Realistic scantilings

[waikikin]

Wynand N,
It seems we share some history in that back in 1986(I think) a Van De Stadt 34 was my first yacht build & steel work after finihing my apprenticeship on mostly timber work boats, at age 20, & it was exactly as you describe(in a paddock between the rain showers), after cutting the plates(in my case with a "Nuplex" brand portable plate nibbler), my dad & I plated her up in a day & all the naysayers & observational "advisers" where amazed at the "instant" boat(hull skin!). Still a very pretty chine hull & a great sized boat for most peoples purposes. All the best regards from Jeff.

[DanishBagger]

Originally Posted by Wynand N

Correction, 170 degrees plus....

Oops, yes. My bad.
– a vanishing stability of 170 degree plus!

[Milan]

Wynand, thanks for the photos of the VDS 34 and answers, nicely built boat.

As of angle of vanishing stability, Wynand, Danish Bagger, most of modern sailing boats have angles somewhere between 110 - 130 degrees, but for older generation of boats, say, pre - IOR days, angles of 150 - 160 degrees were common. Hull lines of Brent's boats are form these kind of boats. Also, his boats have a small steering house. In the case of capsize, being from steel and having small windows, there is a good chance that it could stay watertight. If that is the case, air bubble in the steering house would add considerable righting force. So, that number of 170 degrees could actually be accurate.

If you are interested in angles of vanishing stability, Marchaj wrote very informative book "Seaworthiness: The Forgotten Factor".

[DanishBagger]

My point is, that with Brents track record it seems quite unrealistic and quite the inflated number. There are numerous other claims he made in that post back there that seems equally optimistic.
I am not saying one couldn't design a boat like that, but then again, even I can make such unfounded claims, and I'm far from being a NA.
And until I see some curves and analysis from Brent I will stick to my reasoning. "I don't have a scanner, otherwise I would happily post my calculations and stability curves" just doesn't cut it as backing up these claims.

Besides, there's a huge difference - more than one would think offhand, as far as I can gather - between an angle of vanishing stability of, say, 155 degrees and one of 170+.

[Brent Swain]

I make no claim that my methods are anything new in sheet metal working. Cutting out shapes and joining the edges together is the way sheet material has been worked for as long as sheet material has been around.
When it came to metal boats, they ignored centuries of experience in working with sheet material, and simply copied wooden boatbuilding . Van de Stadt was the first to actually take advantage of the versatility of sheet metal . It was a huge improvement , but here is no need to stop there, any more than it was neccesary to stop auto development at the model T Ford..
Lay out the outlines of your deck, on the ground, then cut your sheets out to fit the shape. Then weld all your stringers and beams to the panels, eliminating the overhead welding. Then put the deck panels in the hull starting from the bow. I used to get distortion until I went to 1 inch by 3/8th flatbar for these and minimised the size of the welds( 1/8th inch 6011.) Now the decks remain fair.If you get distortion in the longitudinals it can be bent out, but that's a big job. Easier to keep it out first place.
I leave the welding to the owner. They either hire a student, or do it themselves.
I don' t have access to a scanner . What part of "Don't have" do you not understand? Habla Espanol? No, I don't force my clients to pay me enough to buy all those expensive toys. Too busy field testing my boat.I use library computers which don't have cameras or scanners. If there is a virus or other problem, it's their problem.
Instead of working full time , I work a month a year and cruise the rest of the time , which is what this cruising life is supposed to be about.
Get your advice form somerone who has actually acomplished what you are hoping to accomplish. If that is getting yourself off the treadmill and out cruising, then find someone who has done it.
Adding a wheelhouse makes a huge difference in the angle of vanishing stability. The bouyancy in my 10 inch high wheelhouse has the same effect on ultimate stability as adding 3,000 lbs to the keel of my 31 footer.
Wheelhouses used to be considered a weak point , until we began building more of our cruisers out of steel. Now they are infinitly stronger than the wooden and fibreglas ones that were considered weak.
I remember when building my first boat in the late 60's I hitched a ride with an old guy who talked about commercial fishing from 100 footers . When I said there are all kinds of people cruising the Pacific in boats under 50 feet, he said "Stories! They are all lies! It's impossible to cruise offshore in anything under 100 feet."
Sounds similar to coments made here about my boats.
Brent

[DanishBagger]

Originally Posted by Brent Swain

I don' t have access to a scanner . What part of "Don't have" do you not understand? Habla Espanol? No, I don't force my clients to pay me enough to buy all those expensive toys.

Poor lad. It's such an expensive toy a scanner. Hell you even get them thrown at you when you buy a printer. Hell, most printers these days have an inbuilt scanner/copyer
But if that's too expensive, a cheap ass camera or a cheapo cell phone would fix that problem right away.

Or wait, supposing you actually didn't calculate and drew the angle of vansihing stability by hand, how about this novel idea: Take a screen shot of your calculations and that diagram.
It's really not that hard, and because of this I don't buy your "I don't have access to a scanner" as a good enough reason to not post something that could back up your claims.

