars on significant bow damage and some severe deck and topside buckling.

Here's a simple wager, take one of your 36 footers and ram into a wall at 7 knots, If I'm right I don't have to pay for the repairs....If I'm wrong I do..........ok

 

Ok, so are there any rules of thumb for building a boat to resist crushing pressure? I mean, its not a submarine, but part of it could be for a few seconds especially in high seas.

The plan I have in mind is a high L/D aspect performance, multihull, possibly semi displacement or wave piercing, one could imagine a pitching ocean where the boat could be pitchpoling into the wave and achieve wave penetration deeper than the vertical buoyancy would ever allow. With the weight of water being as heavy as that is, the forces could be gigantic. Even if it is "only" a few feet of water depth for a few seconds. It would be better than not to have my boat not look like the railroad car that both of us linked.

 

That question is answered here:
http://www.boatdesign.net/forums/multihulls/proa-questions-33138-2.html#post372968

But you are digressing. If you wish to learn more about boats, may i suggest you start your own thread with your own questions.

This thread is about the misconceptions regarding frame versus frameless boats. As yet every "cliam" has been countered and proven to be baseless....as everyone reading is still waiting for Brent to answer the questions on his claims...which he asks others...as well as showing the Class approved cert he claims one of his boats has to support his claim.

 

Thanks and apologies.

Boats getting crushed by water pressure is fairly relevant. Just not my boats

(because It will be well engineered and will be investigated heavily by people smarter and more experienced than I before hammer goes to nail)

 

I like your description of Herbulot, sadly after heaving read this thread I found few posters who fit that description and you are not among them.

There you lost me, what does Asian cooking as to do with boat building?

What that got to do? Any man cannot produce more than one day’s work in a days, I have been in large shipyard some of the workers there do not pull much weight. Given skill shortage, profit before quality no wonder we have Gulf of Mexico type disaster. The experience of welding for 20 years around 30 boats is a pretty good reference and can command a good renumeration.

 

Well this has nothing to do with asian cooking does it

So rather than being rude you could tell us What was the name of that ship that you were on ? Where did it occur and what class was it under for construction and survey. Then maybe you can be shown why your statement is illogical.

Then perhaps you'd like to comment on the issues we have been discussing here with Brent (who'm you appear to be a supporting act so recently joined and in the fray attacking his adversaries on other threads as well).

Brent is wrong on the curvature, on the compression , on the loads, on the scaling of boats, on the modes of failure, on the use of tensile strength arguments and shows a concerning ignorance about welding, fatigue and framing detail that leads to failure. How do you see those issues when you consider Brent markets here with vigor by attacking proper methods of design and building? If he kept his mouth shut he's be left alone. He's only attacked because he's so rude and so wrong with it.