Transverse frame calculation

[Ad Hoc]

Originally Posted by mala

The experience of welding for 20 years around 30 boats is a pretty good reference and can command a good renumeration.

Well, ok, lets look at that.

Brent says his boats are easy and quick to make. He says it takes him 90 hours.

Originally Posted by Brent Swain

1
Man hours to put a 36 hull decks ,cabin, cockpit , wheelhouse keel rudder and skeg together is around 90 hours.

So what does he do after that..??

Originally Posted by Brent Swain

After a swim and a lie on the beach. I'll probably head back to the boat for supper , venison steak washed down with some local thimble berry tea ,picked fresh. I've been living like this 11 months a year, since my mid 20's.

So, he welds just for 90hours per year.

Let’s put that into perspective. A fully qualified Class cert approved welder would weld around 45hours per week. So, after 2 weeks the qualified welder does the same as Brent in one year.

So 20 years of 90 hours per year = 1800hours or just 40days of work for a qualified welder, that you call a ‘..pretty good reference..’

So, you think a person who welds just 90 hours per year, is

1) Fully qualified
2) Has lots of experience
3) Can command a high price

I see why you think Brent makes sense now. Your logic is just as baseless as his.

[MikeJohns]

Originally Posted by Brent Swain

..........

Transverse frames have little effect in resisting twisting torsion , or bending from bow to stern. That is done by hull and deck plating resisting being stretched diagnonally .................
Some have spoken about what head of water a hull surface will take. In many Pacific crossings I've never had more than three feet of head against my hull. The hull's buoyancy stops it from geting any higher. She pops up like a cork.That is not the case in much larger hulls which cross several waves at a time , and thus can't rise. Thus such calculations for huge ships are irrelevant for smaller craft.

Here's a simple illustration. Get a thin walled tube grip it at either end and subject it to torsion, what do you see? You get distortion or large wrinkles forming at an angle longitudinally, Now think about how bulkheading/trans framing the tube would stop those wrinkles forming. Nothing stretches at all and you are wrong to use tensile strength figures. It's all buckling.

Transverse frames make a big difference in hull stiffness and strength, by maintaining overall shape.Wracking introduces distortion and the frames keep the shape from changing. That's why the proposed larger hulls based on your method ( frameless, not the darted hull) will be floppy unless framed and also in danger of collapse from pressure head from direct panel loading.

Beware
There is a danger using your statistics from your experience. Class societies have a better database than you. Just because you haven't encountered a particular scenario doesn't mean it won't happen. You should be able to see the danger in that line of argument.

[Brent Swain]

Weld some transverse flat bars accoss a long strip of plate , then twist it. Does having pieces of flat bar across a plate make it harder to twist. No.
Transverse frames could help maintain the shape in much larger ships, with flat topsides, far less so with sailing hull shapes, as with sailing hull shapes the curves do the same job as transverse frames, but how much larger is the debate.
Just because the sky hasn't fallen, doesn't mean it can't happen?
I have always encouraged clients to hire a welder, or welding student, or do it themselves, so I can go back out cruising. I'm hired to get the shell together in under 90 hours, which no one else has managed to do. Would someone who takes 1,000 hours to do the same job be qualified for my hourly wages? Would someone with little or no cruising experience be qualified to make detail decisions, at my hourly wage? No!

[Brent Swain]

t.

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 [/quote]

I think the boat you are referring to was a 40 footer which was going thru Georgeson pass at 15 knots over ground ,when one of her twin keels hit a rock . The trailing edge of the keel was driven up into the hull, due to her not being built to the plans, resulting in a hole there. The skipper was knocked unconscious , and woke up with a lot of water in her. When the coastguard suggested he abandon her, he said' The guy who sold me this boat told me you never abandon a boat until you are able to step up into the lifeboat. He got her home, and repaired, and says if she had been any other design he's seen, she would have been lost.

I suggest you take one of your ten gauge 31 footers with 3,000 lbs of framing and drive her into a wall at 7 knots and see if you don't get buckling. You'll get a lot more than my 3/16th plate hull.
When the 36 footer hit the steel barge, the barge was tied to a dock in front of Gramma's pub in Gibsons.It was about 15 feet wide by about 35 feet long . A 35 foot fishboat was tied to it.There were no fenders of any kind. The 36 T-boned her at 90 degrees. The only damage was a scrape 1/16th of an inch deep, about an inch long, on the stem. The pub was full of witnesses, several who confirmed the story to me.

Mates,

would it be stressing your intelligence to ask for using the "quote" button in the way it was thought to be used?

Thanks
Richard

[Ad Hoc]

Originally Posted by Brent Swain

I'm hired to get the shell together in under 90 hours…

I’m not surprised when you charge $100/ph, you want to be hired.

Originally Posted by Brent Swain

I'm hired to get the shell together in under 90 hours, which no one else has managed to do.

Ahh…so your so called very quick method of pulling and building a complete boat in 90 hours, has been done by…er…just you. Wow, not much of a good advert. If the whole point of this being quick and cheap….surely any Tom Dick or Harry should be able to emulate you, because you say so, you keep saying it is sooooooooooo easy. But the truth is, no one can build your boats in 90 hours.