Instead of working full time , I work a month a year and cruise the rest of the time , which is what this cruising life is supposed to be about.

Ah, yes, so because you only work part time, you have no need to even slightly validate your claims. Don't be ridiculous. You're here almost every day – if you wanted to, I'm pretty sure you could make it happen, had you actually had those calculations amongst others.

Get your advice form somerone who has actually acomplished what you are hoping to accomplish.

I know what you're _trying_ to say there, but I agree with what you're actually saying, hence I don't take advice from someone like you.

[Echo6]

The Fall 1996 issue of the Metal Boat Quarterly, back issues can bought from the Metal Boat Society, Gary Noble Curtis submitted an article about a 48ft 35,000lb displacement origami hull that he designed to the (no longer published) ABS Rule for Offshore Racing Yachts under 200 feet. He worked up a spread sheet that calculated the proper numbers based on the ABS rules. The boat is primarily longitudinaly framed like most origami hulls, but there are several "...bulkheads or interior joinery of adequate strength, using proper fastening to the longitudinals." These break the span of the longitudinals to about 78". He used a 2 dart pattern, and from the drawings it looks like a nice boat. Judging by his bio, Gary looks like he knows his business. On the matter of getting a boat approved by a standards body such as ABS, I have no idea.

I'll post later on what info I have found on origami hull forms. I don't think the shape limitations are quite as bad as some people think...

[Brent Swain]

Peter Wily
You could build a Saugeen witch, then raft it up to one my 36 footers and compare notes. The Saugeen Witch feels more cramped inside than my 26 footer and doesn't sail anywhere near as well. The deck edge catches you right in the back of the head, just above the shoulders.Or you could talk to Mark and Jean , who sold their Saugeen Witch to build one of my 36 footers , "Costa Vida ", and sailed it around the Pacific recently from BC to Mexico, Pitcairn, Cook Islands,Tonga , Marshall Islands , then back to Northern BC where they work in a resort in Shearwater BC. They are very glad they switched from the Colvin to one of my 36 footers. Talk to them and save yourself a lot of trouble.They were not the first to sell a saugeen witch to build one of my boats. There was no such thing as ultimate stability curves before 1980 and certainly not at the time when the saugeen witch was designed, altho with her moderate beam and high coachroof camber, I don't think it will have any problem whatever righting itself from 180 degrees.
I only design and build what I believe in. Thus I feel the four designs I have will fill any low income cruiser's needs, and don't feel the need to design a lot of boats for the sake of having a lot of designs. Take it or leave it. I couldn't care less. I'm goin cruisin.
The 40 footer is simply a blow up from the 36. The rest of my designs were individually designed from scratch, the 31 based on my last steel boat with huge improvements in balance ,and converted to origami construction.
The 31 and 36 are the product of many boats cruising for decades and the input from their owners have evolved their design over many years, and tens of thousands of miles.
Someone reffered to my book as a "Pamphlet." I feel I have the right to correct that statement here.
My book is roughly 120 pages, over 150 pages for the Spanish version. People tell me that they haven't seen anything in it that has been published elsewhere. It not only gives all the info you need to build origami boats, but includes how to build a 540 gallon a day watermaker for under$1,000 a unit that costs over $10,000 from other sources. It tells you how to build blocks that are far superior to most commercially built ones, in about 20 minutes for under $2, 1/20ththe cost of new ones and far more reliable. It tells you how to build hatches for under $20 that are far superior to anything Bomar makes. It tells you how to build an engine driven 100 amp DC welder for under $30.It tells you how to build a roller furler in a few hours for under $200 , which is far superior to many units that cost thousands of dollars.It tells you how to build a lavac type vacuum head for under $30. It tells you how to build a stainless anchor winch for under $30 .It tells you how to build wind generators and towing generators. it tells you how to design a well balanced hull that will self steer on a broad reach.It tells you how to build a windvane self steering rig for under $30 that has proven far more reliable and better at light air steering than commercially built ones that cost thousandsof dollars. It tells you how to build the simplest possible inside steering arrangement, that lets a five year old steer the boat in a big sea on a broad reach.
Try find all that information in a pamphlet..
Before designing the Yago, Gerd bought my book ,and said that building a couple of blocks saved him the $20 price of the book.
I tired to put info in the book that is usefull to anyone building any type of boat out of any material. Anyone buying the book will save thousands of dollars.
He said that there is nothing much more to say about origami boatbuilding than is in my book, as the process is that simple.
It's been implied here that in a debate amoung very opinionated people who have never read my book nor seen the video nor ever been involved in the construction of an origami boat , and thus haven't a clue about what they are dealing with, that for me to invite people who have, to join the debate, is dirty pool on my part. Where's the logic? ( Hillbilly logic?)
It is repeatedly been implied that a method of contruction that I've used successfully for nearly 30 years and for many dozens of boats, which have been tested at sea far more than most steel boats out there, and been proven beyond any reasonable doubt, wont work. Sounds like some have been living in a kindergarten fantasy land . Grow up and face reality.
It's been suggested that the only way to get a fair deck is to do what can easlily be done at waist level on a workbench should only be done overhead in the most awkward postion imaginable. Where's the logic?
Framed boats that go together quickly are extremely rare, the rare exeption rather than the rule. Origamiboats that take more than three weeks to get the shell together are extremely rare, being the rare exception rather than the rule. Some manage to get framed shells together quickly, but it is extremely rare.
When Joseph started to build a Van De Stadt 33 for his son , after having buil this Roberts design steel 40 footer and sailed it around the Pacific , making him by no means a beginner, he took longer to get just the hull together than I took to build and fully detail a 36.
Brent