I can design a midship section of a boat in 5~10mins….does that mean if I show others how to do this, they can too??

Originally Posted by Brent Swain

Would someone with little or no cruising experience be qualified to make detail decisions, at my hourly wage?

I thought it is all in your book???....

Originally Posted by Brent Swain

…My book tells you how to make one.

…My book shows you how.

So, again, your raison d’être is to con suckers into buying your book, see, look how easy it is, anyone can do it.

But you then tell them, well mate 90hours for me, but you’ll take longer, and I wont show you how unless you employ me to build it for you. The total cost for me and raw material steel costs $17,000. The steel is $8000, which leaves $9000 for the labour. Which is $9000/90hours = $100/ph for the work. Nice

Originally Posted by Brent Swain

Steel costs
The steel for a 36 shell is around $8,000 ….One 36 I did and detailed cost around $17,000 for almost all the steel work.

Nice little scam you have. Seduce them with nice sounding anecdotes, which are just that anecdotes, not one single fact. Then whilst they are still intoxicated by your snake oil spin, surreptitiously slip in the bill for your costs…..as “it’s a good time to bury bad news”, so they don’t notice the scam.

You just throw words, lots and lots of words, but no facts, not one single proven verifiable independent fact to support you claims. Just anecdote after anecdote….which as I said before, my dog is bigger than yours!

[Landlubber]

"40 footer which was going thru Georgeson pass at 15 knots over ground "

15 knots...really mate, that IS streeeeeettttttcccchhhhing it a bit.....what was the engine hp to do this speed...hull speed is about 8 knots, 15 is very unbelievable.....

[Ad Hoc]

Originally Posted by Landlubber

"40 footer which was going thru Georgeson pass at 15 knots over ground "

15 knots...really mate, that IS streeeeeettttttcccchhhhing it a bit.....what was the engine hp to do this speed...hull speed is about 8 knots, 15 is very unbelievable.....

Exactly...that is a Froude no around 0.73...way way over the main prismatic hump. That is "planing mode" for a boat of that hull length and speed.

Just more spin and snake oil

[bearflag]

Originally Posted by Landlubber

"40 footer which was going thru Georgeson pass at 15 knots over ground "

15 knots...really mate, that IS streeeeeettttttcccchhhhing it a bit.....what was the engine hp to do this speed...hull speed is about 8 knots, 15 is very unbelievable.....

The hull curvature is aligned with the space-time curvature allowing it to utilize higher dimensional something or anothers....

[Milan]

Originally Posted by Ad Hoc

Exactly...that is a Froude no around 0.73...way way over the main prismatic hump. That is "planing mode" for a boat of that hull length and speed.

Just more spin and snake oil

Maybe tidal current was involved? I heard that it can be very violent on some parts of Canadian coast?

[bearflag]

Originally Posted by Milan

Maybe tidal current was involved? I heard that it can be very violent on some parts of Canadian coast?

He surfed the boat into the barge... I'm sold.

[MikeJohns]

Tides could make it possible and although Brent makes some wild claims regarding structure and beefs up anecdotes for marketing he is an experienced sailor will be aware of hull speed.

But significantly for Brent the welds failed, not the plating tearing at .... PSI.

The barge incident is 2nd hand anecdote and is used to imply great strength. The harbor wall T boned would always be an expensive repair in any vessel framed or not.

It's obvious that the barge incident is no honest indication of how a vessel would fair with something really immovable at hull speed, so there has to be a mitigating factor that reduced the impact. Either it was going a lot slower than the tale allows, or it hit with extreme luck in the center of a large flexible panel. Either way these tales are collected and used to imply that the structural arguments used are valid. But it doesn't relate at all to either the structural issues raised here which Brent needs to address, for example curvature replacing transverse frames.

[MikeJohns]

Originally Posted by Brent Swain

Weld some transverse flat bars accoss a long strip of plate , then twist it. Does having pieces of flat bar across a plate make it harder to twist. No...............!

Now you are misunderstanding the effect shape and restriant has on failure modes (aka buckling) the tube is a simple close analogy to your boat hull, what does a flat plate have to do with it !

Surely you can see that by stopping the sides buckling you add to global strength and rigidity ?

[Milan]

Originally Posted by MikeJohns

Tides could make it possible … he is an experienced sailor will be aware of hull speed ...

Yes, that’s exactly what I was thinking.

Originally Posted by bearflag

He surfed the boat into the barge... I'm sold.

In some parts of BC tidal current can reach up to 20 knots on occasions.

http://www.youtube.com/watch?v=hOpzb9p9SBs
http://www.youtube.com/watch?v=Z-ScxR8aV4Y

And yes, some people do surf tidal bore

http://www.youtube.com/watch?v=4ZuZiLuHM1A
http://www.youtube.com/watch?v=9d6pL3YSGTI

[Ad Hoc]

Originally Posted by Milan

Yes, that’s exactly what I was thinking.

Ahh, yes, good point!..could be just such a case.

But with so much 2nd, 3rd and 4th hand information that comes from Brent and no actual recorded incident reports, it is hard to separate the facts from the fiction.

However, it certainly doesn't address any of the structural issues raised, regradless whether the boat was surfing or not. One is a hydrodynamic issue, the other is structural.