[Arvy]

Hi all,

I never expected these kind of reactions on my post. All I wanted to know wether or not my calculated scantlings were somehow realistic. So let me just add to the thread as well as I am the starter of it.

Like Mike (Johns, not Grahams) and kmorin and some others already stated that this was all I asked and that I asked if origami boats could ever pass any class rules. Reading almost all of the posts (took me a few days between work and stuff) at least made clear to me that Origami is not the way to go for me as I do want to build a round bilge which is definately not possible with origami. Of course I don't want to enter in the discussion about brents way of building and posting.

I saw a lot of people speak about vd stadt designs stating that they made a change in design from old fashioned design ways (like wooden boats) to much more modern designs for metal boats. In my past I have done construction detailing and made cnc cutting files for precuts for almost all of the van der stadt designs. I also did the same kind of work for koopmans, vitters, lensen and jongert designs. But I can't remember that there were a lot of changes between those designs considering the way they are constructed. Even tho I did a lot of work on those designs (about 100 in approximatly 4 years) in those days I never did any designwork myself (this is the reason for my questions, and I am talking about 12 years ago).

I believe it was Wynand Nortje who said he doesn't like the precuts and I am wondering why. Like stated before I made a lot of precut files (not the sheets themselves but the cnc cutting files) and can remember only 1 complaint about those (they were always being triple checked amongst the engineer prior to release). The complaint however had nothing to do with the shape but was a construction error by the builder (a home builder). Having no complaints of course doesn't mean all packets were errorless. Most precuts went to professional builders however. I must say I have good experience with them and will create a precut for my own yacht (and will let you know how I feel about actually using precuts myself, might be biased haha).

Funny thing about the treads is that I now tend to use the mc donalds theory and Absence of evidence doesn't mean evidence of absence in my day job.

Grtz,
Arvy

[DanishBagger]

Originally Posted by Arvy

Funny thing about the treads is that I now tend to use the mc donalds theory and Absence of evidence doesn't mean evidence of absence in my day job.

Grtz,
Arvy

Ha ha!


Anyway, It's good to hear you made up your mind, one way or the other.

[Brent Swain]

I was simply suggesting an alternative when someone jumped on me , forcing me to respond.
Had I not responded , his foolish comments would have gone unchallenged.
Brent

[lazeyjack]

Swain I admire your tenacity, where are some of these orgaramy things you are on about?

[DanishBagger]

Originally Posted by Brent Swain

I was simply suggesting an alternative when someone jumped on me , forcing me to respond.
Had I not responded , his foolish comments would have gone unchallenged.
Brent

Ah, yes poor lad. Had it not been for you, the foolish comments wouldn't have company

Puhlease!

[lazeyjack]

Originally Posted by DanishBagger

Ah, yes poor lad. Had it not been for you, the foolish comments wouldn't have company

Puhlease!

there ya go again making something from nothing, some glues are tenacious, does,nt mean I would use the glue, hell you MUST be bored, I dont bleeve you have a proper job Bags, you been here 24 x7, do you have small mans syndrome,? that you continually have to resort to that lowest form of wit, sarcasm
your snide sniping wears even me to a frazzle, praps go tell it to one of your reindeer?

[DanishBagger]

Originally Posted by lazeyjack

there ya go again making something from nothing, some glues are tenacious, does,nt mean I would use the glue, hell you MUST be bored, I dont bleeve you have a proper job Bags, you been here 24 x7, do you have small mans syndrome,?

Actually, I haven't been here 24/7. But from the remark from you the instant I came back here, it looks like you're the one who can't stay away.
Can't you count? I certainly have to ascribe your outburst to something most people call "projection".
It seems you have trouble differentiating between the different threads. Please pull ourself together.

that you continually have to resort to that lowest form of wit,

Ah, yes, it's the lowest form of wit to demand (most of the time) that people use ACTUAL valid arguments, and not state unfounded calims and ad hominems ad nauseum

sarcasm
your snide sniping wears even me to a frazzle, praps go tell it to one of your reindeer?

Well, it doesn't take much to wear you to a "frazzle", does it? Perhaps you ought to get a hobby, then.